峰Spring4学习（6）spring AOP的应用例子

一、AOP简介：

二、AOP实例：

三、使用的例子

需求：在student添加的前后，打印日志信息；

0）spring AOP需要引用的jar包：

1）StudentService.java接口：

package com.cy.service;

public interface StudentService {
    public void addStudent(String name);
}

2）StudentServiceImpl.java实现类：

package com.cy.service.impl;

import com.cy.service.StudentService;

public class StudentServiceImpl implements StudentService {

    @Override
    public void addStudent(String name) {
        System.out.println("添加学生"+name);
    }

}

3）StudentServiceAspect.java切面类：

package com.cy.advice;

import org.aspectj.lang.JoinPoint;
import org.aspectj.lang.ProceedingJoinPoint;

public class StudentServiceAspect {

    //前置通知，方法执行之前
    public void doBefore(JoinPoint jp){
        System.out.println("类名：" + jp.getTarget().getClass().getName());
        System.out.println("方法名：" + jp.getSignature().getName());
        System.out.println("开始添加学生：" + jp.getArgs()[0]);
    }

    //后置通知 方法完成之后
    public void doAfter(JoinPoint jp){
        System.out.println("类名：" + jp.getTarget().getClass().getName());
        System.out.println("方法名：" + jp.getSignature().getName());
        System.out.println("完成添加学生：" + jp.getArgs()[0]);
    }

    //环绕通知  可以在业务方法的前后添加逻辑
    public Object doAround(ProceedingJoinPoint pjp) throws Throwable{
        System.out.println("添加学生前");
        Object retVal = pjp.proceed();    //retVal为StudentServiceImpl.addStudent(String name)方法的返回值
                                          //因为返回值为void，所以console打印null
        System.out.println("添加学生后");
        System.out.println(retVal);
        return retVal;
    }

    //返回通知
    public void doAfterReturning(JoinPoint jp){
        System.out.println("返回通知");
    }

    //异常通知
    public void doAfterThrowing(JoinPoint jp, Throwable ex){
        System.out.println("异常通知");
        System.out.println("异常信息：" + ex.getMessage());
    }
}

4）beans.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.xsd
                  http://www.springframework.org/schema/aop
                   http://www.springframework.org/schema/aop/spring-aop-2.5.xsd">

     <bean id="studentService" class="com.cy.service.impl.StudentServiceImpl"></bean>
     <bean id="studentServiceAspect" class="com.cy.advice.StudentServiceAspect"></bean>

     <aop:config>
         <aop:aspect id="studentServiceAspect" ref="studentServiceAspect">
             <aop:pointcut expression="execution(* com.cy.service..*.*(..))" id="businessService"/>
             <aop:before method="doBefore" pointcut-ref="businessService"/>
             <aop:after method="doAfter" pointcut-ref="businessService"/>
             <aop:around method="doAround" pointcut-ref="businessService"/>
             <aop:after-returning method="doAfterReturning" pointcut-ref="businessService"/>
             <aop:after-throwing method="doAfterThrowing" pointcut-ref="businessService" throwing="ex"/>
         </aop:aspect>
     </aop:config>

</beans>

5）测试代码：

public class T {

    public static void main(String[] args) {
        ApplicationContext ac = new ClassPathXmlApplicationContext("beans.xml");
        StudentService studentService = (StudentService) ac.getBean("studentService");
        studentService.addStudent("张三");
    }

}

1）没有异常抛出时，没有异常通知；console打印：

2）addStudent方法中构造异常，有异常通知，console打印：

StudentServiceImpl.java:

package com.cy.service.impl;

import com.cy.service.StudentService;

public class StudentServiceImpl implements StudentService {

    @Override
    public void addStudent(String name) {
        System.out.println("添加学生"+name);
        System.out.println(1/0);
    }

}

doAround方法中抛出异常是这句话：

--  Object retVal = pjp.proceed();