通用Spring Kafka监听器

Question

I have made a kafka producer and consumer in one maven project.

I want to use it in another maven project, so I added the dependency of the above kafka project. Now the problem is producer is fine but how to make listener generic that can be override by all other project which add this project.

Currently I have Listener in one project

public class Listener {
    public CountDownLatch countDownLatch0 = new CountDownLatch(3);
    public CountDownLatch countDownLatch1 = new CountDownLatch(3);
    public CountDownLatch countDownLatch2 = new CountDownLatch(3);

    @KafkaListener(id = "id0", topicPartitions = { @TopicPartition(topic = "SpringKafkaTopic1", partitions = { "0" }) })
    public void listenPartition0(ConsumerRecord<?, ?> record) {
        System.out.println("Listener Id0, Thread ID: " + Thread.currentThread().getId());
        System.out.println("Received: " + record);
        countDownLatch0.countDown();
    }

    @KafkaListener(id = "id1", topicPartitions = { @TopicPartition(topic = "SpringKafkaTopic1", partitions = { "1" }) })
    public void listenPartition1(ConsumerRecord<?, ?> record) {
        System.out.println("Listener Id1, Thread ID: " + Thread.currentThread().getId());
        System.out.println("Received: " + record);
        countDownLatch1.countDown();
    }

    @KafkaListener(id = "id2", topicPartitions = { @TopicPartition(topic = "SpringKafkaTopic1", partitions = { "2" }) })
    public void listenPartition2(ConsumerRecord<?, ?> record) {
        System.out.println("Listener Id2, Thread ID: " + Thread.currentThread().getId());
        System.out.println("Received: " + record);
        countDownLatch2.countDown();
    }

How do I make generic listener which can be overriden by all other project who all add this project as dependency and can listen to their respective topics

Answer 1

If i'm understanding your question properly, I think you'd need to do something like this:

In the shared .jar ...

public abstract class Listener {
  public CountDownLatch countDownLatch0 = new CountDownLatch(3);
  public CountDownLatch countDownLatch1 = new CountDownLatch(3);
  public CountDownLatch countDownLatch2 = new CountDownLatch(3);


  abstract void handlePartition0(record);
  abstract void handlePartition1(record);
  abstract void handlePartition2(record);

  @KafkaListener(id = "id0", topicPartitions = { @TopicPartition(topic = "SpringKafkaTopic1", partitions = { "0" }) })
  public void listenPartition0(ConsumerRecord<?, ?> record) {
    handlePartition0(record);
    countDownLatch0.countDown();
  }

  @KafkaListener(id = "id1", topicPartitions = { @TopicPartition(topic = "SpringKafkaTopic1", partitions = { "1" }) })
  public void listenPartition1(ConsumerRecord<?, ?> record) {
    handlePartition1(record);
    countDownLatch1.countDown();
  }

  @KafkaListener(id = "id2", topicPartitions = { @TopicPartition(topic = "SpringKafkaTopic1", partitions = { "2" }) })
  public void listenPartition2(ConsumerRecord<?, ?> record) {
    handlePartition2(record);
    countDownLatch2.countDown();
  }
}

Then in the child projects, import the shared .jar and import the handleXXX methods.

public class MyChildListener extends Listener {
  public void handlePartition0(Record<?,?> r) { 
    // do something useful
  }
  ...
}

This might work for you.