DynamoDBAsyncGetItem.java - AWS Code Sample


DynamoDBAsyncGetItem.java demonstrates how to get an item by using the DynamoDbAsyncClient object

/** * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved. * * This file is licensed under the Apache License, Version 2.0 (the "License"). * You may not use this file except in compliance with the License. A copy of * the License is located at * * http://aws.amazon.com/apache2.0/ * * This file is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR * CONDITIONS OF ANY KIND, either express or implied. See the License for the * specific language governing permissions and limitations under the License. * */ package com.example.dynamodbasync; import software.amazon.awssdk.regions.Region; import software.amazon.awssdk.services.dynamodb.model.GetItemRequest; import software.amazon.awssdk.services.dynamodb.model.AttributeValue; import software.amazon.awssdk.services.dynamodb.DynamoDbAsyncClient; import java.util.HashMap; import java.util.Map; import java.util.Set; import java.util.stream.Collectors; import software.amazon.awssdk.services.dynamodb.model.DynamoDbException; public class DynamoDBAsyncGetItem { public static void main(String[] args) { final String USAGE = "\n" + "Usage:\n" + " DynamoDBAsyncGetItem <table> <key> <keyVal>\n\n" + "Where:\n" + " table - the table from which an item is retrieved (i.e., Music3)\n" + " key - the key used in the table (i.e., Artist) \n" + " keyval - the key value that represents the item to get (i.e., Famous Band)\n" + " Example:\n" + " Music3 Artist Famous Band\n" + " **Warning** This program will actually retrieve an item\n" + " that you specify!\n"; if (args.length < 3) { System.out.println(USAGE); System.exit(1); } String tableName = args[0]; String key = args[1]; String keyVal = args[2]; // Create the DynamoDbAsyncClient object Region region = Region.US_WEST_2; DynamoDbAsyncClient client = DynamoDbAsyncClient.builder() .region(region) .build(); System.out.format("Retrieving item \"%s\" from \"%s\"\n", keyVal, tableName ); getItem(client, tableName, key, keyVal); } public static void getItem(DynamoDbAsyncClient client, String tableName, String key, String keyVal) { HashMap<String, AttributeValue> keyToGet = new HashMap<String, AttributeValue>(); keyToGet.put(key, AttributeValue.builder() .s(keyVal).build()); try { // Create a GetItemRequest instance GetItemRequest request = GetItemRequest.builder() .key(keyToGet) .tableName(tableName) .build(); // Invoke the DynamoDbAsyncClient object's getItem java.util.Collection<software.amazon.awssdk.services.dynamodb.model.AttributeValue> returnedItem = client.getItem(request).join().item().values(); // Convert Set to Map Map<String, AttributeValue> map = returnedItem.stream().collect(Collectors.toMap(AttributeValue::s, s->s)); Set<String> keys = map.keySet(); for (String sinKey : keys) { System.out.format("%s: %s\n", sinKey, map.get(sinKey).toString()); } } catch (DynamoDbException e) { System.err.println(e.getMessage()); System.exit(1); } } }

Sample Details

Service: DynamoDB

Last tested: 8/7/2020

Author: scmacdon-aws

Type: full-example