Java, Software Development, Spring, Spring Boot

Spring Boot – Publish and Consume Custom Application Events

This post shows how to implement the Observer Design Pattern using the facilities available from Spring Application Events. More importantly, it shows how to publish and consume custom application events in Spring Boot.

Observer Design Pattern – Publish And Consume Events

Here is a short video that describes the Observer Design Pattern

Codes To Publish And Consume Custom Events

Let us create a new Spring Boot Application using IntelliJ (optional) and Spring Initialzr. All in all, we will use these classes and interfaces from Spring Boot.

  1. org.springframework.context.ApplicationListener
  2. org.springframework.context.ApplicationEventPublisherAware
  3. org.springframework.context.ApplicationEvent

First, we create a new project. Choose Spring Initialzr. Then click Next.

Spring Boot Publish Consume Custom Application Events

Then, provide project information on the next screen.

Spring Boot Publish Consume Custom Application Events

Next, skip the screen for dependencies.

Then, save the new project to some location.

Next, we create a custom event class. This is the event type that gets published and consumed by our codes.

Then, we create an event publisher.

After that, we create an event source class.

Finally, we create an event handler. This represents our observer who handles the event. It basically waits for an event “sent” by the publisher. It is possible to have multiple observers by creating a similar class that implements the same interface.

Spring Boot Main class

When we run our codes, we get the following output showing the codes published and consumed an event in Spring Boot.

Spring Boot Publish Consume Custom Application Events

Download the Spring Boot codes

The full source codes are available on this link.

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