Spring Aop实例

在上篇博文中，我向大家介绍了Aop重要概念和教程，这回给出代码示例。

一、XML方式

1. TestAspect：切面类

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package com.spring.aop;

import org.aspectj.lang.JoinPoint;

import org.aspectj.lang.ProceedingJoinPoint;

public class TestAspect {

public void doAfter(JoinPoint jp) {

System.out.println("log Ending method: " + jp.getTarget().getClass().getName() + "." + jp.getSignature().getName());

}

public Object doAround(ProceedingJoinPoint pjp) throws Throwable {

long time = System.currentTimeMillis();

Object retVal = pjp.proceed();

time = System.currentTimeMillis() - time;

System.out.println("process time: " + time + " ms");

return retVal;

}

public void doBefore(JoinPoint jp) {

System.out.println("log Begining method: " + jp.getTarget().getClass().getName() + "." + jp.getSignature().getName());

}

public void doThrowing(JoinPoint jp, Throwable ex) {

System.out.println("method " + jp.getTarget().getClass().getName() + "." + jp.getSignature().getName() + " throw exception");

System.out.println(ex.getMessage());

}

}

2. AServiceImpl：目标对象

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package com.spring.service;

// 使用jdk动态代理

public class AServiceImpl implements AService {

public void barA() {

System.out.println("AServiceImpl.barA()");

}

public void fooA(String _msg) {

System.out.println("AServiceImpl.fooA(msg:" + _msg + ")");

}

}

3. BServiceImpl：目标对象

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package com.spring.service;

// 使用cglib

public class BServiceImpl {

public void barB(String _msg, int _type) {

System.out.println("BServiceImpl.barB(msg:" + _msg + " type:" + _type + ")");

if (_type == 1)

throw new IllegalArgumentException("测试异常");

}

public void fooB() {

System.out.println("BServiceImpl.fooB()");

}

}

4. ApplicationContext：Spring配置文件

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<?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"

xmlns:context="http://www.springframework.org/schema/context"

xmlns:tx="http://www.springframework.org/schema/tx"

xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.1.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-3.1.xsd
http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.1.xsd
http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-3.1.xsd">

<aop:config>

<aop:aspect id="TestAspect" ref="aspectBean">

<!--配置com.spring.service包下所有类或接口的所有方法-->

<aop:pointcut id="businessService" expression="execution(* com.spring.service.*.*(..))" />

<aop:before pointcut-ref="businessService" method="doBefore"/>

<aop:after pointcut-ref="businessService" method="doAfter"/>

<aop:around pointcut-ref="businessService" method="doAround"/>

<aop:after-throwing pointcut-ref="businessService" method="doThrowing" throwing="ex"/>

</aop:aspect>

</aop:config>

<bean id="aspectBean" class="com.spring.aop.TestAspect" />

<bean id="aService" class="com.spring.service.AServiceImpl"></bean>

<bean id="bService" class="com.spring.service.BServiceImpl"></bean>

</beans>

二、注解（Annotation）方式

1. TestAnnotationAspect

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package com.spring.aop;

import org.aspectj.lang.ProceedingJoinPoint;

import org.aspectj.lang.annotation.After;

import org.aspectj.lang.annotation.AfterReturning;

import org.aspectj.lang.annotation.AfterThrowing;

import org.aspectj.lang.annotation.Around;

import org.aspectj.lang.annotation.Aspect;

import org.aspectj.lang.annotation.Before;

import org.aspectj.lang.annotation.Pointcut;

@Aspect

public class TestAnnotationAspect {

@Pointcut("execution(* com.spring.service.*.*(..))")

private void pointCutMethod() {

}

//声明前置通知

@Before("pointCutMethod()")

public void doBefore() {

System.out.println("前置通知");

}

//声明后置通知

@AfterReturning(pointcut = "pointCutMethod()", returning = "result")

public void doAfterReturning(String result) {

System.out.println("后置通知");

System.out.println("---" + result + "---");

}

//声明例外通知

@AfterThrowing(pointcut = "pointCutMethod()", throwing = "e")

public void doAfterThrowing(Exception e) {

System.out.println("例外通知");

System.out.println(e.getMessage());

}

//声明最终通知

@After("pointCutMethod()")

public void doAfter() {

System.out.println("最终通知");

}

//声明环绕通知

@Around("pointCutMethod()")

public Object doAround(ProceedingJoinPoint pjp) throws Throwable {

System.out.println("进入方法---环绕通知");

Object o = pjp.proceed();

System.out.println("退出方法---环绕通知");

return o;

}

}

2. ApplicationContext：Spring配置文件

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<?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"

xmlns:context="http://www.springframework.org/schema/context"

xmlns:tx="http://www.springframework.org/schema/tx"

xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.1.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-3.1.xsd
http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.1.xsd
http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-3.1.xsd">

<aop:aspectj-autoproxy></aop:aspectj-autoproxy>

<bean class="org.springframework.aop.aspectj.annotation.AnnotationAwareAspectJAutoProxyCreator" />

<bean id="aspectBean" class="com.spring.aop.TestAnnotationAspect" />

<bean id="aService" class="com.spring.service.AServiceImpl"></bean>

<bean id="bService" class="com.spring.service.BServiceImpl"></bean>

</beans>

关于切入点表达式，大家需要好好练习才能深入理解其中含义。即使看的懂，但是写起来却非常麻烦，并没有想象中那么简单。

最后，再告诉大家：

任何通知（Advice）方法可以将第一个参数定义为 org.aspectj.lang.JoinPoint类型。JoinPoint接口提供了一系列有用的方法， 比如 getArgs() （返回方法参数）、getThis() （返回代理对象）、getTarget() （返回目标）、getSignature() （返回正在被通知的方法相关信息）和 toString() （打印出正在被通知的方法的有用信息。

其中getSignature()返回的Signature对象可强制转换为MethodSignature，其功能非常强大，能获取包括参数名称在内的一切方法信息。