Inherit Annotation from Interface for pointcutting

[rdohna]

Hi!

I would like to annotate my business interfaces so I can define pointcuts for them. Something like:

@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.TYPE)
public @interface BusinessInterface {
}

@BusinessInterface
public interface MyBusinessInterface {
    public void myBusinessMethod();
}

public class MyBusinessImpl implements MyBusinessInterface {
    public void myBusinessMethod() {
        ...
    }
}

@Pointcut("@within(BusinessInterface)")
protected void businessInterface() {
}

@Around("businessInterface()")
protected Object myBusinessInterfaceCall(ProceedingJoinPoint joinPoint) throws Throwable {
    ...
}

Too bad that annotations on interfaces are not inheritable... only class annotations can!!!

Is there any way I can still define a pointcut for all implementations of an interface?!?

I think this is not such an esoteric requirement, is it?!?


Kind regards!

[bdangubic]

execution(* com.xxx.xxx.BusinessInterface+.*(..)) should do it.

[rdohna]

Hi bdangubic,

I don't understand what the "+" means, it's obviously not in the Spring doc.

But while specifying the interface directly like in ...

    @Pointcut("execution(* com.xxx.xxx.MyBusinessInterface.*(..))")

... works, simply changing it to ...

    @Pointcut("execution(* com.xxx.xxx.BusinessInterface+.*(..))")

... doesn't work ;-(

Any ideas, as to why?!?


Kind Regards

[bdangubic]

the extra + is for matching any classes that implement the interface MyBusinessInterface. not sure why it does not work for you though...

[rdohna]

If I understand you correctly, then this would work:

@Pointcut("execution(* com.xxx.xxx.MyBusinessInterface+.*(..))")

But what I want is one more indirection: MyBusinessImpl implements MyBusinessInterface which in turn is annotated as BusinessInterface, and I want my pointcut to match all implementations of all interfaces annotated to be BusinessInterfaces.

I could use a naming convention like this:

@Pointcut("execution(* com.xxx.xxx.*BusinessInterface+.*(..))")

But that would make the names of my business interfaces quite long winded. And eventually I would have to fetch the values of the annotation by hand.

[controlix]

Why don't you annotate your business classes instead of your business interfaces?

This should work:

@BusinessInterface
public class MyBusinessImpl implements MyBusinessInterface {
public void myBusinessMethod() {
...
}
}

[rdohna]

I had been thinking of that first, by I may want to have different implementations for the same interface.

[controlix]

So? You'll have to annotate all your different implementations.

[controlix]

Try this

@Pointcut("this(BusinessInterfaceMarker)")
protected void businessInterface() {}

public interface MyBusinessInterface extends BusinessInterfaceMarker {
	public void myBusinessMethod();
}

Now all method that belong to a BusinessMarkerInterface get adviced.

[rdohna]

Right now I'm annotating all implementations, but it is not as elegant as I would have liked it to be. Making the BusinessInterface not an annotation but a base interface as you suggesed works as well, but then I don't have an annotation object with values that I can access.

Nevertheless: Thanks for all the ideas... I guess there is simply no super-elegant solution (yet?).

Kind regards