Question

我无法找到我正在尝试做的事情......

我想用Java创建一个Lambda函数。我以为我总是将Javascript用于Lambda函数，但在这种情况下，我最终会重新使用已经用Java编写的应用程序逻辑，所以它是有道理的。

在过去，我编写了由Kinesis事件触发的Javascript Lambda函数。超级简单，功能接收事件作为参数，做点什么，瞧。我想用Java做同样的事情。真的很简单：

Kinesis事件 - ＆gt;触发功能 - ＆gt; （Java）接收Kinesis事件，用它们做点什么

有没有这种用例的经验？

Answer 1

以下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流。

请注意，如果转发中存在错误，此代码不会处理重试，也不意味着在生产环境中具有高效性，但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;
    }
}

AWS Lambda：Java：Kinesis Events

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