java listen to ContextRefreshedEvent

Question

I have a classX in my spring application in which I want to be able to find out if all spring beans have been initialized. To do this, I am trying to listen ContextRefreshedEvent.

So far I have the following code but I am not sure if this is enough.

import org.springframework.context.ApplicationListener;
import org.springframework.context.event.ContextRefreshedEvent;

public classX implements ApplicationListener<ContextRefreshedEvent> {
    @Override
    public void onApplicationEvent(ContextRefreshedEvent event) {
       //do something if all apps have initialised
    }
}

1. Is this approach correct to find out if all beans have initialsed?
2. What else do I need to do to be able to listen to the ContextRefreshedEvent ? DO I need to register classX somewhere in xml files ?

Answer 1

A ContextRefreshEvent occurs

when an ApplicationContext gets initialized or refreshed.

so you are on the right track.

What you need to do is declare a bean definition for classX.

Either with @Component and a component scan over the package it's in

@Component
public classX implements ApplicationListener<ContextRefreshedEvent> {
    @Override
    public void onApplicationEvent(ContextRefreshedEvent event) {
       //do something if all apps have initialised
    }
}

or with a <bean> declaration

<bean class="some.pack.classX"></bean>

Spring will detect that the bean is of type ApplicationListener and register it without any further configuration.

---

Just FYI, Java has naming conventions for types, variables, etc. For classes, the convention is to have their names start with an uppercase alphabetic character.

Answer 2

Spring >= 4.2

You can use annotation-driven event listener as below :

@Component
public class classX  {

    @EventListener
    public void handleContextRefresh(ContextRefreshedEvent event) {

    }
}

the ApplicationListener you want to register is defined in the signature of the method.