AOP works only with @Autowired annotation

Question

I have the following spring controller code:

@Controller
@RequestMapping("/")
public class MainController {
    UserService user = new UserService();

    @GetMapping("/home")
    public String goFirstPage(){
        user.showUserName(new User("Mike"));
        return"firstpage";
    }

}

and the following aspect:

@Aspect
@Component
@Order(1)
public class UserAspect {


    @Before("execution(public void com.project.aopmaven.services.UserService.showUserName(..))")
    public void logUser(){
        System.out.println("Logging User");
    }

}

It doesn't work, "Logging User" message is not shown (even the UserService object is instantiated in the controller class). But, when we add the @Autowired annotation to the UserService defined in the controller it works!

@Autowired
UserService user = new UserService();

Can anyone explain this?

Answer 1

Spring AOP allows using AOP on Spring beans, not on random objects. And it's based on proxies: instead of injecting the actual implementation of the bean, Spring injects a proxy that wraps the actual implementation, and invokes the aspects before/after invoking the wrapped bean implementation.

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