Question on Message-Driven Bean Lifecycle Callback Interceptor Methods

[Mohit G Gupta]

EJB 3.1 Specification

5.4.5 Message-Driven Bean Lifecycle Callback Interceptor Methods

The following lifecycle event callbacks are supported for message-driven beans. Callback methods may be defined directly on the bean class or on a separate interceptor class

1. PostConstruct
2. PreDestroy

Question :What does line "Callback methods may be defined directly on the bean class or on a separate interceptor class" means here ?

[Frits Walraven]

You can have an interceptor binding on top of the PostConstruct method, or in the Interceptor class itself

Method signature:

In Target class: void <METHOD>()

In Interceptor class void <METHOD>(InvocationContext)

in Target class

@Interceptors({PrincipalLogger.class}) 
@PostConstruct
private void init(){
     System.out.println("PostConstruct);
} 

in Interceptor class

@Interceptor
public class MyInterceptor {
   @PostConstruct
   public void someMethod(InvocationContext ctx) {
      System.out.println("@PostConstruct interceptor");
      ctx.proceed();
   }
}

... and the target clas ....

@Interceptors({MyInterceptor.class})
@Stateless 
public class EchoBean implements EchoBeanRemote {
   @PostConstruct void initBean() { ... }
}

Regards,
Frits

[Mohit G Gupta]

Hi Frits,

Thanks for the reply.
However,I am still not understanding your statement as my query was regarding "callback methods (PostConstruct,PreDestroy) defined on Bean class or Interceptor class" and your answers says about" Interceptor Bindings on PostConstruct method, or in the Interceptor class itself"

Please advise.

[Frits Walraven]

Oh yes, you are right they are talking about the lifecycle methods. Well here are the examples:

in the Session bean class:

@Stateless   
public class EchoBean implements EchoBeanRemote {  
   @PostConstruct 
   void initBean() { ... }  
} 

or in the interceptor class (PostConstruct is not called from the EchoBeanRemote class but from its Interceptor)

@Interceptors({MyInterceptor.class})  
@Stateless   
public class EchoBean implements EchoBeanRemote {  
  // other methods
} 

...

@Interceptor  
public class MyInterceptor {  
   @PostConstruct  
   public void someMethod(InvocationContext ctx) {  
      System.out.println("@PostConstruct interceptor");  
      ctx.proceed();  
   }  
} 

Regards,
Frits

[Mohit G Gupta]

Thanks Frits