AWS Lambda：Java：Kinesis事件

Question

我无法找到我想做的事的例子...

我想在Java中创建Lambda函数。我以为我总是将Javascript用于Lambda函数，但是在这种情况下，我最终将重用已经用Java编写的应用程序逻辑，因此这很有意义。

过去，我写过由Kinesis事件触发的Javascript Lambda函数。超级简单，函数接收事件作为参数，做点什么，瞧。我想用Java做同样的事情。真的很简单：

Kinesis事件->触发函数->（Java）接收Kinesis事件，并对其进行处理

任何人都有这种用例的经验吗？

Answer 1

这是我编写的一些示例代码，用于在内部演示相同的概念。此代码将事件从一个流转发到另一个。

请注意，如果转发中有错误，此代码将不处理重试，也不意味着在生产环境中具有出色的性能，但是它确实演示了如何处理发布流中的记录。

import com.amazonaws.regions.Region;
import com.amazonaws.regions.Regions;
import com.amazonaws.services.kinesis.AmazonKinesisClient;
import com.amazonaws.services.kinesis.model.PutRecordsRequest;
import com.amazonaws.services.kinesis.model.PutRecordsRequestEntry;
import com.amazonaws.services.kinesis.model.PutRecordsResult;
import com.amazonaws.services.lambda.runtime.Context;
import com.amazonaws.services.lambda.runtime.LambdaLogger;
import com.amazonaws.services.lambda.runtime.events.KinesisEvent;

import java.nio.ByteBuffer;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.stream.Collectors;

public class KinesisToKinesis {

    private LambdaLogger logger;
    final private AmazonKinesisClient kinesisClient = new AmazonKinesisClient();

    public PutRecordsResult eventHandler(KinesisEvent event, Context context) {
        logger = context.getLogger();
        if (event == null || event.getRecords() == null) {
            logger.log("Event contains no data" + System.lineSeparator());
            return null;
        } else {
            logger.log("Received " + event.getRecords().size() +
                " records from " + event.getRecords().get(0).getEventSourceARN() + System.lineSeparator());
        }

        final Long startTime = System.currentTimeMillis();

        // set up the client
        Region region;
        final Map<String, String> environmentVariables = System.getenv();
        if (environmentVariables.containsKey("AWS_REGION")) {
            region = Region.getRegion(Regions.fromName(environmentVariables.get("AWS_REGION")));
        } else {
            region = Region.getRegion(Regions.US_WEST_2);
            logger.log("Using default region: " + region.toString() + System.lineSeparator());
        }
        kinesisClient.setRegion(region);

        Long elapsed = System.currentTimeMillis() - startTime;
        logger.log("Finished setup in " + elapsed + " ms" + System.lineSeparator());

        PutRecordsRequest putRecordsRequest = new PutRecordsRequest().withStreamName("usagecounters-global");
        List<PutRecordsRequestEntry> putRecordsRequestEntryList = event.getRecords().parallelStream()
            .map(r -> new PutRecordsRequestEntry()
                    .withData(ByteBuffer.wrap(r.getKinesis().getData().array()))
                    .withPartitionKey(r.getKinesis().getPartitionKey()))
            .collect(Collectors.toList());

        putRecordsRequest.setRecords(putRecordsRequestEntryList);

        elapsed = System.currentTimeMillis() - startTime;
        logger.log("Processed " + putRecordsRequest.getRecords().size() +
            " records in " + elapsed + " ms" + System.lineSeparator());

        PutRecordsResult putRecordsResult = kinesisClient.putRecords(putRecordsRequest);
        elapsed = System.currentTimeMillis() - startTime;
        logger.log("Forwarded " + putRecordsRequest.getRecords().size() +
                " records to Kinesis " + putRecordsRequest.getStreamName() +
                " in " + elapsed + " ms" + System.lineSeparator());
        return putRecordsResult;
    }
}