（转）实例简述Spring AOP之间对AspectJ语法的支持（转）

Spring的AOP可以通过对@AspectJ注解的支持和在XML中配置来实现,本文通过实例简述如何在Spring中使用AspectJ.
一:使用AspectJ注解:
1,启用对AspectJ的支持:
通过在Spring的配置中引入下列元素来启用Spring对AspectJ的支持：
<aop:aspectj-autoproxy />
或者(如果不是使用XSD的话)
<bean class="org.springframework.aop.aspectj.annotation.AnnotationAwareAspectJAutoProxyCreator" />
2,声明一个带有@Aspect注解的类,在这个类中声明那些方法需要被'关注'(利用@Pointcut),在那些时机点进行关注(利用@Before,@AfterReturning等等...),执行'切入'的方法
3,在Spring的配置文件中定义这个'切面'类:任意带有一个@Aspect切面（拥有@Aspect注解）的bean都将被Spring自动识别并用于配置在Spring AOP.
4,使用被Spring管理的bean,在执行被'关注'的方法时,'切入'的方法就会被执行.
一个完整的例子:
需要被'切入'的类:

 public class Monkey {
     public void stealPeaches(String name) {
         System.out.println(" Monkey " + name + " is stealling peaches...");
     }  
 
     public void stealCorns(String name) {
         System.out.println(" Monkey " + name + " is stealling corns...");
     }
 }  

切面类
 1 @Aspect
 public class Guardian {
     @Pointcut("execution(* com.test.spring.aspectj.Monkey.stealPeaches(..))")
     public void guardOrchard() {
     }  
 
     @Before(value = "guardOrchard()")
     public void guardOrchardBefore() {
         System.out.println("Guardian spotted a monkey is approaching the orchard...");
     }  
 
     @AfterReturning("guardOrchard() && args(name,..)")
     public void guardOrchardAfter(String name) {
         System.out.println("Guardian caught a monkey stealling peaches whoes name is " + name + "...");
     }
     @Around("guardOrchard() && args(name,..)")
     public void guardOrchardAround(ProceedingJoinPoint joinpoint,String name) {
         System.out.println("Guardian guardOrchardAround started ... " + name);
         try {
             joinpoint.proceed();
         } catch (Throwable e) {
             System.out.println("Guardian guardOrchardAround exception happened ... " + name);
         }
         System.out.println("Guardian guardOrchardAround completed ... " + name);
     }
     @Pointcut("execution(* com.test.spring.aspectj.Monkey.stealCorns(..))")
     public void guardFarm() {
     }  
 
     @Before(value = "guardFarm()")
     public void guardFarmBefore() {
         System.out.println("Guardian spotted a monkey is approaching the farm...");
     }  
 
     @AfterReturning("guardFarm() && args(name,..)")
     public void guardFarmAfter(String name) {
         System.out.println("Guardian caught a monkey stealling corns whoes name is " + name + "...");
     }
 }  

配置文件

 <?xml version="1.0" encoding="UTF-8"?>
 <beans xmlns="http://www.springframework.org/schema/beans"
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:aop="http://www.springframework.org/schema/aop"
     xsi:schemaLocation="
          http://www.springframework.org/schema/beans
          http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
          http://www.springframework.org/schema/aop
          http://www.springframework.org/schema/aop/spring-aop-3.0.xsd">
     <!--
         <aop:aspectj-autoproxy /> equals to <bean
         class="org.springframework.aop.aspectj.annotation.AnnotationAwareAspectJAutoProxyCreator"
         />
     -->
     <aop:aspectj-autoproxy />
     <bean id="guardian" class="com.test.spring.aspectj.Guardian" />  
 
     <bean id="monkey" class="com.test.spring.aspectj.Monkey" />  
 
 </beans>  

使用bean

 ApplicationContext context = new ClassPathXmlApplicationContext("conf/aspectJAppcontext.xml");
         Monkey monkey = (Monkey) context.getBean("monkey");
         try {
             monkey.stealPeaches("mighty monkey");
             monkey.stealCorns("mighty monkey");
         } catch (Exception e) {
         }  

运行结果

 Guardian spotted a monkey is approaching the orchard...
 Guardian guardOrchardAround started ... mighty monkey
 Monkey mighty monkey is stealling peaches...
 Guardian caught a monkey stealling peaches whoes name is mighty monkey...
 Guardian guardOrchardAround completed ... mighty monkey
 Guardian spotted a monkey is approaching the farm...
  Monkey mighty monkey is stealling corns...
 Guardian caught a monkey stealling corns whoes name is mighty monkey...  

二:通过XML配置AspectJ实现AOP:在java类中定义要被'方面'调用的切入方法,在XML中配置.
例子:被'切入'的类,普通java类:

 public class Monkey {
     public void stealPeaches(String name) {
         System.out.println(" Monkey " + name + " is stealling peaches...");
     }  
 
     public void stealCorns(String name,int numberToSteal) {
         System.out.println(" Monkey " + name + " is stealling corns...");
     }
 }  

定义要被'方面'调用的切入方法的类:

 public class XMLGuardian {
     public void guardOrchardBefore() {
         System.out.println("XMLGuardian spotted a monkey is approaching the orchard...");
     }  
 
     public void guardOrchardAfter() {
         System.out.println("XMLGuardian caught a monkey stealling peaches whoes name is ...");
     }
     public void guardFarmBefore() {
         System.out.println("XMLGuardian spotted a monkey is approaching the farm...");
     }
     public void guardFarmAfter(String name,int num,Object retVal) {
         System.out.println("XMLGuardian caught a monkey stealling " + num + " corns whoes name is ..." + name );
     }
 }  

XML配置:

 <?xml version="1.0" encoding="UTF-8"?>
 <beans xmlns="http://www.springframework.org/schema/beans"
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:aop="http://www.springframework.org/schema/aop"
     xsi:schemaLocation="
          http://www.springframework.org/schema/beans
          http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
          http://www.springframework.org/schema/aop
          http://www.springframework.org/schema/aop/spring-aop-3.0.xsd">  
 
     <bean id="guardian" class="com.test.spring.aspectj.XMLGuardian" />
     <bean id="monkey" class="com.test.spring.aspectj.Monkey" />
     <aop:config>  
 
         <aop:aspect id="myAspect" ref="guardian">
             <aop:pointcut id="guardOrchard"
                 expression="execution(* com.test.spring.aspectj.Monkey.stealPeaches(..))" />  
 
             <aop:before pointcut-ref="guardOrchard" method="guardOrchardBefore" />
             <aop:after-returning pointcut-ref="guardOrchard" method="guardOrchardAfter"/>  
 
             <aop:pointcut id="guardFarm"
                 expression="execution(* com.test.spring.aspectj.Monkey.stealCorns(..))" />  
 
             <aop:before pointcut-ref="guardFarm" method="guardFarmBefore" />
             <aop:after-returning pointcut="execution(* com.test.spring.aspectj.Monkey.stealCorns(..)) and args(name,num,..)" returning="retVal"
             method="guardFarmAfter" />
             <!--  arg-names="name1" -->
         </aop:aspect>
     </aop:config>
 </beans>  

客户端测试代码:

 ApplicationContext context = new ClassPathXmlApplicationContext("conf/xmlaspectJAppcontext.xml");
         Monkey monkey = (Monkey) context.getBean("monkey");
         try {
             monkey.stealPeaches("mighty monkey");
             monkey.stealCorns("mighty monkey",3);
         } catch (Exception e) {
         }  

运行结果

 XMLGuardian spotted a monkey is approaching the orchard...
  Monkey mighty monkey is stealling peaches...
 XMLGuardian caught a monkey stealling peaches whoes name is ...
 XMLGuardian spotted a monkey is approaching the farm...
  Monkey mighty monkey is stealling corns...
 XMLGuardian caught a monkey stealling 3 corns whoes name is ...mighty monkey  

Spring AOP 只支持对bean的方法级的'切入',而且AOP的内部机制和AspectJ有所区别,Spring主要是通过动态代理来实现AOP,使用JDK的动态代理(如果被代理的bean是interface的话)或者CGLIB(如果如果被代理的bean不是interface的话).