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如何自己实现spring aop相似的功能

2018-03-20 00:00 661 查看

AOP（Aspect Oriented Programming），即面向切面编程，它利用一种称为"横切"的技术，把软件系统分为两个部分：核心关注点和横切关注点，用来实现诸如权限认证、日志、事务等功能。简单讲就是在指定类的指定方法前后增加通用代码，减少冗余增强功能。

手动实现：

被代理的目标接口

package com.xxx.service;

public interface RunningService {

public void running();
}

被代理的目标实现类

package com.xxx.service.impl;

import org.springframework.stereotype.Component;

import com.xxx.service.RunningService;

@Component
public class RunningServiceImpl implements RunningService {
@Override
public void running() {
System.out.println("do something");
}
}

需要增加的通用操作类

package com.xxx.proxy;

import org.springframework.stereotype.Component;

@Component
public class Aop {

public void before(){
System.out.println("before!");
}

public void after(){
System.out.println("after!");
}
}

代理工厂类

package com.xxx.proxy;

import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;

public class ProxyFactory {
public static Object newProxyInstance(final Object target,final Aop aop){

ClassLoader classLoader = target.getClass().getClassLoader();
Class<?>[] interfaces = target.getClass().getInterfaces();
InvocationHandler invocationHandler = new InvocationHandler() {

@Override
public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
aop.before();
Object result = method.invoke(target, args);
aop.after();
return result;
}
};

return Proxy.newProxyInstance(classLoader, interfaces, invocationHandler);
}
}

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:p="http://www.springframework.org/schema/p"
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/context http://www.springframework.org/schema/context/spring-context.xsd"
default-autowire="byType">

<!-- 开启注解扫描 -->
<context:component-scan base-package="com.xxx.proxy"></context:component-scan>
<!-- 调用工厂方法，返回runningService的代理对象 -->
<bean id="runningService_proxy" class="com.xxx.proxy.ProxyFactory" factory-method="newProxyInstance">
<constructor-arg index="0" type="java.lang.Object" ref="runningServiceImpl"></constructor-arg>
<constructor-arg index="1" type="com.xxx.proxy.Aop" ref="aop"></constructor-arg>
</bean>
</beans>

测试类

package com.xxx.proxy;

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

import com.xxx.proxy.service.RunningService;

public class TestAop {
@Test
public void test(){
ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("classpath:applicationContext.xml");
RunningService run = (RunningService)context.getBean("runningService_proxy");
run.running();
}
}

运行结果

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标签： proxy spring aop java

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