Spring之AOP详解

1. AOP简介

面向切面编程(也叫面向方面编程)：AspectOrientedProgramming(AOP)，是软件开发中的一个热点，也是Spring框架中的一个重要内容。利用AOP可以对业务逻辑的各个部分进行隔离，从而使得业务逻辑各部分之间的耦合度降低，提高程序的可重用性，同时提高了开发的效率。

主要的功能是：日志记录，性能统计，安全控制，事务处理，异常处理等等。

新建项目Spring403

手动增加会破环业务逻辑

StudentService.java

package com.andrew.service;
public interface StudentService {
    public void addStudent(String name);
}

StudentServiceImpl.java

package com.andrew.service.impl;
import com.andrew.service.StudentService;
public class StudentServiceImpl implements StudentService {
    @Override
    public void addStudent(String name) {
        System.out.println("日志：开始添加学生" + name);
        System.out.println("添加学生" + name);
        System.out.println("日志：完成学生" + name + "的添加");
    }
}

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"
    xsi:schemaLocation="http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans.xsd">
    <bean id="studentService" class="com.andrew.service.impl.StudentServiceImpl"></bean>
</beans>

JunitTest.java

package com.andrew.test;
import org.junit.Before;
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import com.andrew.service.StudentService;
public class JunitTest {
    private ApplicationContext ac;
    @Before
    public void setUp() throws Exception {
        ac = new ClassPathXmlApplicationContext("beans.xml");
    }
    @Test
    public void test1() {
        StudentService studentService = (StudentService) ac.getBean("studentService");
        studentService.addStudent("张三");
    }
}

运行结果：
日志：开始添加学生张三
添加学生张三
日志：完成学生张三的添加

2. SpringAOP实例

2.1) 前置通知

2.2) 后置通知

2.3) 环绕通知

2.4) 返回通知

2.5) 异常通知

新建项目Spring403-02

引入aop的声明
xmlns:aop="http://www.springframework.org/schema/aop"
http://www.springframework.org/schema/aop
http://www.springframework.org/schema/aop/spring-aop.xsd

导入aop jar包，右键buildPath
aopalliance.jar
aspectjweaver-1.6.6.jar
spring-aspects-4.0.6.RELEASE.jar

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="com.andrew.advice.StudentServiceAspect"></bean>
    <bean id="studentService" class="com.andrew.service.impl.StudentServiceImpl"></bean>
    <aop:config>
        <aop:aspect id="studentServiceAspect" ref="studentServiceAspect">
            <aop:pointcut expression="execution(* com.andrew.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>

StudentServiceAspect.java

package com.andrew.advice;
import org.aspectj.lang.JoinPoint;
import org.aspectj.lang.ProceedingJoinPoint;
public class StudentServiceAspect {
    public void doBefore(JoinPoint jp) {
        System.out.println("aop before 类名:" + jp.getTarget().getClass().getName());
        System.out.println("aop before 方法名：" + jp.getSignature().getName());
        System.out.println("aop before 开始添加学生：" + jp.getArgs()[0]);
    }
    public void doAfter(JoinPoint jp) {
        System.out.println("aop after 类名:" + jp.getTarget().getClass().getName());
        System.out.println("aop after 方法名：" + jp.getSignature().getName());
        System.out.println("aop after 学生添加完成：" + jp.getArgs()[0]);
    }
    public Object doAround(ProceedingJoinPoint pjp) throws Throwable {
        System.out.println("aop around 添加学生前");
        Object retVal = pjp.proceed();
        System.out.println(retVal);
        System.out.println("aop around 添加学生后");
        return retVal;
    }
    public void doAfterReturning(JoinPoint jp) {
        System.out.println("aop after returning 返回通知");
    }
    public void doAfterThrowing(JoinPoint jp, Throwable ex) {
        System.out.println("aop after throwing 异常通知");
        System.out.println("aop after throwing 异常信息：" + ex.getMessage());
    }
}

StudentService.java

package com.andrew.service;
public interface StudentService {
    public void addStudent(String name);
}

Test.java

package com.andrew.test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import com.andrew.service.StudentService;
public class Test {
    public static void main(String[] args) {
        ApplicationContext ac = new ClassPathXmlApplicationContext("beans.xml");
        StudentService studentService = (StudentService) ac.getBean("studentService");
        studentService.addStudent("张三");
    }
}

1) StudentServiceImpl.java

package com.andrew.service.impl;

import com.andrew.service.StudentService;
public class StudentServiceImpl implements StudentService {
    @Override
    public void addStudent(String name) {
        System.out.println("添加学生" + name);
    }
}

Test.java运行结果：
aop before 类名:com.andrew.service.impl.StudentServiceImpl
aop before 方法名：addStudent
aop before 开始添加学生：张三
aop around 添加学生前
添加学生张三
aop after returning 返回通知
null
aop around 添加学生后
aop after 类名:com.andrew.service.impl.StudentServiceImpl
aop after 方法名：addStudent
aop after 学生添加完成：张三

2) StudentServiceImpl.java

package com.andrew.service.impl;
import com.andrew.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);
    }
}

Test.java运行结果：
aop before 类名:com.andrew.service.impl.StudentServiceImpl
aop before 方法名：addStudent
aop before 开始添加学生：张三
aop around 添加学生前
添加学生张三
aop after throwing 异常通知
aop after throwing 异常信息：/ by zero
aop after 类名:com.andrew.service.impl.StudentServiceImpl
aop after 方法名：addStudent
aop after 学生添加完成：张三
Exception in thread "main" java.lang.ArithmeticException: / by zero
...