java如何在Spring Cloud Stream Kafka binding中编写订阅主题的方法？

Question

我想写一个消费者方法，用KafkaListener订阅一个主题

我找到了一个答案，表明了这一点-

@KafkaListener(id = "foo", topics = "dead-out")
public void dlq(Message<?> in) {
    System.out.println("DLQ:" + in);
}

现在，注释中的“主题”是订阅主题的名称。但什么是“id”字段？还是有更好的方法

谢谢你的帮助

Answer 1

@KafkaListener与春云流无关；这是ApacheKafka项目的春天（SpringCloudStream将其用于Kafka活页夹）

参见javadocs

    /**
     * The unique identifier of the container managing for this endpoint.
     * <p>If none is specified an auto-generated one is provided.
     * <p>Note: When provided, this value will override the group id property
     * in the consumer factory configuration, unless {@link #idIsGroup()}
     * is set to false.
     * <p>SpEL {@code #{...}} and property place holders {@code ${...}} are supported.
     * @return the {@code id} for the container managing for this endpoint.
     * @see org.springframework.kafka.config.KafkaListenerEndpointRegistry#getListenerContainer(String)
     */
    String id() default "";

id还用于从KafkaListenerEndpointRegistrybean获取侦听器容器，这样您就可以stop()和start()访问它

如果你想改用spring cloud stream；阅读它的文档