Spring AOP at Service Layer

Question

I need some help with Spring AOP. I've the following code:

---

@Service
public class UserSecurityService implements UserDetailsService {

    @Autowired
    private UserService userService;
    ....
}

---

@Service
public class UserService extends CrudService<User, UserRepository> {

    public UserService() {
        super();
    }

    @Autowired
    public UserService(UserRepository repository) {
        super(repository);
        this.repository = repository;
    }
    ....
}

---

@Repository
interface UserRepository extends JpaRepository<User, String> {
     ...
}

---

application-context.xml

<import resource="classpath*:spring/application-context-db.xml" />
<import resource="classpath*:spring/application-context-aop.xml" />
<import resource="classpath*:spring/application-context-mail.xml" />
<import resource="application-context-security.xml" />

<context:component-scan base-package="com.xpto">
    <context:exclude-filter type="annotation" expression="org.springframework.stereotype.Controller" />
    <context:exclude-filter type="annotation" expression="org.springframework.stereotype.Repository" />
</context:component-scan>

---

application-context-aop.xml

<aop:aspectj-autoproxy />
<aop:config>
    <aop:aspect id="serviceLoggingAspect" ref="serviceLoggingAspectBean">
        <aop:pointcut id="servicePointcut"
                expression="@within(org.springframework.stereotype.Service)" />

        <aop:before method="before" pointcut-ref="servicePointcut" />
        <aop:after-returning method="afterReturning" pointcut-ref="servicePointcut" returning="result" />
        <aop:after-throwing method="afterThrowing" pointcut-ref="servicePointcut" throwing="exception" />
    </aop:aspect>
</aop:config>

---

When I try to load my application at Tomcat, I get the following exception:

Caused by: java.lang.IllegalArgumentException: Can not set com.xpto.user.service.UserService field com.xpto.user.security.service.UserSecurityService.userService to com.sun.proxy.$Proxy57
at sun.reflect.UnsafeFieldAccessorImpl.throwSetIllegalArgumentException(UnsafeFieldAccessorImpl.java:164)
at sun.reflect.UnsafeFieldAccessorImpl.throwSetIllegalArgumentException(UnsafeFieldAccessorImpl.java:168)
at sun.reflect.UnsafeObjectFieldAccessorImpl.set(UnsafeObjectFieldAccessorImpl.java:81)
at java.lang.reflect.Field.set(Field.java:680)
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:510)
... 35 more

---

I've the same configuration at Web layer to Logging my application and it works fine, but when I put AOP at Service layer I get this exception.

I'm using Spring MVC and at web.xml I configured to load two different contexts, one loads only @Controller and the other loads @Repository and @Service.

Answer 1

You are not injecting an interface so you need to use CGLIB proxies, the spring reference manual states:

Spring AOP defaults to using standard J2SE dynamic proxies for AOP proxies. This enables any interface (or set of interfaces) to be proxied.

Spring AOP can also use CGLIB proxies. This is necessary to proxy classes, rather than interfaces. CGLIB is used by default if a business object does not implement an interface. As it is good practice to program to interfaces rather than classes, business classes normally will implement one or more business interfaces.

Spring has decided to use a J2SE proxy (com.sun.proxy.$Proxy57) probably because CrudService implements an interface. To force the use of CGLIB you can tweak your XML:

<aop:aspectj-autoproxy proxy-target-class="true"/>