Spring中Aspectj和Schema-based AOP混用引起的错误

         前几天要在项目中增加一个新功能用来监控某些模块的运行情况，自然就想到了使用Spring的AOP来实现。之前已经有类似的AOP代码，使用的是Schema-based形式配置的，也就是在Spring的ApplicationContext.xml中加入了：

       <bean id="handlerBeanNameAutoProxyCreator"
		class="org.springframework.aop.framework.autoproxy.BeanNameAutoProxyCreator">
		<property name="beanNames">
			<list>
				<value>sampleService</value>
			</list>
		</property>
		<property name="interceptorNames">
			<list>
				<value>sampleAdvice</value>
			</list>
		</property>
	</bean>        

<context:component-scan base-package="com.nokia.myapp"/>

        这次要加的功能需要监控很多类，如果按照这个配置，就需要在beanNames的list中增加很多bean，并且还要修改原来的sampleAdvice代码判断是否是属于sampleService，无疑增加了程序的复杂度，这不是我想要的。这时就考虑使用AspectJ的Annotation，编程迅速，不会破坏现在的代码结构，也易于以后的维护。按照Spring Reference Document中@AspectJ Support章节的例子，很快写好了代码：

package com.nokia.myapp.aop.monitor;

import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.Signature;
import org.aspectj.lang.annotation.Around;
import org.aspectj.lang.annotation.Aspect;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

@Aspect
public class NewAspectjAOP{
	private Logger logger = LoggerFactory.getLogger("profile");
	
	@Around("execution(* com.nokia.myapp.client..*.*(..))")
	public Object serviceProfile(ProceedingJoinPoint pjp) throws Throwable {
		//Do something before method execution
		
		Object ret = null;
		Throwable th = null;
		
		try {
			ret = pjp.proceed();
		} catch(Throwable thr){
			th = thr;
		}
		
		//Do something after method execution
		
		if(th != null){
			throw th;
		}
		
		return ret;
	}
}

 ERROR [org.springframework.web.servlet.DispatcherServlet] [Thread-2] Context initialization failed
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'service1' defined in file [/opt/myapp/bin/WEB-INF/classes/com/nokia/myapp/Service1.class]: Instantiation of bean failed; nested exception is org.springframework.beans.BeanInstantiationException: Could not instantiate bean class [com.nokia.myapp.Service1]: Constructor threw exception; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'service2': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: private com.nokia.myapp.Service1 com.nokia.myapp.Service2.locationService; nested exception is org.springframework.beans.factory.BeanCurrentlyInCreationException: Error creating bean with name 'service1': Requested bean is currently in creation: Is there an unresolvable circular reference?
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateBean(AbstractAutowireCapableBeanFactory.java:965) ~[spring-beans-3.0.5.RELEASE.jar:3.0.5.RELEASE]
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:911) ~[spring-beans-3.0.5.RELEASE.jar:3.0.5.RELEASE]
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:485) ~[spring-beans-3.0.5.RELEASE.jar:3.0.5.RELEASE]
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:456) ~[spring-beans-3.0.5.RELEASE.jar:3.0.5.RELEASE]
……

        根据提示查看代码，发现在Service2中通过@Autowired引入了Service1，而在Service1中也通过@Autowired引入了Service2。于是去掉了Service2在Service1中引用，而后在需要用的时候通过ApplicationContext.getBean(String beanName)获取Service2。

        修正了上面的错误，再次测试，程序可以正常启动，但是有些程序运行出现了奇怪的问题：每次ApplicationConext.getBeansOfType(Class class)获取sampleService时，总是会获取到其他的Bean，导致程序运行异常（不过本地Eclipse中运行测试没有问题）。使用Eclipse的Remote Debug功能连到开发服务器上调试，发现其他类getClass()获取的都是class com.nokia.myapp.Service2$$EnhancerByCGLIB$$ccadc5e，而SampleService却是$Proxy119。百思不得其解。

        最后请教了对Spring框架很熟悉的同事，终于发现了问题的原因：

由于@AspectJ声明的AOP和在Spring的配置文件中配置的AOP都监测了同一个类SampleService。于是在运行过程中，SampleService实现了CGLIB的三个接口，而根据Spring Reference Document中Proxying mechanisms：

Spring AOP uses either JDK dynamic proxies or CGLIB to create the proxy for a given target object. (JDK dynamic proxies are preferred whenever you have a choice).

If the target object to be proxied implements at least one interface then a JDK dynamic proxy will be used. All of the interfaces implemented by the target type will be proxied. If the target object does not implement any interfaces then a CGLIB proxy will be created.

          找到了问题，修复就很容易了，只需要指定ProxyFactoryBean的proxyTargetClass属性：

<bean id="handlerBeanNameAutoProxyCreator"
class="org.springframework.aop.framework.autoproxy.BeanNameAutoProxyCreator" p:proxyTargetClass="true">