a mix of different types of interceptors at the method level is allowed or not?

[Himai Minh]

From JSR 318 and Interceptor 1.1 documents, I do not see these documents specify that EJB containers allow a mix of lifecycle callback and method level business method interceptors. For example,

@Interceptor
public class MyLifeCycleInterceptor{
       
@PostConstruct
public void lifecycleIncMethod(){...}

}

@Interceptor
public class AroundInvInterceptor{

@AroundInvoke
public Object AIIncMethod(InvocationConext ic ){
               //do something here....
             return ic.proceed();
}

}

@Interceptors ( MyLifeCycleInterceptor.class)
public class MyApp{

//The specifications do not say having these two types of interceptor here are not allowed.
@Interceptor(AroundInvInterceptor.class)
@PostConstruct

public void myInitMethod(){....}
}

Question: Are both AroundInvInteceptor and MyLifeCycleInterceptor allowed to intercept myInitMethod() ?
The specifications do not say this is not allowed. Does it mean it is up to the EJB containers to decide if it is allowed or not?

[Frits Walraven]

The specifications do not say this is not allowed. Does it mean it is up to the EJB containers to decide if it is allowed or not?

The specification does specify how to intercept a PostConstruct method, so I would be surprised if the AroundInvoke interceptor would work here. The logical way to implement this is to ignore the AroundInvoke interceptor.

[Himai Minh]

According to Interceptor 1.1 specification, p.11

If an interceptor class that is only used as a method level interceptor defines lifecycle callback interceptor methods, those lifecycle callback interceptor method are not invoked.

This specification is talking about one interceptor class having two different types of interceptor methods (around-invoke and lifecycle interceptors).

I came up with an example of an interceptor class:

@Interceptor
public class MyInterceptor{

  @PostConstruct
  public void pcInt(){
              ...
  }

   @AroundInvoke
  public Object aiInt(InvocationContext ic) throws Exception{ 
             //do something here...
         return ic.proceed();
     }
}

 public class MyApp{

        @Interceptor (MyIntercetpor.class)
        public void myMethod(){

                     .....
       }
}

The @PostConstruct method of MyInterceptor won't be invoked as MyInterceptor is used as a method level interceptor.

However, in my previous example, there are two different interceptors, MyLifeCycleInterceptor and AroundInvokeInterceptor. The specification does not say the case when two different types of interceptors trying to intercept a method.

[Frits Walraven]

What I was trying to say is that the specifications specify how to intercept a lifecycle callback event (e.g. PostConstruct, PreDestroy). That is with a @PostConstruct or @PreDestroy annotated method inside an Interceptor class.

My interpretation of this is that is no other way to intercept such a method and therefore the @AroundInvoke interceptor on top of a a lifecycle callback event would likely to be ignored.

[Himai Minh]

Regarding to a mix of interceptor, I can demo this using Ivan's example in his chapter 6.

//This is created on my own
package com.ivan.scbcd6;
import javax.interceptor.AroundInvoke;
import javax.interceptor.Interceptor;
import javax.interceptor.InvocationContext; 

@Interceptor
public class MyAroundInvokeInterceptor {
    @AroundInvoke
    public Object logMethodEntryExit(InvocationContext inInvocationContext)throws Exception{
 	   System.out.println(" MyAroundInvoke - entering method: "+ inInvocationContext.getMethod().getName());
        Object theResult = inInvocationContext.proceed();
        System.out.println("MyAroundInvoke- exiting method: "+ inInvocationContext.getMethod().getName());
        return theResult;
 }
}

package com.ivan.scbcd6;

 ....
@LocalBean
@Interceptors(LogInterceptor.class)
public class SingletonSessionBeanA {
    private final static String BEAN_NAME="SingletonSessionBeanA";
    private String mStoredMessage = "[no message set]";
   
    @PostConstruct
    //This is ignored.
    @Interceptors(MyAroundInvokeInterceptor.class)
    public void initialize(){
    	 System.out.println("*** "+ BEAN_NAME+ " - initialized");
    }
    
   .....
    
    @Interceptors(MyAroundInvokeInterceptor.class)
    public String retrieveMessage(){
    	Date theCurrentTime = new Date();
    	String message= "Message from "+BEAN_NAME+"-"+mStoredMessage + " "+theCurrentTime;
        System.out.println("*** retrieve message :"+ message);
    	return message;
    }
    

The result is:
1. The initialize() method is only intercepted by the @PostContruct method defined in LogInterceptor, but the @AroundInvoke method of the MyAroundInvokeInterceptor is ignored.
2. retrieveMessage() method is intercepted by the @AroundInvoke of MyAroundInvokeInterceptor.
Here is the output from the console:

LogInterceptor - constructor
Info: MyDefaultInterceptor.postContruct
Info: *** SingletonSessionBeanA - initialized
Info: MyDefaultInterceptor intercepting : SingletonSessionBeanA. retrieveMessage
Info: LogInterceptorSuperclass intercepting SingletonSessionBeanA.retrieveMessage
Info: LogInterceptor - entering method: retrieveMessage
Info: MyAroundInvoke - entering method: retrieveMessage
Info: *** retrieve message :Message from SingletonSessionBeanA-[no message set] Wed Mar 11 18:09:34 EDT 2015
Info: MyAroundInvoke- exiting method: retrieveMessage
Info: LogInterceptor- exiting method: retrieveMessage