CODEWITHSUNDEEP
javaspringjavabeans
kk1957
kk1957

Reputation: 8824

java listen to ContextRefreshedEvent

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 ?

Upvotes: 20

Views: 33921

Answers (4)

Chandrika Deb
Chandrika Deb

Reputation: 111

(ContextRefreshedEvent event) gets called twice, one in init and secondly after init.

You can use (ApplicationReadyEvent event) and call will be made only once after init.

public class InvokeCatalogOne implements IInvokeCatalogOne {

    @EventListener
    public void fetchChargeCode(ApplicationReadyEvent event) {

    }
}

Upvotes: 3

Manish
Manish

Reputation: 1775

I will prefer ApplicationReadyEvent. I found ContextRefreshedEvent is called before my http server is started. ApplicationReadyEvent will make sure your application is ready to take request.

    @EventListener(ApplicationReadyEvent.class)
    public void startApp() {
        LOGGER.info("Application is now ready!");
    }

Upvotes: 2

Sotirios Delimanolis
Sotirios Delimanolis

Reputation: 279990

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 class X 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.X"></bean>

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

Later Spring version support annotation-based event listeners. The documentation states

As of Spring 4.2, you can register an event listener on any public method of a managed bean by using the @EventListener annotation.

Within the X class above, you could declare an annotated method like

@EventListener
public void onEventWithArg(ContextRefreshedEvent event) {
}

or even

@EventListener(ContextRefreshedEvent.class)
public void onEventWithout() {

}

The context will detect this method and register it as a listener for the specified event type.

The documentation goes into way more detail about the full feature set: conditional processing with SpEL expression, async listeners, etc.

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.

Upvotes: 30

Radouane ROUFID
Radouane ROUFID

Reputation: 10813

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.

Upvotes: 15

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