How can i extend spring-kafka's '@KafkaListener' annotation to create my own annotation with limited attributes?

Question

I've been using '@KafkaListener' at method level to create consumers. Now, I'm trying to create my own custom annotation by extending '@KafkaListener' and limit the no of attributes (for example, because of some reasons, I don't want to expose attributes like 'errorHandler' 'containerGroup' etc ). Now my question is, to implement this, is there any option to extend the existing '@KafkaListener' ? Please suggest.

Answer 1

Yes, it's quite easy.

@SpringBootApplication
public class So61684460Application {

    public static void main(String[] args) {
        SpringApplication.run(So61684460Application.class, args);
    }

    @MyListener(topics = "so61684460", id = "so61684460")
    public void listen(String in) {
        System.out.println(in);
    }

    @Bean
    public NewTopic topic() {
        return TopicBuilder.name("so61684460").partitions(3).replicas(1).build();
    }

}

@Retention(RetentionPolicy.RUNTIME)
@Target({ ElementType.TYPE, ElementType.METHOD, ElementType.ANNOTATION_TYPE })
@KafkaListener(concurrency = "${my.concurrency}")
@interface MyListener {

    @AliasFor(annotation = KafkaListener.class, attribute = "id")
    String id();

    @AliasFor(annotation = KafkaListener.class, attribute = "topics")
    String[] topics() default "";

}

As you can see, as well as restricting the visibility of some attributes, you can make them required (id above), change the default value, or set hard-coded or parameterized values in the invisible attributes (concurrency above).

This is described in the documentation.