春季：无AspectJ的拦截

Question

In my Spring 4 application, I have a class like this:

class Address {

   public getAdress(){
      ...
      List<Town> towns = getTowns();
      ...
   }

   @CustomAnnotation
   private List<Town> getTowns(){

   }
}

With AspectJ I can easily intercept the getAdress() call. The problem is with getTowns() that is not intercepted.

There are solutions such as Load-Time Weaving but that is difficult to tune and I don't what to reconfigure my application.

How can I capture any call made to any method annotated with CustomAnnotation without AspectJ ?

Regards

PS: I know that there is a workaround with self-reference but I don't find it very "clean".

Answer 1

Extracting interface:

interface TempIfc{
    public getAdress();
}

class Address implements TempIfc{

   @Override
   public getAdress(){
      ...
      List<Town> towns = getTowns();
      ...
   }

   @CustomAnnotation
   private List<Town> getTowns(){

   }
}

Adding config:

<bean id="tgt" class="Address">
    <!-- your bean properties here -->
</bean>

<bean id="proxified" class="org.springframework.aop.framework.ProxyFactoryBean">
    <property name="proxyInterfaces" value="TempIfc"/>
    <property name="target" ref="tgt"/>
    <property name="interceptorNames">
        <list>
            <value>myInterceptor</value>
        </list>
    </property>
</bean> 

<bean id="myInterceptor" class="MyMethodInterceptor"/>

<!-- Example of usage with some service -->
<bean id="someYourService" class="Service">
     <property name="adress" ref="proxified" />
</bean>

And finally interceptor:

public class MyMethodInterceptor implements  org.aopalliance.intercept.MethodInterceptor{

    public Object invoke(org.aopalliance.intercept.MethodInvocation invocation){

        System.out.println("Before calling any TempIfc method ");

        // Actionally, you may use getMethod, getArguments here to explore details, or modify arguments

        Object result = invocation.proceed(); //also it is not obligatory to call real method

        System.out.println("After calling any TempIfc method ");
        //you may modify result of invocation here

        return result;
    }
}

Here is the docs and javadocs about ProxyFactoryBean.

Answer 2

I think we can use ControlFlowPointcut provided by Spring.

ControlFlowPointcut looks at stacktrace and matches the pointcut only if it finds a particular method in the stacktrace. essentially pointcut is matched only when a method is called in a particular context.

In this case, we can create a pointcut like

ControlFlowPointcut cf = new ControlFlowPointcut(MyClass.class, "method1");

now, using ProxyFactory create a proxy on MyClass instance and call method1().

In above case, only method2() will be advised since it is called from method1().