AspectJ: custom *.aj file is ignored

Question

Why aspectj-maven-plugin ignore my AnnotationInheritor.aj file? Am I configured something wrong?

I want to advice ItemRepository

Answer 1

I copied your code into an AspectJ project (no Spring or Spring AOP there) in order to test it. I found a few problems:

• @Around("@annotation(MyAnnotation)") will not find the annotation because there is no fully qualified class name.

• declare @method : void ItemRepository+.getById() : @MyAnnotation; does not match your interface method's signature Item getById(Long id).

• MyAspects.execute(..) needs to throw Throwable and of course also return something, such as the result of joinPoint.proceed(). But maybe that was just sloppy copy & paste.

After fixing this, the following MCVE works beautifully:

Helper classes making the project compile:

package de.scrum_master.app;

public class Item {}

package de.scrum_master.app;

public interface JpaRepository {}

package de.scrum_master.app;

import org.springframework.stereotype.Repository;

@Repository
public interface ItemRepository extends JpaRepository {
  Item getById(Long id);
}

package de.scrum_master.app;

public class ItemRepositoryImpl implements ItemRepository {
  @Override
  public Item getById(Long id) {
    return new Item();
  }
}

Marker annotation:

package de.scrum_master.app;

import java.lang.annotation.*;

@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
@Inherited
public @interface MyAnnotation {}

Driver Application:

package de.scrum_master.app;

public class Application {
  public static void main(String[] args) {
    ItemRepository repository = new ItemRepositoryImpl();
    repository.getById(11L);
  }
}

Aspects:

Just in case you wonder why I added execution(* *(..)) to the pointcut, this is because I wanted to exclude matching call() joinpoints which are available in AspectJ as opposed to Spring AOP.

package de.scrum_master.aspect;

import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.annotation.Around;
import org.aspectj.lang.annotation.Aspect;
import org.springframework.stereotype.Component;

@Aspect
@Component
public class MyAspect {
  @Around("@annotation(de.scrum_master.app.MyAnnotation) && execution(* *(..))")
  public Object execute(ProceedingJoinPoint joinPoint) throws Throwable {
    System.out.println(joinPoint);
    return joinPoint.proceed();
  }
}

package de.scrum_master.aspect;

import de.scrum_master.app.Item;
import de.scrum_master.app.ItemRepository;
import de.scrum_master.app.MyAnnotation;

public aspect AnnotationInheritor {
  declare @method : Item ItemRepository+.getById(Long) : @MyAnnotation;
}

Console log:

execution(Item de.scrum_master.app.ItemRepositoryImpl.getById(Long))

Voilà! It works nicely.

If it does not work for you like this you have other issues such as (but not exclusively)

• the "auto-generated ItemRepositoryImpl#getById" you mentioned in passing. Whenever and wherever this is generated during the build process, it needs to exist before the aspect is applied to it. In order to analyze this I would need an MCVE on GitHub, though.

• whether the target code to weave the aspect into is in the same Maven module as the aspect code. If it is not, you need to change your Maven setup.