MessageResource.java 文件源码

@GET
@Timed
public Response consume(
        @QueryParam("topic") String topic,
        @QueryParam("timeout") Integer timeout
) {
    if (Strings.isNullOrEmpty(topic))
        return Response.status(400)
                .entity(new String[]{"Undefined topic"})
                .build();

    Properties props = (Properties) consumerCfg.clone();
    if (timeout != null) props.put("consumer.timeout.ms", "" + timeout);

    ConsumerConfig config = new ConsumerConfig(props);
    ConsumerConnector connector = Consumer.createJavaConsumerConnector(config);

    Map<String, Integer> streamCounts = Collections.singletonMap(topic, 1);
    Map<String, List<KafkaStream<byte[], byte[]>>> streams = connector.createMessageStreams(streamCounts);
    KafkaStream<byte[], byte[]> stream = streams.get(topic).get(0);

    List<Message> messages = new ArrayList<>();
    try {
        for (MessageAndMetadata<byte[], byte[]> messageAndMetadata : stream)
            messages.add(new Message(messageAndMetadata));
    } catch (ConsumerTimeoutException ignore) {
    } finally {
        connector.commitOffsets();
        connector.shutdown();
    }

    return Response.ok(messages).build();
}