Meta-annotations
Sometimes you may want to use the same configuration for multiple listeners. To reduce the boilerplate configuration, you can use meta-annotations to create your own listener annotation. The following example shows how to do so:
@Target({ElementType.TYPE, ElementType.METHOD, ElementType.ANNOTATION_TYPE})
@Retention(RetentionPolicy.RUNTIME)
@RabbitListener(bindings = @QueueBinding(
value = @Queue,
exchange = @Exchange(value = "metaFanout", type = ExchangeTypes.FANOUT)))
public @interface MyAnonFanoutListener {
}
public class MetaListener {
@MyAnonFanoutListener
public void handle1(String foo) {
...
}
@MyAnonFanoutListener
public void handle2(String foo) {
...
}
}
In the preceding example, each listener created by the @MyAnonFanoutListener
annotation binds an anonymous, auto-delete
queue to the fanout exchange, metaFanout
.
Starting with version 2.2.3, @AliasFor
is supported to allow overriding properties on the meta-annotated annotation.
Also, user annotations can now be @Repeatable
, allowing multiple containers to be created for a method.
@Component
static class MetaAnnotationTestBean {
@MyListener("queue1")
@MyListener("queue2")
public void handleIt(String body) {
}
}
@RabbitListener
@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
@Repeatable(MyListeners.class)
static @interface MyListener {
@AliasFor(annotation = RabbitListener.class, attribute = "queues")
String[] value() default {};
}
@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
static @interface MyListeners {
MyListener[] value();
}