Close

Spring - Transforming events

[Last Updated: Jun 11, 2021]

In Spring, events can be transformed from one type to another.

We can use an non-void return type with the listener methods (methods annotated with @EventListener). We will do that if we want to publish another event at the end of processing current event.

Example

package com.logicbig.example;

import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.event.EventListener;

@Configuration
public class EventTransformingExample {
    @Bean
    AListenerBean listenerBean() {
        return new AListenerBean();
    }

    @Bean
    AnotherListenerBean anotherListenerBean() {
        return new AnotherListenerBean();
    }

    public static void main(String[] args) {
        AnnotationConfigApplicationContext context =
                new AnnotationConfigApplicationContext(EventTransformingExample.class);
        context.publishEvent(new MyEvent("test message 1"));
    }

    private static class AListenerBean {
        @EventListener
        public MyAnotherEvent handleContextEvent(MyEvent myEvent) {
            System.out.printf("event received by %s, event: %s%n", this.getClass().getSimpleName(), myEvent);
            return new MyAnotherEvent("test message 2");
        }
    }

    private static class AnotherListenerBean {
        @EventListener
        public void handleContextEvent(MyAnotherEvent myEvent) {
            System.out.printf("event received by %s, event: %s%n", this.getClass().getSimpleName(), myEvent);
        }
    }

    private static class MyEvent {
        private String msg;

        public MyEvent(String msg) {
            this.msg = msg;
        }

        @Override
        public String toString() {
            return "MyEvent{" +
                    "msg='" + msg + '\'' +
                    '}';
        }
    }

    private static class MyAnotherEvent {
        private String msg;

        public MyAnotherEvent(String msg) {
            this.msg = msg;
        }

        @Override
        public String toString() {
            return "MyAnotherEvent{" +
                    "msg='" + msg + '\'' +
                    '}';
        }
    }
}

Output

event received by AListenerBean, event: MyEvent{msg='test message 1'}
event received by AnotherListenerBean, event: MyAnotherEvent{msg='test message 2'}

Example Project

Dependencies and Technologies Used:

  • spring-context 5.3.8: Spring Context. Version Compatibility: 4.2.0.RELEASE - 5.3.8 Version List
    ×

    Version compatibilities of spring-context with this example:

    • 4.2.0.RELEASE
    • 4.2.1.RELEASE
    • 4.2.2.RELEASE
    • 4.2.3.RELEASE
    • 4.2.4.RELEASE
    • 4.2.5.RELEASE
    • 4.2.6.RELEASE
    • 4.2.7.RELEASE
    • 4.2.8.RELEASE
    • 4.2.9.RELEASE
    • 4.3.0.RELEASE
    • 4.3.1.RELEASE
    • 4.3.2.RELEASE
    • 4.3.3.RELEASE
    • 4.3.4.RELEASE
    • 4.3.5.RELEASE
    • 4.3.6.RELEASE
    • 4.3.7.RELEASE
    • 4.3.8.RELEASE
    • 4.3.9.RELEASE
    • 4.3.10.RELEASE
    • 4.3.11.RELEASE
    • 4.3.12.RELEASE
    • 4.3.13.RELEASE
    • 4.3.14.RELEASE
    • 4.3.15.RELEASE
    • 4.3.16.RELEASE
    • 4.3.17.RELEASE
    • 4.3.18.RELEASE
    • 4.3.19.RELEASE
    • 4.3.20.RELEASE
    • 4.3.21.RELEASE
    • 4.3.22.RELEASE
    • 4.3.23.RELEASE
    • 4.3.24.RELEASE
    • 4.3.25.RELEASE
    • 4.3.26.RELEASE
    • 4.3.27.RELEASE
    • 4.3.28.RELEASE
    • 4.3.29.RELEASE
    • 4.3.30.RELEASE
    • 5.0.0.RELEASE
    • 5.0.1.RELEASE
    • 5.0.2.RELEASE
    • 5.0.3.RELEASE
    • 5.0.4.RELEASE
    • 5.0.5.RELEASE
    • 5.0.6.RELEASE
    • 5.0.7.RELEASE
    • 5.0.8.RELEASE
    • 5.0.9.RELEASE
    • 5.0.10.RELEASE
    • 5.0.11.RELEASE
    • 5.0.12.RELEASE
    • 5.0.13.RELEASE
    • 5.0.14.RELEASE
    • 5.0.15.RELEASE
    • 5.0.16.RELEASE
    • 5.0.17.RELEASE
    • 5.0.18.RELEASE
    • 5.0.19.RELEASE
    • 5.0.20.RELEASE
    • 5.1.0.RELEASE
    • 5.1.1.RELEASE
    • 5.1.2.RELEASE
    • 5.1.3.RELEASE
    • 5.1.4.RELEASE
    • 5.1.5.RELEASE
    • 5.1.6.RELEASE
    • 5.1.7.RELEASE
    • 5.1.8.RELEASE
    • 5.1.9.RELEASE
    • 5.1.10.RELEASE
    • 5.1.11.RELEASE
    • 5.1.12.RELEASE
    • 5.1.13.RELEASE
    • 5.1.14.RELEASE
    • 5.1.15.RELEASE
    • 5.1.16.RELEASE
    • 5.1.17.RELEASE
    • 5.1.18.RELEASE
    • 5.1.19.RELEASE
    • 5.1.20.RELEASE
    • 5.2.0.RELEASE
    • 5.2.1.RELEASE
    • 5.2.2.RELEASE
    • 5.2.3.RELEASE
    • 5.2.4.RELEASE
    • 5.2.5.RELEASE
    • 5.2.6.RELEASE
    • 5.2.7.RELEASE
    • 5.2.8.RELEASE
    • 5.2.9.RELEASE
    • 5.2.10.RELEASE
    • 5.2.11.RELEASE
    • 5.2.12.RELEASE
    • 5.2.13.RELEASE
    • 5.2.14.RELEASE
    • 5.2.15.RELEASE
    • 5.3.0
    • 5.3.1
    • 5.3.2
    • 5.3.3
    • 5.3.4
    • 5.3.5
    • 5.3.6
    • 5.3.7
    • 5.3.8

    Versions in green have been tested.

  • JDK 8
  • Maven 3.8.1

Spring - Transforming to other events Select All Download
  • spring-transforming-to-other-events
    • src
      • main
        • java
          • com
            • logicbig
              • example
                • EventTransformingExample.java

    See Also