完成程序：DynamoDB Streams Kinesis Adapter

下文是执行 演练：DynamoDB Streams Kinesis Adapter 所述任务的完整 Java 程序。当您运行该程序时，将显示与以下内容类似的输出。

Creating table KCL-Demo-src
Creating table KCL-Demo-dest
Table is active.
Creating worker for stream: arn:aws:dynamodb:us-west-2:111122223333:table/KCL-Demo-src/stream/2015-05-19T22:48:56.601
Starting worker...
Scan result is equal.
Done.

源代码包括四个 .java 文件：

StreamsAdapterDemo.java

package com.amazonaws.codesamples;

import com.amazonaws.auth.AWSCredentialsProvider;
import com.amazonaws.auth.DefaultAWSCredentialsProviderChain;
import com.amazonaws.regions.Regions;
import com.amazonaws.services.cloudwatch.AmazonCloudWatch;
import com.amazonaws.services.cloudwatch.AmazonCloudWatchClientBuilder;
import com.amazonaws.services.dynamodbv2.AmazonDynamoDB;
import com.amazonaws.services.dynamodbv2.AmazonDynamoDBClientBuilder;
import com.amazonaws.services.dynamodbv2.AmazonDynamoDBStreams;
import com.amazonaws.services.dynamodbv2.AmazonDynamoDBStreamsClientBuilder;
import com.amazonaws.services.dynamodbv2.model.DeleteTableRequest;
import com.amazonaws.services.dynamodbv2.model.DescribeTableResult;
import com.amazonaws.services.dynamodbv2.streamsadapter.AmazonDynamoDBStreamsAdapterClient;
import com.amazonaws.services.dynamodbv2.streamsadapter.StreamsWorkerFactory;
import com.amazonaws.services.kinesis.clientlibrary.interfaces.v2.IRecordProcessorFactory;
import com.amazonaws.services.kinesis.clientlibrary.lib.worker.InitialPositionInStream;
import com.amazonaws.services.kinesis.clientlibrary.lib.worker.KinesisClientLibConfiguration;
import com.amazonaws.services.kinesis.clientlibrary.lib.worker.Worker;

public class StreamsAdapterDemo {
    private static Worker worker;
    private static KinesisClientLibConfiguration workerConfig;
    private static IRecordProcessorFactory recordProcessorFactory;

    private static AmazonDynamoDB dynamoDBClient;
    private static AmazonCloudWatch cloudWatchClient;
    private static AmazonDynamoDBStreams dynamoDBStreamsClient;
    private static AmazonDynamoDBStreamsAdapterClient adapterClient;

    private static String tablePrefix = "KCL-Demo";
    private static String streamArn;

    private static Regions awsRegion = Regions.US_EAST_2;

    private static AWSCredentialsProvider awsCredentialsProvider = DefaultAWSCredentialsProviderChain.getInstance();

    /**
     * @param args
     */
    public static void main(String[] args) throws Exception {
        System.out.println("Starting demo...");

        dynamoDBClient = AmazonDynamoDBClientBuilder.standard()
                .withRegion(awsRegion)
                .build();
        cloudWatchClient = AmazonCloudWatchClientBuilder.standard()
                .withRegion(awsRegion)
                .build();
        dynamoDBStreamsClient = AmazonDynamoDBStreamsClientBuilder.standard()
                .withRegion(awsRegion)
                .build();
        adapterClient = new AmazonDynamoDBStreamsAdapterClient(dynamoDBStreamsClient);
        String srcTable = tablePrefix + "-src";
        String destTable = tablePrefix + "-dest";
        recordProcessorFactory = new StreamsRecordProcessorFactory(dynamoDBClient, destTable);

        setUpTables();

        workerConfig = new KinesisClientLibConfiguration("streams-adapter-demo",
                streamArn,
                awsCredentialsProvider,
                "streams-demo-worker")
                .withMaxRecords(1000)
                .withIdleTimeBetweenReadsInMillis(500)
                .withInitialPositionInStream(InitialPositionInStream.TRIM_HORIZON);

        System.out.println("Creating worker for stream: " + streamArn);
        worker = StreamsWorkerFactory.createDynamoDbStreamsWorker(recordProcessorFactory, workerConfig, adapterClient,
                dynamoDBClient, cloudWatchClient);
        System.out.println("Starting worker...");
        Thread t = new Thread(worker);
        t.start();

        Thread.sleep(25000);
        worker.shutdown();
        t.join();

        if (StreamsAdapterDemoHelper.scanTable(dynamoDBClient, srcTable).getItems()
                .equals(StreamsAdapterDemoHelper.scanTable(dynamoDBClient, destTable).getItems())) {
            System.out.println("Scan result is equal.");
        } else {
            System.out.println("Tables are different!");
        }

        System.out.println("Done.");
        cleanupAndExit(0);
    }

    private static void setUpTables() {
        String srcTable = tablePrefix + "-src";
        String destTable = tablePrefix + "-dest";
        streamArn = StreamsAdapterDemoHelper.createTable(dynamoDBClient, srcTable);
        StreamsAdapterDemoHelper.createTable(dynamoDBClient, destTable);

        awaitTableCreation(srcTable);

        performOps(srcTable);
    }

    private static void awaitTableCreation(String tableName) {
        Integer retries = 0;
        Boolean created = false;
        while (!created && retries < 100) {
            DescribeTableResult result = StreamsAdapterDemoHelper.describeTable(dynamoDBClient, tableName);
            created = result.getTable().getTableStatus().equals("ACTIVE");
            if (created) {
                System.out.println("Table is active.");
                return;
            } else {
                retries++;
                try {
                    Thread.sleep(1000);
                } catch (InterruptedException e) {
                    // do nothing
                }
            }
        }
        System.out.println("Timeout after table creation. Exiting...");
        cleanupAndExit(1);
    }

    private static void performOps(String tableName) {
        StreamsAdapterDemoHelper.putItem(dynamoDBClient, tableName, "101", "test1");
        StreamsAdapterDemoHelper.updateItem(dynamoDBClient, tableName, "101", "test2");
        StreamsAdapterDemoHelper.deleteItem(dynamoDBClient, tableName, "101");
        StreamsAdapterDemoHelper.putItem(dynamoDBClient, tableName, "102", "demo3");
        StreamsAdapterDemoHelper.updateItem(dynamoDBClient, tableName, "102", "demo4");
        StreamsAdapterDemoHelper.deleteItem(dynamoDBClient, tableName, "102");
    }

    private static void cleanupAndExit(Integer returnValue) {
        String srcTable = tablePrefix + "-src";
        String destTable = tablePrefix + "-dest";
        dynamoDBClient.deleteTable(new DeleteTableRequest().withTableName(srcTable));
        dynamoDBClient.deleteTable(new DeleteTableRequest().withTableName(destTable));
        System.exit(returnValue);
    }
}

StreamsRecordProcessor.java

package com.amazonaws.codesamples;

import com.amazonaws.services.dynamodbv2.AmazonDynamoDB;
import com.amazonaws.services.dynamodbv2.streamsadapter.model.RecordAdapter;
import com.amazonaws.services.kinesis.clientlibrary.interfaces.v2.IRecordProcessor;
import com.amazonaws.services.kinesis.clientlibrary.lib.worker.ShutdownReason;
import com.amazonaws.services.kinesis.clientlibrary.types.InitializationInput;
import com.amazonaws.services.kinesis.clientlibrary.types.ProcessRecordsInput;
import com.amazonaws.services.kinesis.clientlibrary.types.ShutdownInput;
import com.amazonaws.services.kinesis.model.Record;

import java.nio.charset.Charset;

public class StreamsRecordProcessor implements IRecordProcessor {
    private Integer checkpointCounter;

    private final AmazonDynamoDB dynamoDBClient;
    private final String tableName;

    public StreamsRecordProcessor(AmazonDynamoDB dynamoDBClient2, String tableName) {
        this.dynamoDBClient = dynamoDBClient2;
        this.tableName = tableName;
    }

    @Override
    public void initialize(InitializationInput initializationInput) {
        checkpointCounter = 0;
    }

    @Override
    public void processRecords(ProcessRecordsInput processRecordsInput) {
        for (Record record : processRecordsInput.getRecords()) {
            String data = new String(record.getData().array(), Charset.forName("UTF-8"));
            System.out.println(data);
            if (record instanceof RecordAdapter) {
                com.amazonaws.services.dynamodbv2.model.Record streamRecord = ((RecordAdapter) record)
                        .getInternalObject();

                switch (streamRecord.getEventName()) {
                    case "INSERT":
                    case "MODIFY":
                        StreamsAdapterDemoHelper.putItem(dynamoDBClient, tableName,
                                streamRecord.getDynamodb().getNewImage());
                        break;
                    case "REMOVE":
                        StreamsAdapterDemoHelper.deleteItem(dynamoDBClient, tableName,
                                streamRecord.getDynamodb().getKeys().get("Id").getN());
                }
            }
            checkpointCounter += 1;
            if (checkpointCounter % 10 == 0) {
                try {
                    processRecordsInput.getCheckpointer().checkpoint();
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        }

    }

    @Override
    public void shutdown(ShutdownInput shutdownInput) {
        if (shutdownInput.getShutdownReason() == ShutdownReason.TERMINATE) {
            try {
                shutdownInput.getCheckpointer().checkpoint();
            } catch (Exception e) {
                e.printStackTrace();
            }
        }

    }
}

StreamsRecordProcessorFactory.java

package com.amazonaws.codesamples;

import com.amazonaws.services.dynamodbv2.AmazonDynamoDB;
import com.amazonaws.services.kinesis.clientlibrary.interfaces.v2.IRecordProcessor;
import com.amazonaws.services.kinesis.clientlibrary.interfaces.v2.IRecordProcessorFactory;

public class StreamsRecordProcessorFactory implements IRecordProcessorFactory {
    private final String tableName;
    private final AmazonDynamoDB dynamoDBClient;

    public StreamsRecordProcessorFactory(AmazonDynamoDB dynamoDBClient, String tableName) {
        this.tableName = tableName;
        this.dynamoDBClient = dynamoDBClient;
    }

    @Override
    public IRecordProcessor createProcessor() {
        return new StreamsRecordProcessor(dynamoDBClient, tableName);
    }
}

StreamsAdapterDemoHelper.java

package com.amazonaws.codesamples;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.Map;

import com.amazonaws.services.dynamodbv2.AmazonDynamoDB;
import com.amazonaws.services.dynamodbv2.model.AttributeAction;
import com.amazonaws.services.dynamodbv2.model.AttributeDefinition;
import com.amazonaws.services.dynamodbv2.model.AttributeValue;
import com.amazonaws.services.dynamodbv2.model.AttributeValueUpdate;
import com.amazonaws.services.dynamodbv2.model.CreateTableRequest;
import com.amazonaws.services.dynamodbv2.model.CreateTableResult;
import com.amazonaws.services.dynamodbv2.model.DeleteItemRequest;
import com.amazonaws.services.dynamodbv2.model.DescribeTableRequest;
import com.amazonaws.services.dynamodbv2.model.DescribeTableResult;
import com.amazonaws.services.dynamodbv2.model.KeySchemaElement;
import com.amazonaws.services.dynamodbv2.model.KeyType;
import com.amazonaws.services.dynamodbv2.model.ProvisionedThroughput;
import com.amazonaws.services.dynamodbv2.model.PutItemRequest;
import com.amazonaws.services.dynamodbv2.model.ResourceInUseException;
import com.amazonaws.services.dynamodbv2.model.ScanRequest;
import com.amazonaws.services.dynamodbv2.model.ScanResult;
import com.amazonaws.services.dynamodbv2.model.StreamSpecification;
import com.amazonaws.services.dynamodbv2.model.StreamViewType;
import com.amazonaws.services.dynamodbv2.model.UpdateItemRequest;

public class StreamsAdapterDemoHelper {

    /**
     * @return StreamArn
     */
    public static String createTable(AmazonDynamoDB client, String tableName) {
        java.util.List<AttributeDefinition> attributeDefinitions = new ArrayList<AttributeDefinition>();
        attributeDefinitions.add(new AttributeDefinition().withAttributeName("Id").withAttributeType("N"));

        java.util.List<KeySchemaElement> keySchema = new ArrayList<KeySchemaElement>();
        keySchema.add(new KeySchemaElement().withAttributeName("Id").withKeyType(KeyType.HASH)); // Partition
                                                                                                 // key

        ProvisionedThroughput provisionedThroughput = new ProvisionedThroughput().withReadCapacityUnits(2L)
                .withWriteCapacityUnits(2L);

        StreamSpecification streamSpecification = new StreamSpecification();
        streamSpecification.setStreamEnabled(true);
        streamSpecification.setStreamViewType(StreamViewType.NEW_IMAGE);
        CreateTableRequest createTableRequest = new CreateTableRequest().withTableName(tableName)
                .withAttributeDefinitions(attributeDefinitions).withKeySchema(keySchema)
                .withProvisionedThroughput(provisionedThroughput).withStreamSpecification(streamSpecification);

        try {
            System.out.println("Creating table " + tableName);
            CreateTableResult result = client.createTable(createTableRequest);
            return result.getTableDescription().getLatestStreamArn();
        } catch (ResourceInUseException e) {
            System.out.println("Table already exists.");
            return describeTable(client, tableName).getTable().getLatestStreamArn();
        }
    }

    public static DescribeTableResult describeTable(AmazonDynamoDB client, String tableName) {
        return client.describeTable(new DescribeTableRequest().withTableName(tableName));
    }

    public static ScanResult scanTable(AmazonDynamoDB dynamoDBClient, String tableName) {
        return dynamoDBClient.scan(new ScanRequest().withTableName(tableName));
    }

    public static void putItem(AmazonDynamoDB dynamoDBClient, String tableName, String id, String val) {
        java.util.Map<String, AttributeValue> item = new HashMap<String, AttributeValue>();
        item.put("Id", new AttributeValue().withN(id));
        item.put("attribute-1", new AttributeValue().withS(val));

        PutItemRequest putItemRequest = new PutItemRequest().withTableName(tableName).withItem(item);
        dynamoDBClient.putItem(putItemRequest);
    }

    public static void putItem(AmazonDynamoDB dynamoDBClient, String tableName,
            java.util.Map<String, AttributeValue> items) {
        PutItemRequest putItemRequest = new PutItemRequest().withTableName(tableName).withItem(items);
        dynamoDBClient.putItem(putItemRequest);
    }

    public static void updateItem(AmazonDynamoDB dynamoDBClient, String tableName, String id, String val) {
        java.util.Map<String, AttributeValue> key = new HashMap<String, AttributeValue>();
        key.put("Id", new AttributeValue().withN(id));

        Map<String, AttributeValueUpdate> attributeUpdates = new HashMap<String, AttributeValueUpdate>();
        AttributeValueUpdate update = new AttributeValueUpdate().withAction(AttributeAction.PUT)
                .withValue(new AttributeValue().withS(val));
        attributeUpdates.put("attribute-2", update);

        UpdateItemRequest updateItemRequest = new UpdateItemRequest().withTableName(tableName).withKey(key)
                .withAttributeUpdates(attributeUpdates);
        dynamoDBClient.updateItem(updateItemRequest);
    }

    public static void deleteItem(AmazonDynamoDB dynamoDBClient, String tableName, String id) {
        java.util.Map<String, AttributeValue> key = new HashMap<String, AttributeValue>();
        key.put("Id", new AttributeValue().withN(id));

        DeleteItemRequest deleteItemRequest = new DeleteItemRequest().withTableName(tableName).withKey(key);
        dynamoDBClient.deleteItem(deleteItemRequest);
    }

}