Why is it expected ")" if i don't add "+" when programming with Aspectj annotations

Question

package org.example;

@Aspect
@Order(value = 2)
@Component
public class SayAspect {
    @DeclareParents(value = "org.example..*+", defaultImpl = DefaultGoodBye.class)
    private GoodBye goodBye;
    private int count = 0;
}

I want to add an import for all classes in the org.example pakage

Answer 1

You are probably using IntelliJ IDEA and mean ( expected, not ) expected as stated in your subject line.

This is a glitch in IDEA's AspectJ and Spring AOP support. If you just ignore it, the aspect will still work. I tried, it works nicely:

package org.example;

public interface GoodBye {
  String getGoodBye();
}

package org.example;

public class DefaultGoodBye implements GoodBye {
  @Override
  public String getGoodBye() {
    return "Farewell";
  }
}

package org.example;

import org.springframework.stereotype.Component;

@Component
public class MyComponent {
  public void sayHello() {
    System.out.println("Hello");
  }

  public void sayGoodBye() {
    System.out.println("Good bye");
  }
}

package org.example;

import org.aspectj.lang.JoinPoint;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Before;
import org.aspectj.lang.annotation.DeclareParents;
import org.springframework.core.annotation.Order;
import org.springframework.stereotype.Component;

import java.util.Arrays;

@Aspect
@Order(value = 2)
@Component
public class SayAspect {
  @DeclareParents(value = "org.example..*", defaultImpl = DefaultGoodBye.class)
  private GoodBye goodBye;
  private int count = 0;

  @Before("execution(* org.example.MyComponent.sayHello())")
  public void beforeHello(JoinPoint joinPoint) {
    System.out.println("Before Hello");
    System.out.println(Arrays.toString(joinPoint.getTarget().getClass().getInterfaces()));
    System.out.println(Arrays.toString(joinPoint.getThis().getClass().getInterfaces()));
  }
}

package org.example;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.ConfigurableApplicationContext;

@SpringBootApplication
public class DemoApplication {
  public static void main(String[] args) {
    try (ConfigurableApplicationContext appContext = SpringApplication.run(DemoApplication.class, args)) {
      doStuff(appContext);
    }
  }

  private static void doStuff(ConfigurableApplicationContext appContext) {
    MyComponent myComponent = appContext.getBean(MyComponent.class);
    myComponent.sayHello();
    myComponent.sayGoodBye();
    System.out.println(((GoodBye) myComponent).getGoodBye());
  }
}

The console log says:

Before Hello
[]
[interface org.example.GoodBye, interface org.springframework.aop.SpringProxy, interface org.springframework.aop.framework.Advised, interface org.springframework.cglib.proxy.Factory]
Hello
Good bye
Farewell

As you can see,

• the before advice kicks in,
• the component proxy implements the GoodBye interface,
• the proxied component can be cast to GoodBye and
• calling the component's getGoodBye() method yields the expected result from the default implementation.