Autowired dependency not injected in Aspect in Spring MVC

Question

I am not able to @Autowire the Service Layer Instance in Aspect. In Aspect the reference to the @Autowired bean is NULL and it throws NullPointerException. Any help will be much appreciated. I think, I messed up with configuration.

Following is my servlet-context.xml:

<!-- Activates various annotations to be detected in bean classes -->
<context:annotation-config />
<context:spring-configured />       

<!-- Scans the classpath of this application for @Components to deploy as beans -->
<context:component-scan base-package="xx.yy" />

<!--  an @AspectJ aspect will be interpreted as an aspect by Spring AOP and beans in the context will be advised accordingly -->
<aop:aspectj-autoproxy />

<beans:bean id="loggingAspect" class="xx.yy.aop.aspects.LoggingAspect" />
<beans:bean id="authenticationAspect" class="xx.yy.aop.aspects.AuthenticationAspect" />

<!-- Enables the Spring MVC @Controller programming model -->
<annotation-driven />

Following is my Aspect:

@Configurable
@Component
@Aspect
public class AuthenticationAspect {
private static final Logger logger = LoggerFactory.getLogger(AuthenticationAspect.class);

@Autowired
private LoginService loginService;

    //.... 
}

Here is my controller using the @Authentication Annotation defined above:

@Controller
@RequestMapping("/user")
public class UsersController {

@Autowired
private UserService userService;

@Authenticate
@RequestMapping(value="/{userId}/profile", method=RequestMethod.GET)    
public String displayUser(WebRequest webRequest, @PathVariable("userId") String userId, Model model) {
    User user = userService.findUser(Long.valueOf(userId));  
    model.addAttribute("user", user);
    model.addAttribute("AccordionMenuTab","5");
    model.addAttribute("selectedLink","profile");
    return "profile";
}

I am getting following exception:

Oct 8, 2011 3:12:48 AM org.apache.catalina.core.StandardWrapperValve invoke
SEVERE: Servlet.service() for servlet appServlet threw exception
java.lang.NullPointerException
    at xx.yy.controller.UsersController.displayUser_aroundBody1$advice(UsersController.java:28)
    at xx.yy.controller.UsersController.displayUser(UsersController.java:1)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at org.springframework.web.bind.annotation.support.HandlerMethodInvoker.invokeHandlerMethod(HandlerMethodInvoker.java:176)
    at org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.invokeHandlerMethod(AnnotationMethodHandlerAdapter.java:426)
    at org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.handle(AnnotationMethodHandlerAdapter.java:414)
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:790)
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:719)
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:644)
    at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:549)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:617)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298)
    at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:859)
    at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:588)
    at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)
    at java.lang.Thread.run(Thread.java:662)

Answer 1

See this piece of the documentation:

7.8.3 Configuring AspectJ aspects using Spring IoC

When using AspectJ aspects with Spring applications, it is natural to both want and expect to be able to configure such aspects using Spring. The AspectJ runtime itself is responsible for aspect creation, and the means of configuring the AspectJ created aspects via Spring depends on the AspectJ instantiation model (the 'per-xxx' clause) used by the aspect.

The majority of AspectJ aspects are singleton aspects. Configuration of these aspects is very easy: simply create a bean definition referencing the aspect type as normal, and include the bean attribute 'factory-method="aspectOf"'. This ensures that Spring obtains the aspect instance by asking AspectJ for it rather than trying to create an instance itself. For example:

<bean id="profiler" class="com.xyz.profiler.Profiler"
      factory-method="aspectOf" />