LowLevelItemBinaryExample.java - AWS Code Sample


/** * Copyright 2010-2019 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.amazonaws.codesamples.lowlevel; import java.io.ByteArrayInputStream; import java.io.ByteArrayOutputStream; import java.io.IOException; import java.nio.ByteBuffer; import java.text.SimpleDateFormat; import java.util.Date; import java.util.HashMap; import java.util.Map; import java.util.TimeZone; import java.util.zip.GZIPInputStream; import java.util.zip.GZIPOutputStream; import com.amazonaws.auth.profile.ProfileCredentialsProvider; import com.amazonaws.services.dynamodbv2.AmazonDynamoDBClient; import com.amazonaws.services.dynamodbv2.model.AttributeValue; import com.amazonaws.services.dynamodbv2.model.DeleteItemRequest; import com.amazonaws.services.dynamodbv2.model.GetItemRequest; import com.amazonaws.services.dynamodbv2.model.GetItemResult; import com.amazonaws.services.dynamodbv2.model.PutItemRequest; public class LowLevelItemBinaryExample { static AmazonDynamoDBClient client = new AmazonDynamoDBClient(new ProfileCredentialsProvider()); static String tableName = "Reply"; static SimpleDateFormat dateFormatter = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSS'Z'"); public static void main(String[] args) throws IOException { try { // Format the primary key values String threadId = "Amazon DynamoDB#DynamoDB Thread 2"; dateFormatter.setTimeZone(TimeZone.getTimeZone("UTC")); String replyDateTime = dateFormatter.format(new Date()); // Add a new reply with a binary attribute type createItem(threadId, replyDateTime); // Retrieve the reply with a binary attribute type retrieveItem(threadId, replyDateTime); // clean up by deleting the item deleteItem(threadId, replyDateTime); } catch (Exception e) { System.err.println("Error running the binary attribute type example: " + e); e.printStackTrace(System.err); } } public static void createItem(String threadId, String replyDateTime) throws IOException { // Craft a long message String messageInput = "Long message to be compressed in a lengthy forum reply"; // Compress the long message ByteBuffer compressedMessage = compressString(messageInput.toString()); // Add a the reply Map<String, AttributeValue> replyInput = new HashMap<String, AttributeValue>(); replyInput.put("Id", new AttributeValue().withS(threadId)); replyInput.put("ReplyDateTime", new AttributeValue().withS(replyDateTime)); replyInput.put("Message", new AttributeValue().withS("Long message follows")); replyInput.put("ExtendedMessage", new AttributeValue().withB(compressedMessage)); replyInput.put("PostedBy", new AttributeValue().withS("User A")); PutItemRequest putReplyRequest = new PutItemRequest().withTableName(tableName).withItem(replyInput); client.putItem(putReplyRequest); } public static void retrieveItem(String threadId, String replyDateTime) throws IOException { HashMap<String, AttributeValue> key = new HashMap<String, AttributeValue>(); key.put("Id", new AttributeValue().withS(threadId)); key.put("ReplyDateTime", new AttributeValue().withS(replyDateTime)); GetItemRequest getReplyRequest = new GetItemRequest().withTableName(tableName).withKey(key) .withConsistentRead(true); GetItemResult getReplyResult = client.getItem(getReplyRequest); // Decompress the reply message and print Map<String, AttributeValue> reply = getReplyResult.getItem(); String message = decompressString(reply.get("ExtendedMessage").getB()); System.out.println("Reply message:\n" + " Id: " + reply.get("Id").getS() + "\n" + " ReplyDateTime: " + reply.get("ReplyDateTime").getS() + "\n" + " PostedBy: " + reply.get("PostedBy").getS() + "\n" + " Message: " + reply.get("Message").getS() + "\n" + " ExtendedMessage (decompressed): " + message); } public static void deleteItem(String threadId, String replyDateTime) { HashMap<String, AttributeValue> key = new HashMap<String, AttributeValue>(); key.put("Id", new AttributeValue().withS(threadId)); key.put("ReplyDateTime", new AttributeValue().withS(replyDateTime)); DeleteItemRequest deleteReplyRequest = new DeleteItemRequest().withTableName(tableName).withKey(key); client.deleteItem(deleteReplyRequest); } private static ByteBuffer compressString(String input) throws IOException { // Compress the UTF-8 encoded String into a byte[] ByteArrayOutputStream baos = new ByteArrayOutputStream(); GZIPOutputStream os = new GZIPOutputStream(baos); os.write(input.getBytes("UTF-8")); os.finish(); byte[] compressedBytes = baos.toByteArray(); // The following code writes the compressed bytes to a ByteBuffer. // A simpler way to do this is by simply calling // ByteBuffer.wrap(compressedBytes); // However, the longer form below shows the importance of resetting the // position of the buffer // back to the beginning of the buffer if you are writing bytes directly // to it, since the SDK // will consider only the bytes after the current position when sending // data to DynamoDB. // Using the "wrap" method automatically resets the position to zero. ByteBuffer buffer = ByteBuffer.allocate(compressedBytes.length); buffer.put(compressedBytes, 0, compressedBytes.length); buffer.position(0); // Important: reset the position of the ByteBuffer // to the beginning return buffer; } private static String decompressString(ByteBuffer input) throws IOException { byte[] bytes = input.array(); ByteArrayInputStream bais = new ByteArrayInputStream(bytes); ByteArrayOutputStream baos = new ByteArrayOutputStream(); GZIPInputStream is = new GZIPInputStream(bais); int chunkSize = 1024; byte[] buffer = new byte[chunkSize]; int length = 0; while ((length = is.read(buffer, 0, chunkSize)) != -1) { baos.write(buffer, 0, length); } return new String(baos.toByteArray(), "UTF-8"); } }

Sample Details

Service: dynamodb

Last tested:

Author: AWS

Type: full-example