Spring aop入门

AOP核心概念

1、横切关注点

对哪些方法进行拦截，拦截后怎么处理，这些关注点称之为横切关注点

2、切面（aspect）

类是对物体特征的抽象，切面就是对横切关注点的抽象

3、连接点（joinpoint）

被拦截到的点，因为Spring只支持方法类型的连接点，所以在Spring中连接点指的就是被拦截到的方法，实际上连接点还可以是字段或者构造器

4、切入点（pointcut）

对连接点进行拦截的定义

5、通知（advice）

所谓通知指的就是指拦截到连接点之后要执行的代码，通知分为前置、后置、异常、最终、环绕通知五类

6、目标对象

代理的目标对象

7、织入（weave）

将切面应用到目标对象并导致代理对象创建的过程

8、引入（introduction）

在不修改代码的前提下，引入可以在运行期为类动态地添加一些方法或字段

进入实例代码 

1、

package com.longteng.lesson2.dao;

import org.aspectj.lang.ProceedingJoinPoint;

public interface HelloWorld {
    void printHelloWorld();
    void doPrint();
}

2、

package com.longteng.lesson2.dao.impl;

import com.longteng.lesson2.dao.HelloWorld;

public class HelloWorldImpl implements HelloWorld {
    @Override
    public void printHelloWorld() {
        System.out.println("HelloWorldImpl:printHelloWorld()------------");
    }

    @Override
    public void doPrint() {
        System.out.println("HelloWorldImpl:doPrint()------------");
    }
}

3、

package com.longteng.lesson2.dao.impl;

import com.longteng.lesson2.dao.HelloWorld;

public class HelloWorldImpl1 implements HelloWorld {
    @Override
    public void printHelloWorld() {
        System.out.println("HelloWorldImpl1:printHelloWorld()------------");
    }

    @Override
    public void doPrint() {
        System.out.println("HelloWorldImpl1:doPrint()------------");
    }
}

4、

package com.longteng.lesson2.service;

public class TimeHandler {
    public void startTime()
    {
        System.out.println("CurrentTime = " + System.currentTimeMillis());
    }
    public void endTime()
    {
        try {
            Thread.sleep(3);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        System.out.println("EndTime = " + System.currentTimeMillis());
    }
}

5、

<?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"
       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 http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">

    <bean id="helloWorldImpl" class="com.longteng.lesson2.dao.impl.HelloWorldImpl"></bean>
    <bean id="helloWorldImpl1" class="com.longteng.lesson2.dao.impl.HelloWorldImpl1"></bean>
    <bean id="timeHandler" class="com.longteng.lesson2.service.TimeHandler"> </bean>
    <aop:config>
        <aop:aspect id="time" ref="timeHandler" order="1">
            <aop:pointcut id="addTime" expression="execution(* com.longteng.lesson2.dao.impl.HelloWorldImpl*.*(..))" />
            <aop:before method="startTime" pointcut-ref="addTime" />
            <aop:after method="endTime" pointcut-ref="addTime" />
        </aop:aspect>

    </aop:config>

</beans>

6、

package com.longteng.lesson2.dao;

import org.junit.Before;
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class AopTest {
    ApplicationContext context;
    @Before
    public void initApplication(){
        context = new ClassPathXmlApplicationContext("aop.xml");
    }
    @Test
    public void test(){
        HelloWorld helloWorld1 =(HelloWorld) context.getBean("helloWorldImpl");
        helloWorld1.doPrint();
        helloWorld1.printHelloWorld();
        System.out.println("----------------------------------------");
        HelloWorld helloWorld2 =(HelloWorld) context.getBean("helloWorldImpl1");
        helloWorld2.doPrint();
        helloWorld2.printHelloWorld();
    }
}

7、测试结果

13:09:28.726 [main] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Returning cached instance of singleton bean 'helloWorldImpl'
13:09:28.734 [main] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Returning cached instance of singleton bean 'timeHandler'
CurrentTime = 1544504968735
HelloWorldImpl:doPrint()------------
13:09:28.735 [main] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Returning cached instance of singleton bean 'timeHandler'
EndTime = 1544504968738
13:09:28.738 [main] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Returning cached instance of singleton bean 'timeHandler'
CurrentTime = 1544504968738
HelloWorldImpl:printHelloWorld()------------
13:09:28.738 [main] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Returning cached instance of singleton bean 'timeHandler'
EndTime = 1544504968741
----------------------------------------
13:09:28.741 [main] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Returning cached instance of singleton bean 'helloWorldImpl1'
13:09:28.741 [main] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Returning cached instance of singleton bean 'timeHandler'
CurrentTime = 1544504968741
HelloWorldImpl1:doPrint()------------
13:09:28.741 [main] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Returning cached instance of singleton bean 'timeHandler'
EndTime = 1544504968745
13:09:28.745 [main] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Returning cached instance of singleton bean 'timeHandler'
CurrentTime = 1544504968745
HelloWorldImpl1:printHelloWorld()------------
13:09:28.745 [main] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Returning cached instance of singleton bean 'timeHandler'
EndTime = 1544504968748

Process finished with exit code 0