Spring基于XML配置AOP

目录结构：

D:\Java\IdeaProjects\JavaProj\SpringHelloWorld\src\cn\edu\bjut\service\StudentService.java

package cn.edu.bjut.service;

/**
 * Created by N3verL4nd on 2017/3/24.
 */
public interface StudentService {
    public void addStudent(String name);
}

D:\Java\IdeaProjects\JavaProj\SpringHelloWorld\src\cn\edu\bjut\service\impl\StudentServiceImpl.java

package cn.edu.bjut.service.impl;

import cn.edu.bjut.service.StudentService;

/**
 * Created by N3verL4nd on 2017/3/24.
 */
public class StudentServiceImpl implements StudentService {
    @Override
    public void addStudent(String name) {
        System.out.println("[添加学生]：" + name);
        //触发异常通知
//        System.out.println( 1 / 0);
    }
}

D:\Java\IdeaProjects\JavaProj\SpringHelloWorld\src\cn\edu\bjut\advice\StudentServiceAspect.java

package cn.edu.bjut.advice;

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

import java.util.Arrays;

/**
 * Created by N3verL4nd on 2017/3/24.
 */
public class StudentServiceAspect {

    //前置通知
    public void doBefore(JoinPoint jp) {
        System.out.println("--------------前置通知-------------");
        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：" + Arrays.toString(jp.getArgs()));
        System.out.println("-----------------------------------");
    }

    //后置通知
    public void doAfter(JoinPoint jp) {
        System.out.println("--------------后置通知-------------");
        System.out.println("学生添加完成!");
        System.out.println("-----------------------------------");
    }

    //环绕通知
    public Object doAround(ProceedingJoinPoint pjp) throws Throwable {
        System.out.println("--------------环绕通知-------------");
        System.out.println("添加学生前：");
        Object retVal = null;
        retVal= pjp.proceed();
        System.out.println("返回值：" + retVal);
        System.out.println("添加学生后!");
        System.out.println("-----------------------------------");
        return retVal;
    }

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

    //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());
        System.out.println("-----------------------------------");
    }
}

D:\Java\IdeaProjects\JavaProj\SpringHelloWorld\src\cn\edu\bjut\test\T.java

package cn.edu.bjut.test;

import cn.edu.bjut.service.StudentService;
import org.junit.Before;
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

/**
 * Created by N3verL4nd on 2017/3/24.
 */
public class T {
    private ApplicationContext context = null;

    @Before
    public void setUp() {
        context = new ClassPathXmlApplicationContext("beans.xml");
    }

    @Test
    public void test() {
        StudentService studentService = (StudentService) context.getBean("studentService");
        studentService.addStudent("lgh");
    }
}

D:\Java\IdeaProjects\JavaProj\SpringHelloWorld\src\beans.xml

<?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.xsd">

    <bean id="studentServiceAspect" class="cn.edu.bjut.advice.StudentServiceAspect"/>

    <bean id="studentService" class="cn.edu.bjut.service.impl.StudentServiceImpl"/>

    <aop:config>
        <aop:aspect ref="studentServiceAspect">
            <aop:pointcut id="businessService" expression="execution(public void cn.edu.bjut.service.impl.StudentServiceImpl.addStudent(String))"/>
            <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>

输出：

--------------前置通知-------------
类名：cn.edu.bjut.service.impl.StudentServiceImpl
方法名：addStudent
开始添加学生：[lgh]
-----------------------------------
--------------环绕通知-------------
添加学生前：
[添加学生]：lgh
--------------返回通知-------------
-----------------------------------
返回值：null
添加学生后!
-----------------------------------
--------------后置通知-------------
学生添加完成!
-----------------------------------

介绍一下org/aspectj/lang/JoinPoint.java

AspectJ使用org.aspectj.lang.JoinPoint接口表示目标类连接点对象，如果是环绕增强时，使用org.aspectj.lang.ProceedingJoinPoint表示连接点对象，该类是JoinPoint的子接口。

任何一个增强方法都可以通过将第一个入参声明为JoinPoint访问到连接点上下文的信息。我们先来了解一下这两个接口的主要方法： 

1)JoinPoint 
java.lang.Object[] getArgs()：获取连接点方法运行时的入参列表； 
Signature getSignature() ：获取连接点的方法签名对象； 
java.lang.Object getTarget() ：获取连接点所在的目标对象； 
java.lang.Object getThis() ：获取代理对象本身； 
2)ProceedingJoinPoint 
ProceedingJoinPoint继承JoinPoint子接口，它新增了两个用于执行连接点方法的方法： 
java.lang.Object proceed() throws java.lang.Throwable：通过反射执行目标对象的连接点处的方法； 
java.lang.Object proceed(java.lang.Object[] args) throws java.lang.Throwable：通过反射执行目标对象连接点处的方法，不过使用新的入参替换原来的入参。