spring中使用Aspectj进行切面编程

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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/>

maven工程要先添加相应的 Aspectj的依赖

<!--AOP-->
<dependency>
    <groupId>org.aspectj</groupId>
    <artifactId>aspectjrt</artifactId>
    <version>1.8.9</version>
</dependency>
<dependency>
    <groupId>org.aspectj</groupId>
    <artifactId>aspectjweaver</artifactId>
    <version>1.8.9</version>
</dependency>

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

@Aspect
public class AbcAspect {

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.

@Pointcut("execution (* com.sans.pc.reco(*))"
)
public void aspect() {}

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:

@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 <beanclass="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).