Spring AOP - Access to Repositories autowired field by reflection

Question

It's for the first time that Inside an AspectJ I may need to access a local private autowired field of a Repository in order to do some stuff on >exactly< that instance.

I created a pointcut that focuses on each method of every @Repository annotated class. When the pointcut fires, I get the current class instance from which I want to get the bean field.

This is the way:

@Repository
public class MyDao {

    @Autowired
    private MyBean bean;

    public List<Label> getSomething() {
        // does something...
    }
}


@Aspect
@Component
public class MyAspect {

    @Pointcut("within(@org.springframework.stereotype.Repository *)")
    public void repositories() {
    }

    @Before("repositories()")
    public void setDatabase(JoinPoint joinPoint) {
        try {
            Field field = ReflectionUtils.findField(joinPoint.getThis().getClass(), "bean"); // OK since here - joinPoint.getThis().getClass() -> MyDao
            ReflectionUtils.makeAccessible(field); // Still OK
            Object fieldValue = ReflectionUtils.getField(field, joinPoint.getThis());
            System.out.println(fieldValue == null); // true

            // should do some stuff with the "fieldValue"
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

}

fieldValue is always null even if I create something like private | public | package String something = "blablabla"; instead.

I have ensured that "bean" is actually instantiated when the application starts (verified with the debugger).

I followed How to read the value of a private field from a different class in Java?

What I am missing? | Is it possible? | Are there any different ways?

Autowiring takes place after all beans are instantiated so it appears your code is running before that point. What is it that you need to do that you can't do via configuration? — Paul, Dec 31 '18 at 18:15
@grimi try this approach https://stackoverflow.com/questions/7819410/access-class-variable-in-aspect-class — springbootlearner, Dec 31 '18 at 19:25
@Paul Thankyou for the reply! I need to manipulate the "bean" attribute (invoke a function that changes his status globally) — Andrea Grimandi, Jan 01 '19 at 08:47
@springbootlearner My hero! I will post my solution beneath asap. Thanks! — Andrea Grimandi, Jan 01 '19 at 09:10

score 0 · Accepted Answer · answered Jan 01 '19 at 09:49

@springbootlearner suggested this approach access class variable in aspect class

All I had to do is to replace the joinPoint.getThis() with joinPoint.getTarget()

And the final solution is:

@Aspect
@Component
public class MyAspect {

    /**
     *
     */
    @Pointcut("within(@org.springframework.stereotype.Repository *)")
    public void repositories() {
    }

    /**
     * @param joinPoint
     */
    @Before("repositories()")
    public void setDatabase(JoinPoint joinPoint) {
       Object target = joinPoint.getTarget();

       // find the "MyBean" field
       Field myBeanField = Arrays.stream(target.getClass().getDeclaredFields())
            .filter(predicate -> predicate.getType().equals(MyBean.class)).findFirst().orElseGet(null);

       if (myBeanField != null) {
           myBeanField.setAccessible(true);
           try {
              MyBean bean = (MyBean) myBeanField.get(target);// do stuff
           } catch (IllegalAccessException e) {
               e.printStackTrace();
           }
       }
    }

}

Spring AOP - Access to Repositories autowired field by reflection

1 Answers1

Linked