Spring - Autowire fails when adding an aspect-backed annotation to overridden method - spring

Question

I have an authentication service implementing org.springframework.security.core.userdetails.UserDetailsService and defined as:
#Service
public class AuthService implements UserDetailsService {
// Autowires ..
#Override
//#Logged(successMessage = "User %s logged in")
public UserDetails loadUserByUsername(String username) { .. }
}
It is autowired into an extension of WebSecurityConfigurerAdapter and used to configure authentication:
// Annotations ...
public class SecurityConfig extends WebSecurityConfigurerAdapter {
#Autowired
private AuthService authService;
#Override
public void configure(AuthenticationManagerBuilder auth) throws Exception {
BCryptPasswordEncoder encoder = new BCryptPasswordEncoder();
auth.userDetailsService(authService).passwordEncoder(encoder);
}
// Other security config stuff ...
}
And last, I have created a custom annotation called #Logged, that is picked up by an aspect that applies around advice to the annotated method and performs some logging logic. Lets just say that if you pass only one argument to it, it will log successful returns.
Applying the #Logged annotation to the overriden AuthService.loadUserByUsername method causes the application to crash on startup, displaying the message about not being able to autowire AuthService into the SecurityConfig. Everything works flawlessly if I don't put the annotation to that overriden method - authentication works (complete with autowiring) and logging annotation works in other parts of the system.
Question
Why is this happening and can it be fixed?
I would really like to log that exact method using my fancy logging anotation.
Thanks :)
Technical details
Spring 4 with Boot, Jetty 9
Stack trace (part of):
2014-09-22 12:41:05 WARN AbstractLifeCycle - FAILED org.springframework.boot.context.embedded.jetty.ServletContextInitializerConfiguration$InitializerListener#8bb473: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'org.springframework.security.config.annotation.web.configuration.WebSecurityConfiguration': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire method: public void org.springframework.security.config.annotation.web.configuration.WebSecurityConfiguration.setFilterChainProxySecurityConfigurer(org.springframework.security.config.annotation.ObjectPostProcessor,java.util.List) throws java.lang.Exception; nested exception is org.springframework.beans.factory.BeanExpressionException: Expression parsing failed; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'securityConfig': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: private com.bluepixelflag.services.AuthService com.bluepixelflag.config.SecurityConfig.authService; nested exception is java.lang.IllegalArgumentException: Can not set com.bluepixelflag.services.AuthService field com.bluepixelflag.config.SecurityConfig.authService to com.sun.proxy.$Proxy90

Answer 1

Spring is using a proxy to add aspects to AuthService. Without the annotation it would just use a simple class.
Change
private AuthService authService;
to
private UserDetailsService authService;
and it ought to work. Or, use cglib proxies instead of JDK dynamic proxies.
Aside: the point of using aspects for logging is to try to avoid one line of code per logging call. If you use an aspect annotation for every method call you want logged, you haven't saved any complexity (in fact you've increased it), and might as well just call a logger in code.