Spring Aop實例

在上篇博文中，我向你們介紹了Aop重要概念和教程，這回給出代碼示例。

1、XML方式

1. TestAspect：切面類

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：目標對象

package com.spring.service;  
  
// 使用jdk動態代理  
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：目標對象

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("測試異常");  
    }  
  
    public void fooB() {  
        System.out.println("BServiceImpl.fooB()");  
    }  
  
}

4. ApplicationContext：spring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"  
    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包下全部類或接口的全部方法-->  
            <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>

2、註解（Annotation）方式

1. TestAnnotationAspect

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() {  
    }  
  
    //聲明前置通知  
    @Before("pointCutMethod()")  
    public void doBefore() {  
        System.out.println("前置通知");  
    }  
  
    //聲明後置通知  
    @AfterReturning(pointcut = "pointCutMethod()", returning = "result")  
    public void doAfterReturning(String result) {  
        System.out.println("後置通知");  
        System.out.println("---" + result + "---");  
    }  
  
    //聲明例外通知  
    @AfterThrowing(pointcut = "pointCutMethod()", throwing = "e")  
    public void doAfterThrowing(Exception e) {  
        System.out.println("例外通知");  
        System.out.println(e.getMessage());  
    }  
  
    //聲明最終通知  
    @After("pointCutMethod()")  
    public void doAfter() {  
        System.out.println("最終通知");  
    }  
  
    //聲明環繞通知  
    @Around("pointCutMethod()")  
    public Object doAround(ProceedingJoinPoint pjp) throws Throwable {  
        System.out.println("進入方法---環繞通知");  
        Object o = pjp.proceed();  
        System.out.println("退出方法---環繞通知");  
        return o;  
    }  
}

2. ApplicationContext：Spring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"  
    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>

關於切入點表達式，你們須要好好練習才能深刻理解其中含義。即便看的懂，可是寫起來卻很是麻煩，並無想象中那麼簡單。

最後，再告訴你們：

任何通知（Advice）方法能夠將第一個參數定義爲 org.aspectj.lang.JoinPoint類型。JoinPoint接口提供了一系列有用的方法， 好比 getArgs() （返回方法參數）、getThis() （返回代理對象）、getTarget() （返回目標）、getSignature() （返回正在被通知的方法相關信息）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對象可強制轉換爲MethodSignature，其功能很是強大，能獲取包括參數名稱在內的一切方法信息。