DynamoDB-Beispiele für die Verwendung von Java SDK 2.x

Die folgenden Codebeispiele zeigen Ihnen, wie Sie AWS SDK for Java 2.x mit DynamoDB Aktionen ausführen und allgemeine Szenarien implementieren.

Aktionen sind Codeauszüge aus größeren Programmen und müssen im Kontext ausgeführt werden. Während Aktionen Ihnen zeigen, wie Sie einzelne Servicefunktionen aufrufen, können Sie Aktionen im Kontext der zugehörigen Szenarien und serviceübergreifenden Beispiele sehen.

Szenarien sind Codebeispiele, die Ihnen zeigen, wie Sie eine bestimmte Aufgabe ausführen können, indem Sie mehrere Funktionen innerhalb desselben Services aufrufen.

Jedes Beispiel enthält einen Link zu GitHub, wo Sie Anweisungen zum Einrichten und Ausführen des Codes im Kontext finden.

Erste Schritte

Hallo DynamoDB

Die folgenden Codebeispiele veranschaulichen die ersten Schritte mit DynamoDB.

SDKfür Java 2.x

Anmerkung

Es gibt noch mehr dazu. GitHub Sie sehen das vollständige Beispiel und erfahren, wie Sie das AWS -Code-Beispiel-Repository einrichten und ausführen.

import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.dynamodb.DynamoDbClient;
import software.amazon.awssdk.services.dynamodb.model.DynamoDbException;
import software.amazon.awssdk.services.dynamodb.model.ListTablesRequest;
import software.amazon.awssdk.services.dynamodb.model.ListTablesResponse;
import java.util.List;

/**
 * Before running this Java V2 code example, set up your development
 * environment, including your credentials.
 *
 * For more information, see the following documentation topic:
 *
 * https://docs.aws.amazon.com/sdk-for-java/latest/developer-guide/get-started.html
 */
public class ListTables {
    public static void main(String[] args) {
        System.out.println("Listing your Amazon DynamoDB tables:\n");
        Region region = Region.US_EAST_1;
        DynamoDbClient ddb = DynamoDbClient.builder()
                .region(region)
                .build();
        listAllTables(ddb);
        ddb.close();
    }

    public static void listAllTables(DynamoDbClient ddb) {
        boolean moreTables = true;
        String lastName = null;

        while (moreTables) {
            try {
                ListTablesResponse response = null;
                if (lastName == null) {
                    ListTablesRequest request = ListTablesRequest.builder().build();
                    response = ddb.listTables(request);
                } else {
                    ListTablesRequest request = ListTablesRequest.builder()
                            .exclusiveStartTableName(lastName).build();
                    response = ddb.listTables(request);
                }

                List<String> tableNames = response.tableNames();
                if (tableNames.size() > 0) {
                    for (String curName : tableNames) {
                        System.out.format("* %s\n", curName);
                    }
                } else {
                    System.out.println("No tables found!");
                    System.exit(0);
                }

                lastName = response.lastEvaluatedTableName();
                if (lastName == null) {
                    moreTables = false;
                }

            } catch (DynamoDbException e) {
                System.err.println(e.getMessage());
                System.exit(1);
            }
        }
        System.out.println("\nDone!");
    }
}

• APIEinzelheiten finden Sie ListTablesunter AWS SDK for Java 2.x APIReferenz.

Aktionen

BatchGetItem

Das folgende Codebeispiel zeigt die VerwendungBatchGetItem.

SDKfür Java 2.x

Anmerkung

Es gibt noch mehr dazu. GitHub Sie sehen das vollständige Beispiel und erfahren, wie Sie das AWS -Code-Beispiel-Repository einrichten und ausführen.

zeigt, wie man Batch-Artikel mit dem Service Client abruft.

import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.dynamodb.DynamoDbClient;
import software.amazon.awssdk.services.dynamodb.model.AttributeValue;
import software.amazon.awssdk.services.dynamodb.model.BatchGetItemRequest;
import software.amazon.awssdk.services.dynamodb.model.BatchGetItemResponse;
import software.amazon.awssdk.services.dynamodb.model.KeysAndAttributes;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

/**
 * Before running this Java V2 code example, set up your development environment, including your credentials.
 *
 * For more information, see the following documentation topic:
 *
 * https://docs.aws.amazon.com/sdk-for-java/latest/developer-guide/get-started.html
 */
public class BatchReadItems {
    public static void main(String[] args){
        final String usage = """

                Usage:
                    <tableName> 

                Where:
                    tableName - The Amazon DynamoDB table (for example, Music).\s
                """;

        String tableName = "Music";
        Region region = Region.US_EAST_1;
        DynamoDbClient dynamoDbClient = DynamoDbClient.builder()
            .region(region)
            .build();

        getBatchItems(dynamoDbClient, tableName);
    }

    public static void getBatchItems(DynamoDbClient dynamoDbClient, String tableName) {
        // Define the primary key values for the items you want to retrieve.
        Map<String, AttributeValue> key1 = new HashMap<>();
        key1.put("Artist", AttributeValue.builder().s("Artist1").build());

        Map<String, AttributeValue> key2 = new HashMap<>();
        key2.put("Artist", AttributeValue.builder().s("Artist2").build());

        // Construct the batchGetItem request.
        Map<String, KeysAndAttributes> requestItems = new HashMap<>();
        requestItems.put(tableName, KeysAndAttributes.builder()
            .keys(List.of(key1, key2))
            .projectionExpression("Artist, SongTitle")
            .build());

        BatchGetItemRequest batchGetItemRequest = BatchGetItemRequest.builder()
            .requestItems(requestItems)
            .build();

        // Make the batchGetItem request.
        BatchGetItemResponse batchGetItemResponse = dynamoDbClient.batchGetItem(batchGetItemRequest);

        // Extract and print the retrieved items.
        Map<String, List<Map<String, AttributeValue>>> responses = batchGetItemResponse.responses();
        if (responses.containsKey(tableName)) {
            List<Map<String, AttributeValue>> musicItems = responses.get(tableName);
            for (Map<String, AttributeValue> item : musicItems) {
                System.out.println("Artist: " + item.get("Artist").s() +
                    ", SongTitle: " + item.get("SongTitle").s());
            }
        } else {
            System.out.println("No items retrieved.");
        }
    }
}

zeigt, wie man Batch-Elemente mithilfe des Service-Clients und eines Paginators abruft.

import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.dynamodb.DynamoDbClient;
import software.amazon.awssdk.services.dynamodb.model.AttributeValue;
import software.amazon.awssdk.services.dynamodb.model.BatchGetItemRequest;
import software.amazon.awssdk.services.dynamodb.model.KeysAndAttributes;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

public class BatchGetItemsPaginator {

    public static void main(String[] args){
        final String usage = """

                Usage:
                    <tableName> 

                Where:
                    tableName - The Amazon DynamoDB table (for example, Music).\s
                """;

        String tableName = "Music";
        Region region = Region.US_EAST_1;
        DynamoDbClient dynamoDbClient = DynamoDbClient.builder()
            .region(region)
            .build();

        getBatchItemsPaginator(dynamoDbClient, tableName) ;
    }

    public static void getBatchItemsPaginator(DynamoDbClient dynamoDbClient, String tableName) {
        // Define the primary key values for the items you want to retrieve.
        Map<String, AttributeValue> key1 = new HashMap<>();
        key1.put("Artist", AttributeValue.builder().s("Artist1").build());

        Map<String, AttributeValue> key2 = new HashMap<>();
        key2.put("Artist", AttributeValue.builder().s("Artist2").build());

        // Construct the batchGetItem request.
        Map<String, KeysAndAttributes> requestItems = new HashMap<>();
        requestItems.put(tableName, KeysAndAttributes.builder()
            .keys(List.of(key1, key2))
            .projectionExpression("Artist, SongTitle")
            .build());

        BatchGetItemRequest batchGetItemRequest = BatchGetItemRequest.builder()
            .requestItems(requestItems)
            .build();

        // Use batchGetItemPaginator for paginated requests.
        dynamoDbClient.batchGetItemPaginator(batchGetItemRequest).stream()
            .flatMap(response -> response.responses().getOrDefault(tableName, Collections.emptyList()).stream())
            .forEach(item -> {
                System.out.println("Artist: " + item.get("Artist").s() +
                    ", SongTitle: " + item.get("SongTitle").s());
            });
    }
}

• APIEinzelheiten finden Sie unter Referenz BatchGetItem.AWS SDK for Java 2.x API

BatchWriteItem

Das folgende Codebeispiel zeigt die VerwendungBatchWriteItem.

SDKfür Java 2.x

Anmerkung

Es gibt noch mehr dazu. GitHub Sie sehen das vollständige Beispiel und erfahren, wie Sie das AWS -Code-Beispiel-Repository einrichten und ausführen.

Fügt mithilfe des Service-Clients viele Elemente in eine Tabelle ein.

import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.dynamodb.DynamoDbClient;
import software.amazon.awssdk.services.dynamodb.model.AttributeValue;
import software.amazon.awssdk.services.dynamodb.model.BatchWriteItemRequest;
import software.amazon.awssdk.services.dynamodb.model.BatchWriteItemResponse;
import software.amazon.awssdk.services.dynamodb.model.DynamoDbException;
import software.amazon.awssdk.services.dynamodb.model.PutRequest;
import software.amazon.awssdk.services.dynamodb.model.WriteRequest;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

/**
 * Before running this Java V2 code example, set up your development environment, including your credentials.
 *
 * For more information, see the following documentation topic:
 *
 * https://docs.aws.amazon.com/sdk-for-java/latest/developer-guide/get-started.html
 */
public class BatchWriteItems {
    public static void main(String[] args){
        final String usage = """

                Usage:
                    <tableName> 

                Where:
                    tableName - The Amazon DynamoDB table (for example, Music).\s
                """;

        String tableName = "Music";
        Region region = Region.US_EAST_1;
        DynamoDbClient dynamoDbClient = DynamoDbClient.builder()
            .region(region)
            .build();

        addBatchItems(dynamoDbClient, tableName);
    }

    public static void addBatchItems(DynamoDbClient dynamoDbClient, String tableName) {
        // Specify the updates you want to perform.
        List<WriteRequest> writeRequests = new ArrayList<>();

        // Set item 1.
        Map<String, AttributeValue> item1Attributes = new HashMap<>();
        item1Attributes.put("Artist", AttributeValue.builder().s("Artist1").build());
        item1Attributes.put("Rating", AttributeValue.builder().s("5").build());
        item1Attributes.put("Comments", AttributeValue.builder().s("Great song!").build());
        item1Attributes.put("SongTitle", AttributeValue.builder().s("SongTitle1").build());
        writeRequests.add(WriteRequest.builder().putRequest(PutRequest.builder().item(item1Attributes).build()).build());

        // Set item 2.
        Map<String, AttributeValue> item2Attributes = new HashMap<>();
        item2Attributes.put("Artist", AttributeValue.builder().s("Artist2").build());
        item2Attributes.put("Rating", AttributeValue.builder().s("4").build());
        item2Attributes.put("Comments", AttributeValue.builder().s("Nice melody.").build());
        item2Attributes.put("SongTitle", AttributeValue.builder().s("SongTitle2").build());
        writeRequests.add(WriteRequest.builder().putRequest(PutRequest.builder().item(item2Attributes).build()).build());

        try {
            // Create the BatchWriteItemRequest.
            BatchWriteItemRequest batchWriteItemRequest = BatchWriteItemRequest.builder()
                .requestItems(Map.of(tableName, writeRequests))
                .build();

            // Execute the BatchWriteItem operation.
            BatchWriteItemResponse batchWriteItemResponse = dynamoDbClient.batchWriteItem(batchWriteItemRequest);

            // Process the response.
            System.out.println("Batch write successful: " + batchWriteItemResponse);

        } catch (DynamoDbException e) {
            System.err.println(e.getMessage());
            System.exit(1);
        }
    }
}

Fügt mithilfe des erweiterten Clients viele Elemente in eine Tabelle ein.

import com.example.dynamodb.Customer;
import com.example.dynamodb.Music;
import software.amazon.awssdk.enhanced.dynamodb.DynamoDbEnhancedClient;
import software.amazon.awssdk.enhanced.dynamodb.DynamoDbTable;
import software.amazon.awssdk.enhanced.dynamodb.Key;
import software.amazon.awssdk.enhanced.dynamodb.TableSchema;
import software.amazon.awssdk.enhanced.dynamodb.model.BatchWriteItemEnhancedRequest;
import software.amazon.awssdk.enhanced.dynamodb.model.WriteBatch;
import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.dynamodb.DynamoDbClient;
import software.amazon.awssdk.services.dynamodb.model.DynamoDbException;
import java.time.Instant;
import java.time.LocalDate;
import java.time.LocalDateTime;
import java.time.ZoneOffset;

/*
 * Before running this code example, create an Amazon DynamoDB table named Customer with these columns:
 *   - id - the id of the record that is the key
 *   - custName - the customer name
 *   - email - the email value
 *   - registrationDate - an instant value when the item was added to the table
 *
 * Also, ensure that you have set up your development environment, including your credentials.
 *
 * For information, see this documentation topic:
 *
 * https://docs.aws.amazon.com/sdk-for-java/latest/developer-guide/get-started.html
 */
public class EnhancedBatchWriteItems {
        public static void main(String[] args) {
                Region region = Region.US_EAST_1;
                DynamoDbClient ddb = DynamoDbClient.builder()
                                .region(region)
                                .build();
                DynamoDbEnhancedClient enhancedClient = DynamoDbEnhancedClient.builder()
                                .dynamoDbClient(ddb)
                                .build();
                putBatchRecords(enhancedClient);
                ddb.close();
        }

        public static void putBatchRecords(DynamoDbEnhancedClient enhancedClient) {
                try {
                        DynamoDbTable<Customer> customerMappedTable = enhancedClient.table("Customer",
                                        TableSchema.fromBean(Customer.class));
                        DynamoDbTable<Music> musicMappedTable = enhancedClient.table("Music",
                                        TableSchema.fromBean(Music.class));
                        LocalDate localDate = LocalDate.parse("2020-04-07");
                        LocalDateTime localDateTime = localDate.atStartOfDay();
                        Instant instant = localDateTime.toInstant(ZoneOffset.UTC);

                        Customer record2 = new Customer();
                        record2.setCustName("Fred Pink");
                        record2.setId("id110");
                        record2.setEmail("[e-mail]");
                        record2.setRegistrationDate(instant);

                        Customer record3 = new Customer();
                        record3.setCustName("Susan Pink");
                        record3.setId("id120");
                        record3.setEmail("[e-mail]");
                        record3.setRegistrationDate(instant);

                        Customer record4 = new Customer();
                        record4.setCustName("Jerry orange");
                        record4.setId("id101");
                        record4.setEmail("[e-mail]");
                        record4.setRegistrationDate(instant);

                        BatchWriteItemEnhancedRequest batchWriteItemEnhancedRequest = BatchWriteItemEnhancedRequest
                                        .builder()
                                        .writeBatches(
                                                        WriteBatch.builder(Customer.class) // add items to the Customer
                                                                                           // table
                                                                        .mappedTableResource(customerMappedTable)
                                                                        .addPutItem(builder -> builder.item(record2))
                                                                        .addPutItem(builder -> builder.item(record3))
                                                                        .addPutItem(builder -> builder.item(record4))
                                                                        .build(),
                                                        WriteBatch.builder(Music.class) // delete an item from the Music
                                                                                        // table
                                                                        .mappedTableResource(musicMappedTable)
                                                                        .addDeleteItem(builder -> builder.key(
                                                                                        Key.builder().partitionValue(
                                                                                                        "Famous Band")
                                                                                                        .build()))
                                                                        .build())
                                        .build();

                        // Add three items to the Customer table and delete one item from the Music
                        // table.
                        enhancedClient.batchWriteItem(batchWriteItemEnhancedRequest);
                        System.out.println("done");

                } catch (DynamoDbException e) {
                        System.err.println(e.getMessage());
                        System.exit(1);
                }
        }
}

• APIEinzelheiten finden Sie BatchWriteItemunter AWS SDK for Java 2.x APIReferenz.

CreateTable

Das folgende Codebeispiel zeigt die VerwendungCreateTable.

SDKfür Java 2.x

Anmerkung

Es gibt noch mehr dazu. GitHub Sie sehen das vollständige Beispiel und erfahren, wie Sie das AWS -Code-Beispiel-Repository einrichten und ausführen.

import software.amazon.awssdk.core.waiters.WaiterResponse;
import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.dynamodb.DynamoDbClient;
import software.amazon.awssdk.services.dynamodb.model.AttributeDefinition;
import software.amazon.awssdk.services.dynamodb.model.CreateTableRequest;
import software.amazon.awssdk.services.dynamodb.model.CreateTableResponse;
import software.amazon.awssdk.services.dynamodb.model.DescribeTableRequest;
import software.amazon.awssdk.services.dynamodb.model.DescribeTableResponse;
import software.amazon.awssdk.services.dynamodb.model.DynamoDbException;
import software.amazon.awssdk.services.dynamodb.model.KeySchemaElement;
import software.amazon.awssdk.services.dynamodb.model.KeyType;
import software.amazon.awssdk.services.dynamodb.model.ProvisionedThroughput;
import software.amazon.awssdk.services.dynamodb.model.ScalarAttributeType;
import software.amazon.awssdk.services.dynamodb.waiters.DynamoDbWaiter;

/**
 * Before running this Java V2 code example, set up your development
 * environment, including your credentials.
 *
 * For more information, see the following documentation topic:
 *
 * https://docs.aws.amazon.com/sdk-for-java/latest/developer-guide/get-started.html
 */
public class CreateTable {
    public static void main(String[] args) {
        final String usage = """

                Usage:
                    <tableName> <key>

                Where:
                    tableName - The Amazon DynamoDB table to create (for example, Music3).
                    key - The key for the Amazon DynamoDB table (for example, Artist).
                """;

        if (args.length != 2) {
            System.out.println(usage);
            System.exit(1);
        }

        String tableName = args[0];
        String key = args[1];
        System.out.println("Creating an Amazon DynamoDB table " + tableName + " with a simple primary key: " + key);
        Region region = Region.US_EAST_1;
        DynamoDbClient ddb = DynamoDbClient.builder()
                .region(region)
                .build();

        String result = createTable(ddb, tableName, key);
        System.out.println("New table is " + result);
        ddb.close();
    }

    public static String createTable(DynamoDbClient ddb, String tableName, String key) {
        DynamoDbWaiter dbWaiter = ddb.waiter();
        CreateTableRequest request = CreateTableRequest.builder()
                .attributeDefinitions(AttributeDefinition.builder()
                        .attributeName(key)
                        .attributeType(ScalarAttributeType.S)
                        .build())
                .keySchema(KeySchemaElement.builder()
                        .attributeName(key)
                        .keyType(KeyType.HASH)
                        .build())
                .provisionedThroughput(ProvisionedThroughput.builder()
                        .readCapacityUnits(10L)
                        .writeCapacityUnits(10L)
                        .build())
                .tableName(tableName)
                .build();

        String newTable;
        try {
            CreateTableResponse response = ddb.createTable(request);
            DescribeTableRequest tableRequest = DescribeTableRequest.builder()
                    .tableName(tableName)
                    .build();

            // Wait until the Amazon DynamoDB table is created.
            WaiterResponse<DescribeTableResponse> waiterResponse = dbWaiter.waitUntilTableExists(tableRequest);
            waiterResponse.matched().response().ifPresent(System.out::println);
            newTable = response.tableDescription().tableName();
            return newTable;

        } catch (DynamoDbException e) {
            System.err.println(e.getMessage());
            System.exit(1);
        }
        return "";
    }
}

• APIEinzelheiten finden Sie CreateTableunter AWS SDK for Java 2.x APIReferenz.

DeleteItem

Das folgende Codebeispiel zeigt die VerwendungDeleteItem.

SDKfür Java 2.x

Anmerkung

Es gibt noch mehr dazu. GitHub Sie sehen das vollständige Beispiel und erfahren, wie Sie das AWS -Code-Beispiel-Repository einrichten und ausführen.

import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.dynamodb.DynamoDbClient;
import software.amazon.awssdk.services.dynamodb.model.AttributeValue;
import software.amazon.awssdk.services.dynamodb.model.DeleteItemRequest;
import software.amazon.awssdk.services.dynamodb.model.DynamoDbException;
import java.util.HashMap;

/**
 * Before running this Java V2 code example, set up your development
 * environment, including your credentials.
 *
 * For more information, see the following documentation topic:
 *
 * https://docs.aws.amazon.com/sdk-for-java/latest/developer-guide/get-started.html
 */
public class DeleteItem {
    public static void main(String[] args) {
        final String usage = """

                Usage:
                    <tableName> <key> <keyval>

                Where:
                    tableName - The Amazon DynamoDB table to delete the item from (for example, Music3).
                    key - The key used in the Amazon DynamoDB table (for example, Artist).\s
                    keyval - The key value that represents the item to delete (for example, Famous Band).
                """;

        if (args.length != 3) {
            System.out.println(usage);
            System.exit(1);
        }

        String tableName = args[0];
        String key = args[1];
        String keyVal = args[2];
        System.out.format("Deleting item \"%s\" from %s\n", keyVal, tableName);
        Region region = Region.US_EAST_1;
        DynamoDbClient ddb = DynamoDbClient.builder()
                .region(region)
                .build();

        deleteDynamoDBItem(ddb, tableName, key, keyVal);
        ddb.close();
    }

    public static void deleteDynamoDBItem(DynamoDbClient ddb, String tableName, String key, String keyVal) {
        HashMap<String, AttributeValue> keyToGet = new HashMap<>();
        keyToGet.put(key, AttributeValue.builder()
                .s(keyVal)
                .build());

        DeleteItemRequest deleteReq = DeleteItemRequest.builder()
                .tableName(tableName)
                .key(keyToGet)
                .build();

        try {
            ddb.deleteItem(deleteReq);
        } catch (DynamoDbException e) {
            System.err.println(e.getMessage());
            System.exit(1);
        }
    }
}

• APIEinzelheiten finden Sie DeleteItemunter AWS SDK for Java 2.x APIReferenz.

DeleteTable

Das folgende Codebeispiel zeigt die VerwendungDeleteTable.

SDKfür Java 2.x

Anmerkung

Es gibt noch mehr dazu. GitHub Sie sehen das vollständige Beispiel und erfahren, wie Sie das AWS -Code-Beispiel-Repository einrichten und ausführen.

import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.dynamodb.model.DynamoDbException;
import software.amazon.awssdk.services.dynamodb.DynamoDbClient;
import software.amazon.awssdk.services.dynamodb.model.DeleteTableRequest;

/**
 * Before running this Java V2 code example, set up your development
 * environment, including your credentials.
 *
 * For more information, see the following documentation topic:
 *
 * https://docs.aws.amazon.com/sdk-for-java/latest/developer-guide/get-started.html
 */

public class DeleteTable {
    public static void main(String[] args) {
        final String usage = """

                Usage:
                    <tableName>

                Where:
                    tableName - The Amazon DynamoDB table to delete (for example, Music3).

                **Warning** This program will delete the table that you specify!
                """;

        if (args.length != 1) {
            System.out.println(usage);
            System.exit(1);
        }

        String tableName = args[0];
        System.out.format("Deleting the Amazon DynamoDB table %s...\n", tableName);
        Region region = Region.US_EAST_1;
        DynamoDbClient ddb = DynamoDbClient.builder()
                .region(region)
                .build();

        deleteDynamoDBTable(ddb, tableName);
        ddb.close();
    }

    public static void deleteDynamoDBTable(DynamoDbClient ddb, String tableName) {
        DeleteTableRequest request = DeleteTableRequest.builder()
                .tableName(tableName)
                .build();

        try {
            ddb.deleteTable(request);

        } catch (DynamoDbException e) {
            System.err.println(e.getMessage());
            System.exit(1);
        }
        System.out.println(tableName + " was successfully deleted!");
    }
}

• APIEinzelheiten finden Sie DeleteTableunter AWS SDK for Java 2.x APIReferenz.

DescribeTable

Das folgende Codebeispiel zeigt die VerwendungDescribeTable.

SDKfür Java 2.x

Anmerkung

Es gibt noch mehr dazu. GitHub Sie sehen das vollständige Beispiel und erfahren, wie Sie das AWS -Code-Beispiel-Repository einrichten und ausführen.

import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.dynamodb.model.DynamoDbException;
import software.amazon.awssdk.services.dynamodb.DynamoDbClient;
import software.amazon.awssdk.services.dynamodb.model.AttributeDefinition;
import software.amazon.awssdk.services.dynamodb.model.DescribeTableRequest;
import software.amazon.awssdk.services.dynamodb.model.ProvisionedThroughputDescription;
import software.amazon.awssdk.services.dynamodb.model.TableDescription;
import java.util.List;

/**
 * Before running this Java V2 code example, set up your development
 * environment, including your credentials.
 *
 * For more information, see the following documentation topic:
 *
 * https://docs.aws.amazon.com/sdk-for-java/latest/developer-guide/get-started.html
 */
public class DescribeTable {
    public static void main(String[] args) {
        final String usage = """

                Usage:
                    <tableName>

                Where:
                    tableName - The Amazon DynamoDB table to get information about (for example, Music3).
                """;

        if (args.length != 1) {
            System.out.println(usage);
            System.exit(1);
        }

        String tableName = args[0];
        System.out.format("Getting description for %s\n\n", tableName);
        Region region = Region.US_EAST_1;
        DynamoDbClient ddb = DynamoDbClient.builder()
                .region(region)
                .build();

        describeDymamoDBTable(ddb, tableName);
        ddb.close();
    }

    public static void describeDymamoDBTable(DynamoDbClient ddb, String tableName) {
        DescribeTableRequest request = DescribeTableRequest.builder()
                .tableName(tableName)
                .build();

        try {
            TableDescription tableInfo = ddb.describeTable(request).table();
            if (tableInfo != null) {
                System.out.format("Table name  : %s\n", tableInfo.tableName());
                System.out.format("Table ARN   : %s\n", tableInfo.tableArn());
                System.out.format("Status      : %s\n", tableInfo.tableStatus());
                System.out.format("Item count  : %d\n", tableInfo.itemCount());
                System.out.format("Size (bytes): %d\n", tableInfo.tableSizeBytes());

                ProvisionedThroughputDescription throughputInfo = tableInfo.provisionedThroughput();
                System.out.println("Throughput");
                System.out.format("  Read Capacity : %d\n", throughputInfo.readCapacityUnits());
                System.out.format("  Write Capacity: %d\n", throughputInfo.writeCapacityUnits());

                List<AttributeDefinition> attributes = tableInfo.attributeDefinitions();
                System.out.println("Attributes");
                for (AttributeDefinition a : attributes) {
                    System.out.format("  %s (%s)\n", a.attributeName(), a.attributeType());
                }
            }

        } catch (DynamoDbException e) {
            System.err.println(e.getMessage());
            System.exit(1);
        }
        System.out.println("\nDone!");
    }
}

• APIEinzelheiten finden Sie DescribeTableunter AWS SDK for Java 2.x APIReferenz.

DescribeTimeToLive

Das folgende Codebeispiel zeigt die VerwendungDescribeTimeToLive.

SDKfür Java 2.x

Beschreiben Sie die TTL Konfiguration einer vorhandenen DynamoDB-Tabelle.

import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.dynamodb.DynamoDbClient;
import software.amazon.awssdk.services.dynamodb.model.DescribeTimeToLiveRequest;
import software.amazon.awssdk.services.dynamodb.model.DescribeTimeToLiveResponse;
import software.amazon.awssdk.services.dynamodb.model.DynamoDbException;
import software.amazon.awssdk.services.dynamodb.model.ResourceNotFoundException;

import java.util.Optional;

        final DescribeTimeToLiveRequest request = DescribeTimeToLiveRequest.builder()
                .tableName(tableName)
                .build();
        try (DynamoDbClient ddb = DynamoDbClient.builder()
                .region(region)
                .build()) {
            final DescribeTimeToLiveResponse response = ddb.describeTimeToLive(request);
            System.out.println(tableName + " description of time to live is "
                    + response.toString());
        } catch (ResourceNotFoundException e) {
            System.err.format("Error: The Amazon DynamoDB table \"%s\" can't be found.\n", tableName);
            System.exit(1);
        } catch (DynamoDbException e) {
            System.err.println(e.getMessage());
            System.exit(1);
        }
        System.exit(0);

• APIEinzelheiten finden Sie unter Referenz DescribeTimeToLive.AWS SDK for Java 2.x API

GetItem

Das folgende Codebeispiel zeigt die VerwendungGetItem.

SDKfür Java 2.x

Anmerkung

Es gibt noch mehr dazu. GitHub Sie sehen das vollständige Beispiel und erfahren, wie Sie das AWS -Code-Beispiel-Repository einrichten und ausführen.

Ruft mithilfe von ein Element aus einer Tabelle ab DynamoDbClient.

import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.dynamodb.model.DynamoDbException;
import software.amazon.awssdk.services.dynamodb.DynamoDbClient;
import software.amazon.awssdk.services.dynamodb.model.AttributeValue;
import software.amazon.awssdk.services.dynamodb.model.GetItemRequest;
import java.util.HashMap;
import java.util.Map;
import java.util.Set;

/**
 * Before running this Java V2 code example, set up your development
 * environment, including your credentials.
 *
 * For more information, see the following documentation topic:
 *
 * https://docs.aws.amazon.com/sdk-for-java/latest/developer-guide/get-started.html
 *
 * To get an item from an Amazon DynamoDB table using the AWS SDK for Java V2,
 * its better practice to use the
 * Enhanced Client, see the EnhancedGetItem example.
 */
public class GetItem {
    public static void main(String[] args) {
        final String usage = """

                Usage:
                    <tableName> <key> <keyVal>

                Where:
                    tableName - The Amazon DynamoDB table from which an item is retrieved (for example, Music3).\s
                    key - The key used in the Amazon DynamoDB table (for example, Artist).\s
                    keyval - The key value that represents the item to get (for example, Famous Band).
                """;

        if (args.length != 3) {
            System.out.println(usage);
            System.exit(1);
        }

        String tableName = args[0];
        String key = args[1];
        String keyVal = args[2];
        System.out.format("Retrieving item \"%s\" from \"%s\"\n", keyVal, tableName);
        Region region = Region.US_EAST_1;
        DynamoDbClient ddb = DynamoDbClient.builder()
                .region(region)
                .build();

        getDynamoDBItem(ddb, tableName, key, keyVal);
        ddb.close();
    }

    public static void getDynamoDBItem(DynamoDbClient ddb, String tableName, String key, String keyVal) {
        HashMap<String, AttributeValue> keyToGet = new HashMap<>();
        keyToGet.put(key, AttributeValue.builder()
                .s(keyVal)
                .build());

        GetItemRequest request = GetItemRequest.builder()
                .key(keyToGet)
                .tableName(tableName)
                .build();

        try {
            // If there is no matching item, GetItem does not return any data.
            Map<String, AttributeValue> returnedItem = ddb.getItem(request).item();
            if (returnedItem.isEmpty())
                System.out.format("No item found with the key %s!\n", key);
            else {
                Set<String> keys = returnedItem.keySet();
                System.out.println("Amazon DynamoDB table attributes: \n");
                for (String key1 : keys) {
                    System.out.format("%s: %s\n", key1, returnedItem.get(key1).toString());
                }
            }

        } catch (DynamoDbException e) {
            System.err.println(e.getMessage());
            System.exit(1);
        }
    }
}

• APIEinzelheiten finden Sie GetItemunter AWS SDK for Java 2.x APIReferenz.

ListTables

Das folgende Codebeispiel zeigt die VerwendungListTables.

SDKfür Java 2.x

Anmerkung

Es gibt noch mehr dazu. GitHub Sie sehen das vollständige Beispiel und erfahren, wie Sie das AWS -Code-Beispiel-Repository einrichten und ausführen.

import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.dynamodb.DynamoDbClient;
import software.amazon.awssdk.services.dynamodb.model.DynamoDbException;
import software.amazon.awssdk.services.dynamodb.model.ListTablesRequest;
import software.amazon.awssdk.services.dynamodb.model.ListTablesResponse;
import java.util.List;

/**
 * Before running this Java V2 code example, set up your development
 * environment, including your credentials.
 *
 * For more information, see the following documentation topic:
 *
 * https://docs.aws.amazon.com/sdk-for-java/latest/developer-guide/get-started.html
 */
public class ListTables {
    public static void main(String[] args) {
        System.out.println("Listing your Amazon DynamoDB tables:\n");
        Region region = Region.US_EAST_1;
        DynamoDbClient ddb = DynamoDbClient.builder()
                .region(region)
                .build();
        listAllTables(ddb);
        ddb.close();
    }

    public static void listAllTables(DynamoDbClient ddb) {
        boolean moreTables = true;
        String lastName = null;

        while (moreTables) {
            try {
                ListTablesResponse response = null;
                if (lastName == null) {
                    ListTablesRequest request = ListTablesRequest.builder().build();
                    response = ddb.listTables(request);
                } else {
                    ListTablesRequest request = ListTablesRequest.builder()
                            .exclusiveStartTableName(lastName).build();
                    response = ddb.listTables(request);
                }

                List<String> tableNames = response.tableNames();
                if (tableNames.size() > 0) {
                    for (String curName : tableNames) {
                        System.out.format("* %s\n", curName);
                    }
                } else {
                    System.out.println("No tables found!");
                    System.exit(0);
                }

                lastName = response.lastEvaluatedTableName();
                if (lastName == null) {
                    moreTables = false;
                }

            } catch (DynamoDbException e) {
                System.err.println(e.getMessage());
                System.exit(1);
            }
        }
        System.out.println("\nDone!");
    }
}

• APIEinzelheiten finden Sie ListTablesunter AWS SDK for Java 2.x APIReferenz.

PutItem

Das folgende Codebeispiel zeigt die VerwendungPutItem.

SDKfür Java 2.x

Anmerkung

Es gibt noch mehr dazu. GitHub Sie sehen das vollständige Beispiel und erfahren, wie Sie das AWS -Code-Beispiel-Repository einrichten und ausführen.

Fügt ein Element in eine Tabelle ein mit DynamoDbClient.

import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.dynamodb.DynamoDbClient;
import software.amazon.awssdk.services.dynamodb.model.AttributeValue;
import software.amazon.awssdk.services.dynamodb.model.DynamoDbException;
import software.amazon.awssdk.services.dynamodb.model.PutItemRequest;
import software.amazon.awssdk.services.dynamodb.model.PutItemResponse;
import software.amazon.awssdk.services.dynamodb.model.ResourceNotFoundException;
import java.util.HashMap;

/**
 * Before running this Java V2 code example, set up your development
 * environment, including your credentials.
 *
 * For more information, see the following documentation topic:
 *
 * https://docs.aws.amazon.com/sdk-for-java/latest/developer-guide/get-started.html
 *
 * To place items into an Amazon DynamoDB table using the AWS SDK for Java V2,
 * its better practice to use the
 * Enhanced Client. See the EnhancedPutItem example.
 */
public class PutItem {
    public static void main(String[] args) {
        final String usage = """

                Usage:
                    <tableName> <key> <keyVal> <albumtitle> <albumtitleval> <awards> <awardsval> <Songtitle> <songtitleval>

                Where:
                    tableName - The Amazon DynamoDB table in which an item is placed (for example, Music3).
                    key - The key used in the Amazon DynamoDB table (for example, Artist).
                    keyval - The key value that represents the item to get (for example, Famous Band).
                    albumTitle - The Album title (for example, AlbumTitle).
                    AlbumTitleValue - The name of the album (for example, Songs About Life ).
                    Awards - The awards column (for example, Awards).
                    AwardVal - The value of the awards (for example, 10).
                    SongTitle - The song title (for example, SongTitle).
                    SongTitleVal - The value of the song title (for example, Happy Day).
                **Warning** This program will  place an item that you specify into a table!
                """;

        if (args.length != 9) {
            System.out.println(usage);
            System.exit(1);
        }

        String tableName = args[0];
        String key = args[1];
        String keyVal = args[2];
        String albumTitle = args[3];
        String albumTitleValue = args[4];
        String awards = args[5];
        String awardVal = args[6];
        String songTitle = args[7];
        String songTitleVal = args[8];

        Region region = Region.US_EAST_1;
        DynamoDbClient ddb = DynamoDbClient.builder()
                .region(region)
                .build();

        putItemInTable(ddb, tableName, key, keyVal, albumTitle, albumTitleValue, awards, awardVal, songTitle,
                songTitleVal);
        System.out.println("Done!");
        ddb.close();
    }

    public static void putItemInTable(DynamoDbClient ddb,
            String tableName,
            String key,
            String keyVal,
            String albumTitle,
            String albumTitleValue,
            String awards,
            String awardVal,
            String songTitle,
            String songTitleVal) {

        HashMap<String, AttributeValue> itemValues = new HashMap<>();
        itemValues.put(key, AttributeValue.builder().s(keyVal).build());
        itemValues.put(songTitle, AttributeValue.builder().s(songTitleVal).build());
        itemValues.put(albumTitle, AttributeValue.builder().s(albumTitleValue).build());
        itemValues.put(awards, AttributeValue.builder().s(awardVal).build());

        PutItemRequest request = PutItemRequest.builder()
                .tableName(tableName)
                .item(itemValues)
                .build();

        try {
            PutItemResponse response = ddb.putItem(request);
            System.out.println(tableName + " was successfully updated. The request id is "
                    + response.responseMetadata().requestId());

        } catch (ResourceNotFoundException e) {
            System.err.format("Error: The Amazon DynamoDB table \"%s\" can't be found.\n", tableName);
            System.err.println("Be sure that it exists and that you've typed its name correctly!");
            System.exit(1);
        } catch (DynamoDbException e) {
            System.err.println(e.getMessage());
            System.exit(1);
        }
    }
}

• APIEinzelheiten finden Sie PutItemunter AWS SDK for Java 2.x APIReferenz.

Query

Das folgende Codebeispiel zeigt die VerwendungQuery.

SDKfür Java 2.x

Anmerkung

Es gibt noch mehr dazu. GitHub Sie sehen das vollständige Beispiel und erfahren, wie Sie das AWS -Code-Beispiel-Repository einrichten und ausführen.

Fragt eine Tabelle ab mithilfe von DynamoDbClient.

import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.dynamodb.DynamoDbClient;
import software.amazon.awssdk.services.dynamodb.model.AttributeValue;
import software.amazon.awssdk.services.dynamodb.model.DynamoDbException;
import software.amazon.awssdk.services.dynamodb.model.QueryRequest;
import software.amazon.awssdk.services.dynamodb.model.QueryResponse;
import java.util.HashMap;

/**
 * Before running this Java V2 code example, set up your development
 * environment, including your credentials.
 *
 * For more information, see the following documentation topic:
 *
 * https://docs.aws.amazon.com/sdk-for-java/latest/developer-guide/get-started.html
 *
 * To query items from an Amazon DynamoDB table using the AWS SDK for Java V2,
 * its better practice to use the
 * Enhanced Client. See the EnhancedQueryRecords example.
 */
public class Query {
    public static void main(String[] args) {
        final String usage = """

                Usage:
                    <tableName> <partitionKeyName> <partitionKeyVal>

                Where:
                    tableName - The Amazon DynamoDB table to put the item in (for example, Music3).
                    partitionKeyName - The partition key name of the Amazon DynamoDB table (for example, Artist).
                    partitionKeyVal - The value of the partition key that should match (for example, Famous Band).
                """;

        if (args.length != 3) {
            System.out.println(usage);
            System.exit(1);
        }

        String tableName = args[0];
        String partitionKeyName = args[1];
        String partitionKeyVal = args[2];

        // For more information about an alias, see:
        // https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/Expressions.ExpressionAttributeNames.html
        String partitionAlias = "#a";

        System.out.format("Querying %s", tableName);
        System.out.println("");
        Region region = Region.US_EAST_1;
        DynamoDbClient ddb = DynamoDbClient.builder()
                .region(region)
                .build();

        int count = queryTable(ddb, tableName, partitionKeyName, partitionKeyVal, partitionAlias);
        System.out.println("There were " + count + "  record(s) returned");
        ddb.close();
    }

    public static int queryTable(DynamoDbClient ddb, String tableName, String partitionKeyName, String partitionKeyVal,
            String partitionAlias) {
        // Set up an alias for the partition key name in case it's a reserved word.
        HashMap<String, String> attrNameAlias = new HashMap<String, String>();
        attrNameAlias.put(partitionAlias, partitionKeyName);

        // Set up mapping of the partition name with the value.
        HashMap<String, AttributeValue> attrValues = new HashMap<>();
        attrValues.put(":" + partitionKeyName, AttributeValue.builder()
                .s(partitionKeyVal)
                .build());

        QueryRequest queryReq = QueryRequest.builder()
                .tableName(tableName)
                .keyConditionExpression(partitionAlias + " = :" + partitionKeyName)
                .expressionAttributeNames(attrNameAlias)
                .expressionAttributeValues(attrValues)
                .build();

        try {
            QueryResponse response = ddb.query(queryReq);
            return response.count();

        } catch (DynamoDbException e) {
            System.err.println(e.getMessage());
            System.exit(1);
        }
        return -1;
    }
}

Fragt eine Tabelle mithilfe von DynamoDbClient und eines sekundären Index ab.

import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.dynamodb.DynamoDbClient;
import software.amazon.awssdk.services.dynamodb.model.AttributeValue;
import software.amazon.awssdk.services.dynamodb.model.DynamoDbException;
import software.amazon.awssdk.services.dynamodb.model.QueryRequest;
import software.amazon.awssdk.services.dynamodb.model.QueryResponse;
import java.util.HashMap;
import java.util.Map;

/**
 * Before running this Java V2 code example, set up your development
 * environment, including your credentials.
 *
 * For more information, see the following documentation topic:
 *
 * https://docs.aws.amazon.com/sdk-for-java/latest/developer-guide/get-started.html
 *
 * Create the Movies table by running the Scenario example and loading the Movie
 * data from the JSON file. Next create a secondary
 * index for the Movies table that uses only the year column. Name the index
 * **year-index**. For more information, see:
 *
 * https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/GSI.html
 */
public class QueryItemsUsingIndex {
    public static void main(String[] args) {
        String tableName = "Movies";
        Region region = Region.US_EAST_1;
        DynamoDbClient ddb = DynamoDbClient.builder()
                .region(region)
                .build();

        queryIndex(ddb, tableName);
        ddb.close();
    }

    public static void queryIndex(DynamoDbClient ddb, String tableName) {
        try {
            Map<String, String> expressionAttributesNames = new HashMap<>();
            expressionAttributesNames.put("#year", "year");
            Map<String, AttributeValue> expressionAttributeValues = new HashMap<>();
            expressionAttributeValues.put(":yearValue", AttributeValue.builder().n("2013").build());

            QueryRequest request = QueryRequest.builder()
                    .tableName(tableName)
                    .indexName("year-index")
                    .keyConditionExpression("#year = :yearValue")
                    .expressionAttributeNames(expressionAttributesNames)
                    .expressionAttributeValues(expressionAttributeValues)
                    .build();

            System.out.println("=== Movie Titles ===");
            QueryResponse response = ddb.query(request);
            response.items()
                    .forEach(movie -> System.out.println(movie.get("title").s()));

        } catch (DynamoDbException e) {
            System.err.println(e.getMessage());
            System.exit(1);
        }
    }
}

• APIEinzelheiten finden Sie unter Query in AWS SDK for Java 2.x APIReference.

Scan

Das folgende Codebeispiel zeigt die VerwendungScan.

SDKfür Java 2.x

Anmerkung

Es gibt noch mehr dazu. GitHub Sie sehen das vollständige Beispiel und erfahren, wie Sie das AWS -Code-Beispiel-Repository einrichten und ausführen.

Scannt eine Amazon DynamoDB-Tabelle mit. DynamoDbClient

import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.dynamodb.DynamoDbClient;
import software.amazon.awssdk.services.dynamodb.model.AttributeValue;
import software.amazon.awssdk.services.dynamodb.model.DynamoDbException;
import software.amazon.awssdk.services.dynamodb.model.ScanRequest;
import software.amazon.awssdk.services.dynamodb.model.ScanResponse;
import java.util.Map;
import java.util.Set;

/**
 * Before running this Java V2 code example, set up your development
 * environment, including your credentials.
 *
 * For more information, see the following documentation topic:
 *
 * https://docs.aws.amazon.com/sdk-for-java/latest/developer-guide/get-started.html
 *
 * To scan items from an Amazon DynamoDB table using the AWS SDK for Java V2,
 * its better practice to use the
 * Enhanced Client, See the EnhancedScanRecords example.
 */

public class DynamoDBScanItems {
    public static void main(String[] args) {

        final String usage = """

                Usage:
                    <tableName>

                Where:
                    tableName - The Amazon DynamoDB table to get information from (for example, Music3).
                """;

        if (args.length != 1) {
            System.out.println(usage);
            System.exit(1);
        }

        String tableName = args[0];
        Region region = Region.US_EAST_1;
        DynamoDbClient ddb = DynamoDbClient.builder()
                .region(region)
                .build();

        scanItems(ddb, tableName);
        ddb.close();
    }

    public static void scanItems(DynamoDbClient ddb, String tableName) {
        try {
            ScanRequest scanRequest = ScanRequest.builder()
                    .tableName(tableName)
                    .build();

            ScanResponse response = ddb.scan(scanRequest);
            for (Map<String, AttributeValue> item : response.items()) {
                Set<String> keys = item.keySet();
                for (String key : keys) {
                    System.out.println("The key name is " + key + "\n");
                    System.out.println("The value is " + item.get(key).s());
                }
            }

        } catch (DynamoDbException e) {
            e.printStackTrace();
            System.exit(1);
        }
    }
}

• APIEinzelheiten finden Sie unter Scan in AWS SDK for Java 2.x API Reference.

UpdateItem

Das folgende Codebeispiel zeigt die VerwendungUpdateItem.

SDKfür Java 2.x

Anmerkung

Es gibt noch mehr dazu. GitHub Sie sehen das vollständige Beispiel und erfahren, wie Sie das AWS -Code-Beispiel-Repository einrichten und ausführen.

Aktualisiert ein Element in einer Tabelle mit DynamoDbClient.

import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.dynamodb.model.DynamoDbException;
import software.amazon.awssdk.services.dynamodb.model.AttributeAction;
import software.amazon.awssdk.services.dynamodb.model.AttributeValue;
import software.amazon.awssdk.services.dynamodb.model.AttributeValueUpdate;
import software.amazon.awssdk.services.dynamodb.model.UpdateItemRequest;
import software.amazon.awssdk.services.dynamodb.DynamoDbClient;
import java.util.HashMap;

/**
 * Before running this Java V2 code example, set up your development
 * environment, including your credentials.
 *
 * For more information, see the following documentation topic:
 *
 * https://docs.aws.amazon.com/sdk-for-java/latest/developer-guide/get-started.html
 *
 * To update an Amazon DynamoDB table using the AWS SDK for Java V2, its better
 * practice to use the
 * Enhanced Client, See the EnhancedModifyItem example.
 */
public class UpdateItem {
    public static void main(String[] args) {
        final String usage = """

                Usage:
                    <tableName> <key> <keyVal> <name> <updateVal>

                Where:
                    tableName - The Amazon DynamoDB table (for example, Music3).
                    key - The name of the key in the table (for example, Artist).
                    keyVal - The value of the key (for example, Famous Band).
                    name - The name of the column where the value is updated (for example, Awards).
                    updateVal - The value used to update an item (for example, 14).
                 Example:
                    UpdateItem Music3 Artist Famous Band Awards 14
                """;

        if (args.length != 5) {
            System.out.println(usage);
            System.exit(1);
        }

        String tableName = args[0];
        String key = args[1];
        String keyVal = args[2];
        String name = args[3];
        String updateVal = args[4];

        Region region = Region.US_EAST_1;
        DynamoDbClient ddb = DynamoDbClient.builder()
                .region(region)
                .build();
        updateTableItem(ddb, tableName, key, keyVal, name, updateVal);
        ddb.close();
    }

    public static void updateTableItem(DynamoDbClient ddb,
            String tableName,
            String key,
            String keyVal,
            String name,
            String updateVal) {

        HashMap<String, AttributeValue> itemKey = new HashMap<>();
        itemKey.put(key, AttributeValue.builder()
                .s(keyVal)
                .build());

        HashMap<String, AttributeValueUpdate> updatedValues = new HashMap<>();
        updatedValues.put(name, AttributeValueUpdate.builder()
                .value(AttributeValue.builder().s(updateVal).build())
                .action(AttributeAction.PUT)
                .build());

        UpdateItemRequest request = UpdateItemRequest.builder()
                .tableName(tableName)
                .key(itemKey)
                .attributeUpdates(updatedValues)
                .build();

        try {
            ddb.updateItem(request);
        } catch (DynamoDbException e) {
            System.err.println(e.getMessage());
            System.exit(1);
        }
        System.out.println("The Amazon DynamoDB table was updated!");
    }
}

• APIEinzelheiten finden Sie UpdateItemunter AWS SDK for Java 2.x APIReferenz.

UpdateTimeToLive

Das folgende Codebeispiel zeigt die VerwendungUpdateTimeToLive.

SDKfür Java 2.x

Aktiviert TTL in einer vorhandenen DynamoDB-Tabelle.

import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.dynamodb.DynamoDbClient;
import software.amazon.awssdk.services.dynamodb.model.DynamoDbException;
import software.amazon.awssdk.services.dynamodb.model.ResourceNotFoundException;
import software.amazon.awssdk.services.dynamodb.model.TimeToLiveSpecification;
import software.amazon.awssdk.services.dynamodb.model.UpdateTimeToLiveRequest;
import software.amazon.awssdk.services.dynamodb.model.UpdateTimeToLiveResponse;

import java.util.Optional;

        final TimeToLiveSpecification ttlSpecification = TimeToLiveSpecification.builder()
                .attributeName(ttlAttributeName)
                .enabled(true)
                .build();
        final UpdateTimeToLiveRequest request = UpdateTimeToLiveRequest.builder()
                .tableName(tableName)
                .timeToLiveSpecification(ttlSpecification)
                .build();
        try (DynamoDbClient ddb = DynamoDbClient.builder()
                .region(region)
                .build()) {
                final UpdateTimeToLiveResponse response = ddb.updateTimeToLive(request);
                System.out.println(tableName + " had its TTL successfully updated. The request id is "
                        + response.responseMetadata().requestId());
        } catch (ResourceNotFoundException e) {
                System.err.format("Error: The Amazon DynamoDB table \"%s\" can't be found.\n", tableName);
                System.exit(1);
        } catch (DynamoDbException e) {
                System.err.println(e.getMessage());
                System.exit(1);
        }
        System.out.println("Done!");

In TTL einer vorhandenen DynamoDB-Tabelle deaktivieren.

import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.dynamodb.DynamoDbClient;
import software.amazon.awssdk.services.dynamodb.model.DynamoDbException;
import software.amazon.awssdk.services.dynamodb.model.ResourceNotFoundException;
import software.amazon.awssdk.services.dynamodb.model.TimeToLiveSpecification;
import software.amazon.awssdk.services.dynamodb.model.UpdateTimeToLiveRequest;
import software.amazon.awssdk.services.dynamodb.model.UpdateTimeToLiveResponse;

import java.util.Optional;

        final Region region = Optional.ofNullable(args[2]).isEmpty() ? Region.US_EAST_1 : Region.of(args[2]);
        final TimeToLiveSpecification ttlSpecification = TimeToLiveSpecification.builder()
                .attributeName(ttlAttributeName)
                .enabled(false)
                .build();
        final UpdateTimeToLiveRequest request = UpdateTimeToLiveRequest.builder()
                .tableName(tableName)
                .timeToLiveSpecification(ttlSpecification)
                .build();
        try (DynamoDbClient ddb = DynamoDbClient.builder()
                .region(region)
                .build()) {
            final UpdateTimeToLiveResponse response = ddb.updateTimeToLive(request);
            System.out.println(tableName + " had its TTL successfully updated. The request id is "
                    + response.responseMetadata().requestId());
        } catch (ResourceNotFoundException e) {
            System.err.format("Error: The Amazon DynamoDB table \"%s\" can't be found.\n", tableName);
            System.exit(1);
        } catch (DynamoDbException e) {
            System.err.println(e.getMessage());
            System.exit(1);
        }
        System.out.println("Done!");

• APIEinzelheiten finden Sie unter Referenz UpdateTimeToLive.AWS SDK for Java 2.x API

Szenarien

Aktualisieren Sie die eines Artikels unter bestimmten Bedingungen TTL

Das folgende Codebeispiel zeigt, wie ein Artikel bedingt aktualisiert wird. TTL

SDKfür Java 2.x

// Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
// SPDX-License-Identifier: Apache-2.0
package com.amazon.samplelib.ttl;

import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.dynamodb.DynamoDbClient;
import software.amazon.awssdk.services.dynamodb.model.AttributeValue;
import software.amazon.awssdk.services.dynamodb.model.DynamoDbException;
import software.amazon.awssdk.services.dynamodb.model.ResourceNotFoundException;
import software.amazon.awssdk.services.dynamodb.model.UpdateItemRequest;
import software.amazon.awssdk.services.dynamodb.model.UpdateItemResponse;
import software.amazon.awssdk.utils.ImmutableMap;

import java.util.Map;
import java.util.Optional;

public class UpdateTTLConditional {
    public static void main(String[] args) {
        final String usage = """
                Usage:
                    <tableName> <primaryKey> <sortKey> <newTtlAttribute> <region>
                Where:
                    tableName - The Amazon DynamoDB table being queried.
                    primaryKey - The name of the primary key. Also known as the hash or partition key.
                    sortKey - The name of the sort key. Also known as the range attribute.
                    newTtlAttribute - New attribute name (as part of the update command)
                    region (optional) - The AWS region that the Amazon DynamoDB table is located in. (Default: us-east-1)
                """;
        // Optional "region" parameter - if args list length is NOT 3 or 4, short-circuit exit.
        if (!(args.length == 4 || args.length == 5)) {
            System.out.println(usage);
            System.exit(1);
        }
        final String tableName = args[0];
        final String primaryKey = args[1];
        final String sortKey = args[2];
        final String newTtlAttribute = args[3];
        Region region = Optional.ofNullable(args[4]).isEmpty() ? Region.US_EAST_1 : Region.of(args[4]);

        // Get current time in epoch second format
        final long currentTime = System.currentTimeMillis() / 1000;
        // Calculate expiration time 90 days from now in epoch second format
        final long expireDate = currentTime + (90 * 24 * 60 * 60);
        // An expression that defines one or more attributes to be updated, the action to be performed on them, and new values for them.
        final String updateExpression = "SET newTtlAttribute = :val1";
        // A condition that must be satisfied in order for a conditional update to succeed.
        final String conditionExpression = "expireAt > :val2";

        final ImmutableMap<String, AttributeValue> keyMap =
                ImmutableMap.of("primaryKey", AttributeValue.fromS(primaryKey),
                        "sortKey", AttributeValue.fromS(sortKey));
        final Map<String, AttributeValue> expressionAttributeValues = ImmutableMap.of(
                ":val1", AttributeValue.builder().s(newTtlAttribute).build(),
                ":val2", AttributeValue.builder().s(String.valueOf(expireDate)).build()
        );

        final UpdateItemRequest request = UpdateItemRequest.builder()
                .tableName(tableName)
                .key(keyMap)
                .updateExpression(updateExpression)
                .conditionExpression(conditionExpression)
                .expressionAttributeValues(expressionAttributeValues)
                .build();
        try (DynamoDbClient ddb = DynamoDbClient.builder()
                .region(region)
                .build()) {
            final UpdateItemResponse response = ddb.updateItem(request);
            System.out.println(tableName + " UpdateItem operation with conditional TTL successful. Request id is "
                    + response.responseMetadata().requestId());
        } catch (ResourceNotFoundException e) {
            System.err.format("Error: The Amazon DynamoDB table \"%s\" can't be found.\n", tableName);
            System.exit(1);
        } catch (DynamoDbException e) {
            System.err.println(e.getMessage());
            System.exit(1);
        }
        System.exit(0);
    }
}

• APIEinzelheiten finden Sie unter UpdateItem AWS SDK for Java 2.xAPIReferenz.

Erstellen Sie einen Artikel mit einem TTL

Das folgende Codebeispiel zeigt, wie Sie ein Element mit erstellenTTL.

SDKfür Java 2.x

// Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
// SPDX-License-Identifier: Apache-2.0

package com.amazon.samplelib.ttl;

import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.dynamodb.DynamoDbClient;
import software.amazon.awssdk.services.dynamodb.model.AttributeValue;
import software.amazon.awssdk.services.dynamodb.model.DynamoDbException;
import software.amazon.awssdk.services.dynamodb.model.PutItemRequest;
import software.amazon.awssdk.services.dynamodb.model.PutItemResponse;
import software.amazon.awssdk.services.dynamodb.model.ResourceNotFoundException;
import software.amazon.awssdk.utils.ImmutableMap;

import java.io.Serializable;
import java.util.Map;
import java.util.Optional;

public class CreateTTL {
    public static void main(String[] args) {
        final String usage = """
                Usage:
                    <tableName> <primaryKey> <sortKey> <region>
                Where:
                    tableName - The Amazon DynamoDB table being queried.
                    primaryKey - The name of the primary key. Also known as the hash or partition key.
                    sortKey - The name of the sort key. Also known as the range attribute.
                    region (optional) - The AWS region that the Amazon DynamoDB table is located in. (Default: us-east-1)
                """;
        // Optional "region" parameter - if args list length is NOT 3 or 4, short-circuit exit.
        if (!(args.length == 3 || args.length == 4)) {
            System.out.println(usage);
            System.exit(1);
        }

        String tableName = args[0];
        String primaryKey = args[1];
        String sortKey = args[2];
        Region region = Optional.ofNullable(args[3]).isEmpty() ? Region.US_EAST_1 : Region.of(args[3]);

        // Get current time in epoch second format
        final long createDate = System.currentTimeMillis() / 1000;

        // Calculate expiration time 90 days from now in epoch second format
        final long expireDate = createDate + (90 * 24 * 60 * 60);

        final ImmutableMap<String, ? extends Serializable> itemMap =
                ImmutableMap.of("primaryKey", primaryKey,
                "sortKey", sortKey,
                "creationDate", createDate,
                "expireAt", expireDate);
        final PutItemRequest request = PutItemRequest.builder()
                .tableName(tableName)
                .item((Map<String, AttributeValue>) itemMap)
                .build();
        try (DynamoDbClient ddb = DynamoDbClient.builder()
                .region(region)
                .build()) {
            final PutItemResponse response = ddb.putItem(request);
            System.out.println(tableName + " PutItem operation with TTL successful. Request id is "
                    + response.responseMetadata().requestId());
        } catch (ResourceNotFoundException e) {
            System.err.format("Error: The Amazon DynamoDB table \"%s\" can't be found.\n", tableName);
            System.exit(1);
        } catch (DynamoDbException e) {
            System.err.println(e.getMessage());
            System.exit(1);
        }
        System.exit(0);
    }
}

• APIEinzelheiten finden Sie unter PutItem AWS SDK for Java 2.xAPIReferenz.

Erste Schritte mit Tabellen, Elementen und Abfragen

Wie das aussehen kann, sehen Sie am nachfolgenden Beispielcode:

• Erstellen einer Tabelle, die Filmdaten enthalten kann.

• Einfügen, Abrufen und Aktualisieren eines einzelnen Films in der Tabelle.

• Schreibt Filmdaten aus einer JSON Beispieldatei in die Tabelle.

• Abfragen nach Filmen, die in einem bestimmten Jahr veröffentlicht wurden.

• Scan nach Filmen, die in mehreren Jahren veröffentlicht wurden.

• Löschen eines Films aus der Tabelle und anschließendes Löschen der Tabelle.

SDKfür Java 2.x

Anmerkung

Es gibt noch mehr dazu. GitHub Sie sehen das vollständige Beispiel und erfahren, wie Sie das AWS -Code-Beispiel-Repository einrichten und ausführen.

Erstellen Sie eine DynamoDB-Tabelle.

    // Create a table with a Sort key.
    public static void createTable(DynamoDbClient ddb, String tableName) {
        DynamoDbWaiter dbWaiter = ddb.waiter();
        ArrayList<AttributeDefinition> attributeDefinitions = new ArrayList<>();

        // Define attributes.
        attributeDefinitions.add(AttributeDefinition.builder()
                .attributeName("year")
                .attributeType("N")
                .build());

        attributeDefinitions.add(AttributeDefinition.builder()
                .attributeName("title")
                .attributeType("S")
                .build());

        ArrayList<KeySchemaElement> tableKey = new ArrayList<>();
        KeySchemaElement key = KeySchemaElement.builder()
                .attributeName("year")
                .keyType(KeyType.HASH)
                .build();

        KeySchemaElement key2 = KeySchemaElement.builder()
                .attributeName("title")
                .keyType(KeyType.RANGE)
                .build();

        // Add KeySchemaElement objects to the list.
        tableKey.add(key);
        tableKey.add(key2);

        CreateTableRequest request = CreateTableRequest.builder()
                .keySchema(tableKey)
                .provisionedThroughput(ProvisionedThroughput.builder()
                        .readCapacityUnits(10L)
                        .writeCapacityUnits(10L)
                        .build())
                .attributeDefinitions(attributeDefinitions)
                .tableName(tableName)
                .build();

        try {
            CreateTableResponse response = ddb.createTable(request);
            DescribeTableRequest tableRequest = DescribeTableRequest.builder()
                    .tableName(tableName)
                    .build();

            // Wait until the Amazon DynamoDB table is created.
            WaiterResponse<DescribeTableResponse> waiterResponse = dbWaiter.waitUntilTableExists(tableRequest);
            waiterResponse.matched().response().ifPresent(System.out::println);
            String newTable = response.tableDescription().tableName();
            System.out.println("The " + newTable + " was successfully created.");

        } catch (DynamoDbException e) {
            System.err.println(e.getMessage());
            System.exit(1);
        }
    }

Erstellen Sie eine Hilfsfunktion zum Herunterladen und Extrahieren der JSON Beispieldatei.

    // Load data into the table.
    public static void loadData(DynamoDbClient ddb, String tableName, String fileName) throws IOException {
        DynamoDbEnhancedClient enhancedClient = DynamoDbEnhancedClient.builder()
                .dynamoDbClient(ddb)
                .build();

        DynamoDbTable<Movies> mappedTable = enhancedClient.table("Movies", TableSchema.fromBean(Movies.class));
        JsonParser parser = new JsonFactory().createParser(new File(fileName));
        com.fasterxml.jackson.databind.JsonNode rootNode = new ObjectMapper().readTree(parser);
        Iterator<JsonNode> iter = rootNode.iterator();
        ObjectNode currentNode;
        int t = 0;
        while (iter.hasNext()) {
            // Only add 200 Movies to the table.
            if (t == 200)
                break;
            currentNode = (ObjectNode) iter.next();

            int year = currentNode.path("year").asInt();
            String title = currentNode.path("title").asText();
            String info = currentNode.path("info").toString();

            Movies movies = new Movies();
            movies.setYear(year);
            movies.setTitle(title);
            movies.setInfo(info);

            // Put the data into the Amazon DynamoDB Movie table.
            mappedTable.putItem(movies);
            t++;
        }
    }

Rufen Sie ein Element aus einer Tabelle ab.

    public static void getItem(DynamoDbClient ddb) {

        HashMap<String, AttributeValue> keyToGet = new HashMap<>();
        keyToGet.put("year", AttributeValue.builder()
                .n("1933")
                .build());

        keyToGet.put("title", AttributeValue.builder()
                .s("King Kong")
                .build());

        GetItemRequest request = GetItemRequest.builder()
                .key(keyToGet)
                .tableName("Movies")
                .build();

        try {
            Map<String, AttributeValue> returnedItem = ddb.getItem(request).item();

            if (returnedItem != null) {
                Set<String> keys = returnedItem.keySet();
                System.out.println("Amazon DynamoDB table attributes: \n");

                for (String key1 : keys) {
                    System.out.format("%s: %s\n", key1, returnedItem.get(key1).toString());
                }
            } else {
                System.out.format("No item found with the key %s!\n", "year");
            }

        } catch (DynamoDbException e) {
            System.err.println(e.getMessage());
            System.exit(1);
        }
    }

Vollständiges Beispiel.

/**
 * Before running this Java V2 code example, set up your development
 * environment, including your credentials.
 *
 * For more information, see the following documentation topic:
 *
 * https://docs.aws.amazon.com/sdk-for-java/latest/developer-guide/get-started.html
 *
 * This Java example performs these tasks:
 *
 * 1. Creates the Amazon DynamoDB Movie table with partition and sort key.
 * 2. Puts data into the Amazon DynamoDB table from a JSON document using the
 * Enhanced client.
 * 3. Gets data from the Movie table.
 * 4. Adds a new item.
 * 5. Updates an item.
 * 6. Uses a Scan to query items using the Enhanced client.
 * 7. Queries all items where the year is 2013 using the Enhanced Client.
 * 8. Deletes the table.
 */

public class Scenario {
    public static final String DASHES = new String(new char[80]).replace("\0", "-");

    public static void main(String[] args) throws IOException {
        final String usage = """

                Usage:
                    <fileName>

                Where:
                    fileName - The path to the moviedata.json file that you can download from the Amazon DynamoDB Developer Guide.
                """;

        if (args.length != 1) {
            System.out.println(usage);
            System.exit(1);
        }

        String tableName = "Movies";
        String fileName = args[0];
        Region region = Region.US_EAST_1;
        DynamoDbClient ddb = DynamoDbClient.builder()
                .region(region)
                .build();

        System.out.println(DASHES);
        System.out.println("Welcome to the Amazon DynamoDB example scenario.");
        System.out.println(DASHES);

        System.out.println(DASHES);
        System.out.println(
                "1. Creating an Amazon DynamoDB table named Movies with a key named year and a sort key named title.");
        createTable(ddb, tableName);
        System.out.println(DASHES);

        System.out.println(DASHES);
        System.out.println("2. Loading data into the Amazon DynamoDB table.");
        loadData(ddb, tableName, fileName);
        System.out.println(DASHES);

        System.out.println(DASHES);
        System.out.println("3. Getting data from the Movie table.");
        getItem(ddb);
        System.out.println(DASHES);

        System.out.println(DASHES);
        System.out.println("4. Putting a record into the Amazon DynamoDB table.");
        putRecord(ddb);
        System.out.println(DASHES);

        System.out.println(DASHES);
        System.out.println("5. Updating a record.");
        updateTableItem(ddb, tableName);
        System.out.println(DASHES);

        System.out.println(DASHES);
        System.out.println("6. Scanning the Amazon DynamoDB table.");
        scanMovies(ddb, tableName);
        System.out.println(DASHES);

        System.out.println(DASHES);
        System.out.println("7. Querying the Movies released in 2013.");
        queryTable(ddb);
        System.out.println(DASHES);

        System.out.println(DASHES);
        System.out.println("8. Deleting the Amazon DynamoDB table.");
        deleteDynamoDBTable(ddb, tableName);
        System.out.println(DASHES);

        ddb.close();
    }

    // Create a table with a Sort key.
    public static void createTable(DynamoDbClient ddb, String tableName) {
        DynamoDbWaiter dbWaiter = ddb.waiter();
        ArrayList<AttributeDefinition> attributeDefinitions = new ArrayList<>();

        // Define attributes.
        attributeDefinitions.add(AttributeDefinition.builder()
                .attributeName("year")
                .attributeType("N")
                .build());

        attributeDefinitions.add(AttributeDefinition.builder()
                .attributeName("title")
                .attributeType("S")
                .build());

        ArrayList<KeySchemaElement> tableKey = new ArrayList<>();
        KeySchemaElement key = KeySchemaElement.builder()
                .attributeName("year")
                .keyType(KeyType.HASH)
                .build();

        KeySchemaElement key2 = KeySchemaElement.builder()
                .attributeName("title")
                .keyType(KeyType.RANGE)
                .build();

        // Add KeySchemaElement objects to the list.
        tableKey.add(key);
        tableKey.add(key2);

        CreateTableRequest request = CreateTableRequest.builder()
                .keySchema(tableKey)
                .provisionedThroughput(ProvisionedThroughput.builder()
                        .readCapacityUnits(10L)
                        .writeCapacityUnits(10L)
                        .build())
                .attributeDefinitions(attributeDefinitions)
                .tableName(tableName)
                .build();

        try {
            CreateTableResponse response = ddb.createTable(request);
            DescribeTableRequest tableRequest = DescribeTableRequest.builder()
                    .tableName(tableName)
                    .build();

            // Wait until the Amazon DynamoDB table is created.
            WaiterResponse<DescribeTableResponse> waiterResponse = dbWaiter.waitUntilTableExists(tableRequest);
            waiterResponse.matched().response().ifPresent(System.out::println);
            String newTable = response.tableDescription().tableName();
            System.out.println("The " + newTable + " was successfully created.");

        } catch (DynamoDbException e) {
            System.err.println(e.getMessage());
            System.exit(1);
        }
    }

    // Query the table.
    public static void queryTable(DynamoDbClient ddb) {
        try {
            DynamoDbEnhancedClient enhancedClient = DynamoDbEnhancedClient.builder()
                    .dynamoDbClient(ddb)
                    .build();

            DynamoDbTable<Movies> custTable = enhancedClient.table("Movies", TableSchema.fromBean(Movies.class));
            QueryConditional queryConditional = QueryConditional
                    .keyEqualTo(Key.builder()
                            .partitionValue(2013)
                            .build());

            // Get items in the table and write out the ID value.
            Iterator<Movies> results = custTable.query(queryConditional).items().iterator();
            String result = "";

            while (results.hasNext()) {
                Movies rec = results.next();
                System.out.println("The title of the movie is " + rec.getTitle());
                System.out.println("The movie information  is " + rec.getInfo());
            }

        } catch (DynamoDbException e) {
            System.err.println(e.getMessage());
            System.exit(1);
        }
    }

    // Scan the table.
    public static void scanMovies(DynamoDbClient ddb, String tableName) {
        System.out.println("******* Scanning all movies.\n");
        try {
            DynamoDbEnhancedClient enhancedClient = DynamoDbEnhancedClient.builder()
                    .dynamoDbClient(ddb)
                    .build();

            DynamoDbTable<Movies> custTable = enhancedClient.table("Movies", TableSchema.fromBean(Movies.class));
            Iterator<Movies> results = custTable.scan().items().iterator();
            while (results.hasNext()) {
                Movies rec = results.next();
                System.out.println("The movie title is " + rec.getTitle());
                System.out.println("The movie year is " + rec.getYear());
            }

        } catch (DynamoDbException e) {
            System.err.println(e.getMessage());
            System.exit(1);
        }
    }

    // Load data into the table.
    public static void loadData(DynamoDbClient ddb, String tableName, String fileName) throws IOException {
        DynamoDbEnhancedClient enhancedClient = DynamoDbEnhancedClient.builder()
                .dynamoDbClient(ddb)
                .build();

        DynamoDbTable<Movies> mappedTable = enhancedClient.table("Movies", TableSchema.fromBean(Movies.class));
        JsonParser parser = new JsonFactory().createParser(new File(fileName));
        com.fasterxml.jackson.databind.JsonNode rootNode = new ObjectMapper().readTree(parser);
        Iterator<JsonNode> iter = rootNode.iterator();
        ObjectNode currentNode;
        int t = 0;
        while (iter.hasNext()) {
            // Only add 200 Movies to the table.
            if (t == 200)
                break;
            currentNode = (ObjectNode) iter.next();

            int year = currentNode.path("year").asInt();
            String title = currentNode.path("title").asText();
            String info = currentNode.path("info").toString();

            Movies movies = new Movies();
            movies.setYear(year);
            movies.setTitle(title);
            movies.setInfo(info);

            // Put the data into the Amazon DynamoDB Movie table.
            mappedTable.putItem(movies);
            t++;
        }
    }

    // Update the record to include show only directors.
    public static void updateTableItem(DynamoDbClient ddb, String tableName) {
        HashMap<String, AttributeValue> itemKey = new HashMap<>();
        itemKey.put("year", AttributeValue.builder().n("1933").build());
        itemKey.put("title", AttributeValue.builder().s("King Kong").build());

        HashMap<String, AttributeValueUpdate> updatedValues = new HashMap<>();
        updatedValues.put("info", AttributeValueUpdate.builder()
                .value(AttributeValue.builder().s("{\"directors\":[\"Merian C. Cooper\",\"Ernest B. Schoedsack\"]")
                        .build())
                .action(AttributeAction.PUT)
                .build());

        UpdateItemRequest request = UpdateItemRequest.builder()
                .tableName(tableName)
                .key(itemKey)
                .attributeUpdates(updatedValues)
                .build();

        try {
            ddb.updateItem(request);
        } catch (ResourceNotFoundException e) {
            System.err.println(e.getMessage());
            System.exit(1);
        } catch (DynamoDbException e) {
            System.err.println(e.getMessage());
            System.exit(1);
        }

        System.out.println("Item was updated!");
    }

    public static void deleteDynamoDBTable(DynamoDbClient ddb, String tableName) {
        DeleteTableRequest request = DeleteTableRequest.builder()
                .tableName(tableName)
                .build();

        try {
            ddb.deleteTable(request);

        } catch (DynamoDbException e) {
            System.err.println(e.getMessage());
            System.exit(1);
        }
        System.out.println(tableName + " was successfully deleted!");
    }

    public static void putRecord(DynamoDbClient ddb) {
        try {
            DynamoDbEnhancedClient enhancedClient = DynamoDbEnhancedClient.builder()
                    .dynamoDbClient(ddb)
                    .build();

            DynamoDbTable<Movies> table = enhancedClient.table("Movies", TableSchema.fromBean(Movies.class));

            // Populate the Table.
            Movies record = new Movies();
            record.setYear(2020);
            record.setTitle("My Movie2");
            record.setInfo("no info");
            table.putItem(record);

        } catch (DynamoDbException e) {
            System.err.println(e.getMessage());
            System.exit(1);
        }
        System.out.println("Added a new movie to the table.");
    }

    public static void getItem(DynamoDbClient ddb) {

        HashMap<String, AttributeValue> keyToGet = new HashMap<>();
        keyToGet.put("year", AttributeValue.builder()
                .n("1933")
                .build());

        keyToGet.put("title", AttributeValue.builder()
                .s("King Kong")
                .build());

        GetItemRequest request = GetItemRequest.builder()
                .key(keyToGet)
                .tableName("Movies")
                .build();

        try {
            Map<String, AttributeValue> returnedItem = ddb.getItem(request).item();

            if (returnedItem != null) {
                Set<String> keys = returnedItem.keySet();
                System.out.println("Amazon DynamoDB table attributes: \n");

                for (String key1 : keys) {
                    System.out.format("%s: %s\n", key1, returnedItem.get(key1).toString());
                }
            } else {
                System.out.format("No item found with the key %s!\n", "year");
            }

        } catch (DynamoDbException e) {
            System.err.println(e.getMessage());
            System.exit(1);
        }
    }
}

• APIEinzelheiten finden Sie unter den folgenden Themen in der AWS SDK for Java 2.x APIReferenz.

  • BatchWriteItem

  • CreateTable

  • DeleteItem

  • DeleteTable

  • DescribeTable

  • GetItem

  • PutItem

  • Abfrage

  • Scan

  • UpdateItem

Abfragen einer Tabelle mithilfe von Stapeln von PartiQL-Anweisungen

Wie das aussehen kann, sehen Sie am nachfolgenden Beispielcode:

• Rufen Sie einen Stapel von Elementen ab, indem Sie mehrere SELECT Anweisungen ausführen.

• Fügen Sie einen Stapel von Elementen hinzu, indem Sie mehrere INSERT Anweisungen ausführen.

• Aktualisieren Sie einen Stapel von Elementen, indem Sie mehrere UPDATE Anweisungen ausführen.

• Löschen Sie einen Stapel von Elementen, indem Sie mehrere DELETE Anweisungen ausführen.

SDKfür Java 2.x

Anmerkung

Es gibt noch mehr dazu. GitHub Sie sehen das vollständige Beispiel und erfahren, wie Sie das AWS -Code-Beispiel-Repository einrichten und ausführen.

public class ScenarioPartiQLBatch {
        public static void main(String[] args) throws IOException {
                String tableName = "MoviesPartiQBatch";
                Region region = Region.US_EAST_1;
                DynamoDbClient ddb = DynamoDbClient.builder()
                                .region(region)
                                .build();

                System.out.println("******* Creating an Amazon DynamoDB table named " + tableName
                                + " with a key named year and a sort key named title.");
                createTable(ddb, tableName);

                System.out.println("******* Adding multiple records into the " + tableName
                                + " table using a batch command.");
                putRecordBatch(ddb);

                System.out.println("******* Updating multiple records using a batch command.");
                updateTableItemBatch(ddb);

                System.out.println("******* Deleting multiple records using a batch command.");
                deleteItemBatch(ddb);

                System.out.println("******* Deleting the Amazon DynamoDB table.");
                deleteDynamoDBTable(ddb, tableName);
                ddb.close();
        }

        public static void createTable(DynamoDbClient ddb, String tableName) {
                DynamoDbWaiter dbWaiter = ddb.waiter();
                ArrayList<AttributeDefinition> attributeDefinitions = new ArrayList<>();

                // Define attributes.
                attributeDefinitions.add(AttributeDefinition.builder()
                                .attributeName("year")
                                .attributeType("N")
                                .build());

                attributeDefinitions.add(AttributeDefinition.builder()
                                .attributeName("title")
                                .attributeType("S")
                                .build());

                ArrayList<KeySchemaElement> tableKey = new ArrayList<>();
                KeySchemaElement key = KeySchemaElement.builder()
                                .attributeName("year")
                                .keyType(KeyType.HASH)
                                .build();

                KeySchemaElement key2 = KeySchemaElement.builder()
                                .attributeName("title")
                                .keyType(KeyType.RANGE) // Sort
                                .build();

                // Add KeySchemaElement objects to the list.
                tableKey.add(key);
                tableKey.add(key2);

                CreateTableRequest request = CreateTableRequest.builder()
                                .keySchema(tableKey)
                                .provisionedThroughput(ProvisionedThroughput.builder()
                                                .readCapacityUnits(new Long(10))
                                                .writeCapacityUnits(new Long(10))
                                                .build())
                                .attributeDefinitions(attributeDefinitions)
                                .tableName(tableName)
                                .build();

                try {
                        CreateTableResponse response = ddb.createTable(request);
                        DescribeTableRequest tableRequest = DescribeTableRequest.builder()
                                        .tableName(tableName)
                                        .build();

                        // Wait until the Amazon DynamoDB table is created.
                        WaiterResponse<DescribeTableResponse> waiterResponse = dbWaiter
                                        .waitUntilTableExists(tableRequest);
                        waiterResponse.matched().response().ifPresent(System.out::println);
                        String newTable = response.tableDescription().tableName();
                        System.out.println("The " + newTable + " was successfully created.");

                } catch (DynamoDbException e) {
                        System.err.println(e.getMessage());
                        System.exit(1);
                }
        }

        public static void putRecordBatch(DynamoDbClient ddb) {
                String sqlStatement = "INSERT INTO MoviesPartiQBatch VALUE {'year':?, 'title' : ?, 'info' : ?}";
                try {
                        // Create three movies to add to the Amazon DynamoDB table.
                        // Set data for Movie 1.
                        List<AttributeValue> parameters = new ArrayList<>();

                        AttributeValue att1 = AttributeValue.builder()
                                        .n(String.valueOf("2022"))
                                        .build();

                        AttributeValue att2 = AttributeValue.builder()
                                        .s("My Movie 1")
                                        .build();

                        AttributeValue att3 = AttributeValue.builder()
                                        .s("No Information")
                                        .build();

                        parameters.add(att1);
                        parameters.add(att2);
                        parameters.add(att3);

                        BatchStatementRequest statementRequestMovie1 = BatchStatementRequest.builder()
                                        .statement(sqlStatement)
                                        .parameters(parameters)
                                        .build();

                        // Set data for Movie 2.
                        List<AttributeValue> parametersMovie2 = new ArrayList<>();
                        AttributeValue attMovie2 = AttributeValue.builder()
                                        .n(String.valueOf("2022"))
                                        .build();

                        AttributeValue attMovie2A = AttributeValue.builder()
                                        .s("My Movie 2")
                                        .build();

                        AttributeValue attMovie2B = AttributeValue.builder()
                                        .s("No Information")
                                        .build();

                        parametersMovie2.add(attMovie2);
                        parametersMovie2.add(attMovie2A);
                        parametersMovie2.add(attMovie2B);

                        BatchStatementRequest statementRequestMovie2 = BatchStatementRequest.builder()
                                        .statement(sqlStatement)
                                        .parameters(parametersMovie2)
                                        .build();

                        // Set data for Movie 3.
                        List<AttributeValue> parametersMovie3 = new ArrayList<>();
                        AttributeValue attMovie3 = AttributeValue.builder()
                                        .n(String.valueOf("2022"))
                                        .build();

                        AttributeValue attMovie3A = AttributeValue.builder()
                                        .s("My Movie 3")
                                        .build();

                        AttributeValue attMovie3B = AttributeValue.builder()
                                        .s("No Information")
                                        .build();

                        parametersMovie3.add(attMovie3);
                        parametersMovie3.add(attMovie3A);
                        parametersMovie3.add(attMovie3B);

                        BatchStatementRequest statementRequestMovie3 = BatchStatementRequest.builder()
                                        .statement(sqlStatement)
                                        .parameters(parametersMovie3)
                                        .build();

                        // Add all three movies to the list.
                        List<BatchStatementRequest> myBatchStatementList = new ArrayList<>();
                        myBatchStatementList.add(statementRequestMovie1);
                        myBatchStatementList.add(statementRequestMovie2);
                        myBatchStatementList.add(statementRequestMovie3);

                        BatchExecuteStatementRequest batchRequest = BatchExecuteStatementRequest.builder()
                                        .statements(myBatchStatementList)
                                        .build();

                        BatchExecuteStatementResponse response = ddb.batchExecuteStatement(batchRequest);
                        System.out.println("ExecuteStatement successful: " + response.toString());
                        System.out.println("Added new movies using a batch command.");

                } catch (DynamoDbException e) {
                        System.err.println(e.getMessage());
                        System.exit(1);
                }
        }

        public static void updateTableItemBatch(DynamoDbClient ddb) {
                String sqlStatement = "UPDATE MoviesPartiQBatch SET info = 'directors\":[\"Merian C. Cooper\",\"Ernest B. Schoedsack' where year=? and title=?";
                List<AttributeValue> parametersRec1 = new ArrayList<>();

                // Update three records.
                AttributeValue att1 = AttributeValue.builder()
                                .n(String.valueOf("2022"))
                                .build();

                AttributeValue att2 = AttributeValue.builder()
                                .s("My Movie 1")
                                .build();

                parametersRec1.add(att1);
                parametersRec1.add(att2);

                BatchStatementRequest statementRequestRec1 = BatchStatementRequest.builder()
                                .statement(sqlStatement)
                                .parameters(parametersRec1)
                                .build();

                // Update record 2.
                List<AttributeValue> parametersRec2 = new ArrayList<>();
                AttributeValue attRec2 = AttributeValue.builder()
                                .n(String.valueOf("2022"))
                                .build();

                AttributeValue attRec2a = AttributeValue.builder()
                                .s("My Movie 2")
                                .build();

                parametersRec2.add(attRec2);
                parametersRec2.add(attRec2a);
                BatchStatementRequest statementRequestRec2 = BatchStatementRequest.builder()
                                .statement(sqlStatement)
                                .parameters(parametersRec2)
                                .build();

                // Update record 3.
                List<AttributeValue> parametersRec3 = new ArrayList<>();
                AttributeValue attRec3 = AttributeValue.builder()
                                .n(String.valueOf("2022"))
                                .build();

                AttributeValue attRec3a = AttributeValue.builder()
                                .s("My Movie 3")
                                .build();

                parametersRec3.add(attRec3);
                parametersRec3.add(attRec3a);
                BatchStatementRequest statementRequestRec3 = BatchStatementRequest.builder()
                                .statement(sqlStatement)
                                .parameters(parametersRec3)
                                .build();

                // Add all three movies to the list.
                List<BatchStatementRequest> myBatchStatementList = new ArrayList<>();
                myBatchStatementList.add(statementRequestRec1);
                myBatchStatementList.add(statementRequestRec2);
                myBatchStatementList.add(statementRequestRec3);

                BatchExecuteStatementRequest batchRequest = BatchExecuteStatementRequest.builder()
                                .statements(myBatchStatementList)
                                .build();

                try {
                        BatchExecuteStatementResponse response = ddb.batchExecuteStatement(batchRequest);
                        System.out.println("ExecuteStatement successful: " + response.toString());
                        System.out.println("Updated three movies using a batch command.");

                } catch (DynamoDbException e) {
                        System.err.println(e.getMessage());
                        System.exit(1);
                }
                System.out.println("Item was updated!");
        }

        public static void deleteItemBatch(DynamoDbClient ddb) {
                String sqlStatement = "DELETE FROM MoviesPartiQBatch WHERE year = ? and title=?";
                List<AttributeValue> parametersRec1 = new ArrayList<>();

                // Specify three records to delete.
                AttributeValue att1 = AttributeValue.builder()
                                .n(String.valueOf("2022"))
                                .build();

                AttributeValue att2 = AttributeValue.builder()
                                .s("My Movie 1")
                                .build();

                parametersRec1.add(att1);
                parametersRec1.add(att2);

                BatchStatementRequest statementRequestRec1 = BatchStatementRequest.builder()
                                .statement(sqlStatement)
                                .parameters(parametersRec1)
                                .build();

                // Specify record 2.
                List<AttributeValue> parametersRec2 = new ArrayList<>();
                AttributeValue attRec2 = AttributeValue.builder()
                                .n(String.valueOf("2022"))
                                .build();

                AttributeValue attRec2a = AttributeValue.builder()
                                .s("My Movie 2")
                                .build();

                parametersRec2.add(attRec2);
                parametersRec2.add(attRec2a);
                BatchStatementRequest statementRequestRec2 = BatchStatementRequest.builder()
                                .statement(sqlStatement)
                                .parameters(parametersRec2)
                                .build();

                // Specify record 3.
                List<AttributeValue> parametersRec3 = new ArrayList<>();
                AttributeValue attRec3 = AttributeValue.builder()
                                .n(String.valueOf("2022"))
                                .build();

                AttributeValue attRec3a = AttributeValue.builder()
                                .s("My Movie 3")
                                .build();

                parametersRec3.add(attRec3);
                parametersRec3.add(attRec3a);

                BatchStatementRequest statementRequestRec3 = BatchStatementRequest.builder()
                                .statement(sqlStatement)
                                .parameters(parametersRec3)
                                .build();

                // Add all three movies to the list.
                List<BatchStatementRequest> myBatchStatementList = new ArrayList<>();
                myBatchStatementList.add(statementRequestRec1);
                myBatchStatementList.add(statementRequestRec2);
                myBatchStatementList.add(statementRequestRec3);

                BatchExecuteStatementRequest batchRequest = BatchExecuteStatementRequest.builder()
                                .statements(myBatchStatementList)
                                .build();

                try {
                        ddb.batchExecuteStatement(batchRequest);
                        System.out.println("Deleted three movies using a batch command.");

                } catch (DynamoDbException e) {
                        System.err.println(e.getMessage());
                        System.exit(1);
                }
        }

        public static void deleteDynamoDBTable(DynamoDbClient ddb, String tableName) {
                DeleteTableRequest request = DeleteTableRequest.builder()
                                .tableName(tableName)
                                .build();

                try {
                        ddb.deleteTable(request);

                } catch (DynamoDbException e) {
                        System.err.println(e.getMessage());
                        System.exit(1);
                }
                System.out.println(tableName + " was successfully deleted!");
        }

        private static ExecuteStatementResponse executeStatementRequest(DynamoDbClient ddb, String statement,
                        List<AttributeValue> parameters) {
                ExecuteStatementRequest request = ExecuteStatementRequest.builder()
                                .statement(statement)
                                .parameters(parameters)
                                .build();

                return ddb.executeStatement(request);
        }
}

• APIEinzelheiten finden Sie BatchExecuteStatementunter AWS SDK for Java 2.x APIReferenz.

Abfragen einer Tabelle mit PartiQL

Wie das aussehen kann, sehen Sie am nachfolgenden Beispielcode:

• Rufen Sie ein Objekt ab, indem Sie eine SELECT Anweisung ausführen.

• Fügen Sie ein Element hinzu, indem Sie eine INSERT Anweisung ausführen.

• Aktualisieren Sie ein Element, indem Sie eine UPDATE Anweisung ausführen.

• Löschen Sie ein Element, indem Sie eine DELETE Anweisung ausführen.

SDKfür Java 2.x

Anmerkung

Es gibt noch mehr dazu. GitHub Sie sehen das vollständige Beispiel und erfahren, wie Sie das AWS -Code-Beispiel-Repository einrichten und ausführen.

public class ScenarioPartiQ {
    public static void main(String[] args) throws IOException {
        final String usage = """

                Usage:
                    <fileName>

                Where:
                    fileName - The path to the moviedata.json file that you can download from the Amazon DynamoDB Developer Guide.
                """;

        if (args.length != 1) {
            System.out.println(usage);
            System.exit(1);
        }

        String fileName = args[0];
        String tableName = "MoviesPartiQ";
        Region region = Region.US_EAST_1;
        DynamoDbClient ddb = DynamoDbClient.builder()
                .region(region)
                .build();

        System.out.println(
                "******* Creating an Amazon DynamoDB table named MoviesPartiQ with a key named year and a sort key named title.");
        createTable(ddb, tableName);

        System.out.println("******* Loading data into the MoviesPartiQ table.");
        loadData(ddb, fileName);

        System.out.println("******* Getting data from the MoviesPartiQ table.");
        getItem(ddb);

        System.out.println("******* Putting a record into the MoviesPartiQ table.");
        putRecord(ddb);

        System.out.println("******* Updating a record.");
        updateTableItem(ddb);

        System.out.println("******* Querying the movies released in 2013.");
        queryTable(ddb);

        System.out.println("******* Deleting the Amazon DynamoDB table.");
        deleteDynamoDBTable(ddb, tableName);
        ddb.close();
    }

    public static void createTable(DynamoDbClient ddb, String tableName) {
        DynamoDbWaiter dbWaiter = ddb.waiter();
        ArrayList<AttributeDefinition> attributeDefinitions = new ArrayList<>();

        // Define attributes.
        attributeDefinitions.add(AttributeDefinition.builder()
                .attributeName("year")
                .attributeType("N")
                .build());

        attributeDefinitions.add(AttributeDefinition.builder()
                .attributeName("title")
                .attributeType("S")
                .build());

        ArrayList<KeySchemaElement> tableKey = new ArrayList<>();
        KeySchemaElement key = KeySchemaElement.builder()
                .attributeName("year")
                .keyType(KeyType.HASH)
                .build();

        KeySchemaElement key2 = KeySchemaElement.builder()
                .attributeName("title")
                .keyType(KeyType.RANGE) // Sort
                .build();

        // Add KeySchemaElement objects to the list.
        tableKey.add(key);
        tableKey.add(key2);

        CreateTableRequest request = CreateTableRequest.builder()
                .keySchema(tableKey)
                .provisionedThroughput(ProvisionedThroughput.builder()
                        .readCapacityUnits(new Long(10))
                        .writeCapacityUnits(new Long(10))
                        .build())
                .attributeDefinitions(attributeDefinitions)
                .tableName(tableName)
                .build();

        try {
            CreateTableResponse response = ddb.createTable(request);
            DescribeTableRequest tableRequest = DescribeTableRequest.builder()
                    .tableName(tableName)
                    .build();

            // Wait until the Amazon DynamoDB table is created.
            WaiterResponse<DescribeTableResponse> waiterResponse = dbWaiter.waitUntilTableExists(tableRequest);
            waiterResponse.matched().response().ifPresent(System.out::println);
            String newTable = response.tableDescription().tableName();
            System.out.println("The " + newTable + " was successfully created.");

        } catch (DynamoDbException e) {
            System.err.println(e.getMessage());
            System.exit(1);
        }
    }

    // Load data into the table.
    public static void loadData(DynamoDbClient ddb, String fileName) throws IOException {

        String sqlStatement = "INSERT INTO MoviesPartiQ VALUE {'year':?, 'title' : ?, 'info' : ?}";
        JsonParser parser = new JsonFactory().createParser(new File(fileName));
        com.fasterxml.jackson.databind.JsonNode rootNode = new ObjectMapper().readTree(parser);
        Iterator<JsonNode> iter = rootNode.iterator();
        ObjectNode currentNode;
        int t = 0;
        List<AttributeValue> parameters = new ArrayList<>();
        while (iter.hasNext()) {

            // Add 200 movies to the table.
            if (t == 200)
                break;
            currentNode = (ObjectNode) iter.next();

            int year = currentNode.path("year").asInt();
            String title = currentNode.path("title").asText();
            String info = currentNode.path("info").toString();

            AttributeValue att1 = AttributeValue.builder()
                    .n(String.valueOf(year))
                    .build();

            AttributeValue att2 = AttributeValue.builder()
                    .s(title)
                    .build();

            AttributeValue att3 = AttributeValue.builder()
                    .s(info)
                    .build();

            parameters.add(att1);
            parameters.add(att2);
            parameters.add(att3);

            // Insert the movie into the Amazon DynamoDB table.
            executeStatementRequest(ddb, sqlStatement, parameters);
            System.out.println("Added Movie " + title);

            parameters.remove(att1);
            parameters.remove(att2);
            parameters.remove(att3);
            t++;
        }
    }

    public static void getItem(DynamoDbClient ddb) {

        String sqlStatement = "SELECT * FROM MoviesPartiQ where year=? and title=?";
        List<AttributeValue> parameters = new ArrayList<>();
        AttributeValue att1 = AttributeValue.builder()
                .n("2012")
                .build();

        AttributeValue att2 = AttributeValue.builder()
                .s("The Perks of Being a Wallflower")
                .build();

        parameters.add(att1);
        parameters.add(att2);

        try {
            ExecuteStatementResponse response = executeStatementRequest(ddb, sqlStatement, parameters);
            System.out.println("ExecuteStatement successful: " + response.toString());

        } catch (DynamoDbException e) {
            System.err.println(e.getMessage());
            System.exit(1);
        }
    }

    public static void putRecord(DynamoDbClient ddb) {

        String sqlStatement = "INSERT INTO MoviesPartiQ VALUE {'year':?, 'title' : ?, 'info' : ?}";
        try {
            List<AttributeValue> parameters = new ArrayList<>();

            AttributeValue att1 = AttributeValue.builder()
                    .n(String.valueOf("2020"))
                    .build();

            AttributeValue att2 = AttributeValue.builder()
                    .s("My Movie")
                    .build();

            AttributeValue att3 = AttributeValue.builder()
                    .s("No Information")
                    .build();

            parameters.add(att1);
            parameters.add(att2);
            parameters.add(att3);

            executeStatementRequest(ddb, sqlStatement, parameters);
            System.out.println("Added new movie.");

        } catch (DynamoDbException e) {
            System.err.println(e.getMessage());
            System.exit(1);
        }
    }

    public static void updateTableItem(DynamoDbClient ddb) {

        String sqlStatement = "UPDATE MoviesPartiQ SET info = 'directors\":[\"Merian C. Cooper\",\"Ernest B. Schoedsack' where year=? and title=?";
        List<AttributeValue> parameters = new ArrayList<>();
        AttributeValue att1 = AttributeValue.builder()
                .n(String.valueOf("2013"))
                .build();

        AttributeValue att2 = AttributeValue.builder()
                .s("The East")
                .build();

        parameters.add(att1);
        parameters.add(att2);

        try {
            executeStatementRequest(ddb, sqlStatement, parameters);

        } catch (DynamoDbException e) {
            System.err.println(e.getMessage());
            System.exit(1);
        }
        System.out.println("Item was updated!");
    }

    // Query the table where the year is 2013.
    public static void queryTable(DynamoDbClient ddb) {
        String sqlStatement = "SELECT * FROM MoviesPartiQ where year = ? ORDER BY year";
        try {

            List<AttributeValue> parameters = new ArrayList<>();
            AttributeValue att1 = AttributeValue.builder()
                    .n(String.valueOf("2013"))
                    .build();
            parameters.add(att1);

            // Get items in the table and write out the ID value.
            ExecuteStatementResponse response = executeStatementRequest(ddb, sqlStatement, parameters);
            System.out.println("ExecuteStatement successful: " + response.toString());

        } catch (DynamoDbException e) {
            System.err.println(e.getMessage());
            System.exit(1);
        }
    }

    public static void deleteDynamoDBTable(DynamoDbClient ddb, String tableName) {

        DeleteTableRequest request = DeleteTableRequest.builder()
                .tableName(tableName)
                .build();

        try {
            ddb.deleteTable(request);

        } catch (DynamoDbException e) {
            System.err.println(e.getMessage());
            System.exit(1);
        }
        System.out.println(tableName + " was successfully deleted!");
    }

    private static ExecuteStatementResponse executeStatementRequest(DynamoDbClient ddb, String statement,
            List<AttributeValue> parameters) {
        ExecuteStatementRequest request = ExecuteStatementRequest.builder()
                .statement(statement)
                .parameters(parameters)
                .build();

        return ddb.executeStatement(request);
    }

    private static void processResults(ExecuteStatementResponse executeStatementResult) {
        System.out.println("ExecuteStatement successful: " + executeStatementResult.toString());
    }
}

• APIEinzelheiten finden Sie ExecuteStatementunter AWS SDK for Java 2.x APIReferenz.

Fragen Sie nach TTL Artikeln ab

Das folgende Codebeispiel zeigt, wie TTL Elemente abgefragt werden.

SDKfür Java 2.x

Fragen Sie den gefilterten Ausdruck ab, um TTL Elemente in einer DynamoDB-Tabelle zu sammeln.

import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.dynamodb.DynamoDbClient;
import software.amazon.awssdk.services.dynamodb.model.AttributeValue;
import software.amazon.awssdk.services.dynamodb.model.DynamoDbException;
import software.amazon.awssdk.services.dynamodb.model.QueryRequest;
import software.amazon.awssdk.services.dynamodb.model.QueryResponse;
import software.amazon.awssdk.services.dynamodb.model.ResourceNotFoundException;
import software.amazon.awssdk.utils.ImmutableMap;

import java.util.Map;
import java.util.Optional;

        // Get current time in epoch second format (comparing against expiry attribute)
        final long currentTime = System.currentTimeMillis() / 1000;

        // A string that contains conditions that DynamoDB applies after the Query operation, but before the data is returned to you.
        final String keyConditionExpression = "#pk = :pk";

        // The condition that specifies the key values for items to be retrieved by the Query action.
        final String filterExpression = "#ea > :ea";
        final Map<String, String> expressionAttributeNames = ImmutableMap.of(
                "#pk", "primaryKey",
                "#ea", "expireAt");
        final Map<String, AttributeValue> expressionAttributeValues = ImmutableMap.of(
                ":pk", AttributeValue.builder().s(primaryKey).build(),
                ":ea", AttributeValue.builder().s(String.valueOf(currentTime)).build()
        );

        final QueryRequest request = QueryRequest.builder()
                .tableName(tableName)
                .keyConditionExpression(keyConditionExpression)
                .filterExpression(filterExpression)
                .expressionAttributeNames(expressionAttributeNames)
                .expressionAttributeValues(expressionAttributeValues)
                .build();
        try (DynamoDbClient ddb = DynamoDbClient.builder()
                .region(region)
                .build()) {
            final QueryResponse response = ddb.query(request);
            System.out.println(tableName + " Query operation with TTL successful. Request id is "
                    + response.responseMetadata().requestId());
            // Print the items that are not expired
            for (Map<String, AttributeValue> item : response.items()) {
                System.out.println(item.toString());
            }
        } catch (ResourceNotFoundException e) {
            System.err.format("Error: The Amazon DynamoDB table \"%s\" can't be found.\n", tableName);
            System.exit(1);
        } catch (DynamoDbException e) {
            System.err.println(e.getMessage());
            System.exit(1);
        }
        System.exit(0);

• APIEinzelheiten finden Sie unter Query in AWS SDK for Java 2.x API Reference.

Aktualisieren Sie den eines Artikels TTL

Das folgende Codebeispiel zeigt, wie Sie einen Artikel aktualisierenTTL.

SDKfür Java 2.x

Aktualisieren Sie TTL ein vorhandenes DynamoDB-Element in einer Tabelle.

import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.dynamodb.DynamoDbClient;
import software.amazon.awssdk.services.dynamodb.model.AttributeValue;
import software.amazon.awssdk.services.dynamodb.model.DynamoDbException;
import software.amazon.awssdk.services.dynamodb.model.ResourceNotFoundException;
import software.amazon.awssdk.services.dynamodb.model.UpdateItemRequest;
import software.amazon.awssdk.services.dynamodb.model.UpdateItemResponse;
import software.amazon.awssdk.utils.ImmutableMap;

import java.util.Map;
import java.util.Optional;

        // Get current time in epoch second format
        final long currentTime = System.currentTimeMillis() / 1000;
        // Calculate expiration time 90 days from now in epoch second format
        final long expireDate = currentTime + (90 * 24 * 60 * 60);
        // An expression that defines one or more attributes to be updated, the action to be performed on them, and new values for them.
        final String updateExpression = "SET updatedAt=:c, expireAt=:e";

        final ImmutableMap<String, AttributeValue> keyMap =
                ImmutableMap.of("primaryKey", AttributeValue.fromS(primaryKey),
                        "sortKey", AttributeValue.fromS(sortKey));
        final Map<String, AttributeValue> expressionAttributeValues = ImmutableMap.of(
                ":c", AttributeValue.builder().s(String.valueOf(currentTime)).build(),
                ":e", AttributeValue.builder().s(String.valueOf(expireDate)).build()
        );

        final UpdateItemRequest request = UpdateItemRequest.builder()
                .tableName(tableName)
                .key(keyMap)
                .updateExpression(updateExpression)
                .expressionAttributeValues(expressionAttributeValues)
                .build();
        try (DynamoDbClient ddb = DynamoDbClient.builder()
                .region(region)
                .build()) {
            final UpdateItemResponse response = ddb.updateItem(request);
            System.out.println(tableName + " UpdateItem operation with TTL successful. Request id is "
                    + response.responseMetadata().requestId());
        } catch (ResourceNotFoundException e) {
            System.err.format("Error: The Amazon DynamoDB table \"%s\" can't be found.\n", tableName);
            System.exit(1);
        } catch (DynamoDbException e) {
            System.err.println(e.getMessage());
            System.exit(1);
        }
        System.exit(0);

• APIEinzelheiten finden Sie unter Referenz UpdateItem.AWS SDK for Java 2.x API

Serverless-Beispiele

Rufen Sie eine Lambda-Funktion von einem DynamoDB-Trigger aus auf

Das folgende Codebeispiel zeigt, wie eine Lambda-Funktion implementiert wird, die ein Ereignis empfängt, das durch den Empfang von Datensätzen aus einem DynamoDB-Stream ausgelöst wird. Die Funktion ruft die DynamoDB-Nutzlast ab und protokolliert den Inhalt des Datensatzes.

SDKfür Java 2.x

Anmerkung

Es gibt noch mehr dazu. GitHub Das vollständige Beispiel sowie eine Anleitung zum Einrichten und Ausführen finden Sie im Repository mit Serverless-Beispielen.

Verwenden eines DynamoDB-Ereignisses mit Lambda unter Verwendung von Java.

import com.amazonaws.services.lambda.runtime.Context;
import com.amazonaws.services.lambda.runtime.RequestHandler;
import com.amazonaws.services.lambda.runtime.events.DynamodbEvent;
import com.amazonaws.services.lambda.runtime.events.DynamodbEvent.DynamodbStreamRecord;
import com.google.gson.Gson;
import com.google.gson.GsonBuilder;

public class example implements RequestHandler<DynamodbEvent, Void> {

    private static final Gson GSON = new GsonBuilder().setPrettyPrinting().create();

    @Override
    public Void handleRequest(DynamodbEvent event, Context context) {
        System.out.println(GSON.toJson(event));
        event.getRecords().forEach(this::logDynamoDBRecord);
        return null;
    }

    private void logDynamoDBRecord(DynamodbStreamRecord record) {
        System.out.println(record.getEventID());
        System.out.println(record.getEventName());
        System.out.println("DynamoDB Record: " + GSON.toJson(record.getDynamodb()));
    }
}

Melden von Batch-Elementfehlern für Lambda-Funktionen mit einem DynamoDB-Trigger

Das folgende Codebeispiel zeigt, wie eine partielle Batch-Antwort für Lambda-Funktionen implementiert wird, die Ereignisse aus einem DynamoDB-Stream empfangen. Die Funktion meldet die Batch-Elementfehler in der Antwort und signalisiert Lambda, diese Nachrichten später erneut zu versuchen.

SDKfür Java 2.x

Anmerkung

Es gibt noch mehr dazu. GitHub Das vollständige Beispiel sowie eine Anleitung zum Einrichten und Ausführen finden Sie im Repository mit Serverless-Beispielen.

Melden von DynamoDB-Batchelementfehlern mit Lambda unter Verwendung von Java.

// Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
// SPDX-License-Identifier: Apache-2.0
import com.amazonaws.services.lambda.runtime.Context;
import com.amazonaws.services.lambda.runtime.RequestHandler;
import com.amazonaws.services.lambda.runtime.events.DynamodbEvent;
import com.amazonaws.services.lambda.runtime.events.StreamsEventResponse;
import com.amazonaws.services.lambda.runtime.events.models.dynamodb.StreamRecord;

import java.io.Serializable;
import java.util.ArrayList;
import java.util.List;

public class ProcessDynamodbRecords implements RequestHandler<DynamodbEvent, Serializable> {

    @Override
    public StreamsEventResponse handleRequest(DynamodbEvent input, Context context) {

        List<StreamsEventResponse.BatchItemFailure> batchItemFailures = new ArrayList<>();
        String curRecordSequenceNumber = "";

        for (DynamodbEvent.DynamodbStreamRecord dynamodbStreamRecord : input.getRecords()) {
          try {
                //Process your record
                StreamRecord dynamodbRecord = dynamodbStreamRecord.getDynamodb();
                curRecordSequenceNumber = dynamodbRecord.getSequenceNumber();
                
            } catch (Exception e) {
                /* Since we are working with streams, we can return the failed item immediately.
                   Lambda will immediately begin to retry processing from this failed item onwards. */
                batchItemFailures.add(new StreamsEventResponse.BatchItemFailure(curRecordSequenceNumber));
                return new StreamsEventResponse(batchItemFailures);
            }
        }
       
       return new StreamsEventResponse();   
    }
}