再次使用来自kafka日志压缩主题的消息

Question

我有一个带有Kafka使用者的spring应用程序，它使用@KafKalisterner注释。正在使用的主题是日志压缩的，我们可能会遇到必须再次使用主题消息的情况。以编程方式实现这一目标的最佳方法是什么？我们不控制Kafka主题配置。

Answer 1

    @KafkaListener(...)
    public void listen(String in, @Header(KafkaHeaders.CONSUMER) Consumer<?, ?> consumer) {
        System.out.println(in);
        if (this.resetNeeded) {
            consumer.seekToBeginning(consumer.assignment());
            this.resetNeeded = false;
        }
    }

如果要在侦听器空闲（没有记录）时重置，可以启用空闲事件，并通过在ApplicationListener或@eventListener方法中侦听ListenerContainerIdleEvent来执行查找。

该事件具有对使用者的引用。

编辑

@SpringBootApplication
public class So58769796Application {

    public static void main(String[] args) {
        SpringApplication.run(So58769796Application.class, args);
    }

    @KafkaListener(id = "so58769796", topics = "so58769796")
    public void listen1(String value, @Header(KafkaHeaders.RECEIVED_MESSAGE_KEY) String key) {
        System.out.println("One:" + key + ":" + value);
    }

    @KafkaListener(id = "so58769796a", topics = "so58769796")
    public void listen2(String value, @Header(KafkaHeaders.RECEIVED_MESSAGE_KEY) String key) {
        System.out.println("Two:" + key + ":" + value);
    }

    @Bean
    public NewTopic topic() {
        return TopicBuilder.name("so58769796")
                .compact()
                .partitions(1)
                .replicas(1)
                .build();
    }

    boolean reset;

    @Bean
    public ApplicationRunner runner(KafkaTemplate<String, String> template) {
        return args -> {
            template.send("so58769796", "foo", "bar");
            System.out.println("Hit enter to rewind");
            System.in.read();
            this.reset = true;
        };
    }

    @EventListener
    public void listen(ListenerContainerIdleEvent event) {
        System.out.println(event);
        if (this.reset && event.getListenerId().startsWith("so58769796-")) {
            event.getConsumer().seekToBeginning(event.getConsumer().assignment());
        }
    }

}

spring.kafka.listener.idle-event-interval=5000

这里还有另一个技巧--在这种情况下，我们每次启动应用程序时都要倒带（并按需）...

@SpringBootApplication
public class So58769796Application implements ConsumerSeekAware {

    public static void main(String[] args) {
        SpringApplication.run(So58769796Application.class, args);
    }

    @KafkaListener(id = "so58769796", topics = "so58769796")
    public void listen(String value, @Header(KafkaHeaders.RECEIVED_MESSAGE_KEY) String key) {
        System.out.println(key + ":" + value);
    }

    @Bean
    public NewTopic topic() {
        return TopicBuilder.name("so58769796")
                .compact()
                .partitions(1)
                .replicas(1)
                .build();
    }

    @Bean
    public ApplicationRunner runner(KafkaTemplate<String, String> template,
            KafkaListenerEndpointRegistry registry) {

        return args -> {
            template.send("so58769796", "foo", "bar");
            System.out.println("Hit enter to rewind");
            System.in.read();
            registry.getListenerContainer("so58769796").stop();
            registry.getListenerContainer("so58769796").start();
        };

    }

    @Override
    public void onPartitionsAssigned(Map<TopicPartition, Long> assignments, ConsumerSeekCallback callback) {
        assignments.keySet().forEach(tp -> callback.seekToBeginning(tp.topic(), tp.partition()));
    }

}