實現AOP功能的封裝與配置的小框架

內容

java基礎鞏固筆記 - 實現AOP功能的封裝與配置的小框架

設計（目錄）：

XXX = java.util.ArrayList中

代碼

Advice接口

MyAdvice類

BeanFactory類

ProxyFactoryBean類

AopFrameWorkTest類

輸出

本文經過是動態代理實現的AOP功能的封裝與配置的小框架.加深對動態代理和AOP編程的理解

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設計

根據配置文件的鍵xxx對應的值(類全名)建立相應類的對象。

當且僅當xxx對應的值爲com.iot.proxy.aopframework.ProxyFactoryBean時，則生成相應的動態代理類對象。代理對象的目標類和通知實現類分別由xxx.target和xxx.advice配置

配置文件

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config.propertiest位於aopframework包下

xxx表明要加載的類

xxx.advice表明通知接口的某個實現類

xxx.target表明委託類

#xxx=java.util.ArrayList

xxx=com.iot.proxy.aopframework.ProxyFactoryBean

xxx.advice=com.iot.proxy.MyAdvice

xxx.target=java.util.ArrayList

包:com.iot.proxy.aopframework,有以下幾個類/接口：

BeanFactory,用於讀取配置文件，根據配置建立相應的對象

ProxyFactoryBean,用於生成代理對象，含有兩個私有屬性:目標和通知

Advice,通知接口，用於把切面的代碼以對象的形式傳遞給InvocationHandler的的invoke方法

MyAdvice,Advice接口的一個實現類，打印執行方法前的時間及執行耗時

AopFrameWorkTest，測試效果

代碼

Advice接口

package com.iot.proxy.aopframework;

import java.lang.reflect.Method;

/**

* Created by brian on 2016/2/2.

*/

public interface Advice {

void beforeMethod(Method method);

void aftereMethod(Method method);

}

MyAdvice類

package com.iot.proxy.aopframework;

import java.lang.reflect.Method;

/**

* Created by brian on 2016/2/2.

*/

public class MyAdvice implements Advice{

long beginTime = 0 ;

@Override

public void beforeMethod(Method method) {

System.out.println(method.getName()+" before at "+beginTime);

beginTime = System.currentTimeMillis();

}

@Override

public void aftereMethod(Method method) {

long endTime = System.currentTimeMillis();

System.out.println(method.getName()+" cost total "+ (endTime-beginTime));

}

}

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BeanFactory類

package com.iot.proxy.aopframework;

import java.io.IOException;

import java.io.InputStream;

import java.util.Properties;

/**

* Created by brian on 2016/2/2.

*/

public class BeanFactory {

Properties properties = new Properties();

public BeanFactory(InputStream inputStream){

try {

properties.load(inputStream);

} catch (IOException e) {

e.printStackTrace();

}

}

public Object getBean(String name){

String className = properties.getProperty(name);

Object bean = null;

try {

Class clazz = Class.forName(className);

bean = clazz.newInstance();

} catch (ClassNotFoundException e) {

e.printStackTrace();

} catch (InstantiationException e) {

e.printStackTrace();

} catch (IllegalAccessException e) {

e.printStackTrace();

}

if (bean instanceof ProxyFactoryBean){

ProxyFactoryBean proxyFactoryBean = (ProxyFactoryBean)bean;

Advice advice = null;

Object target = null;

try {

advice = (Advice) Class.forName(properties.getProperty(name+".advice")).newInstance();

target = Class.forName(properties.getProperty(name+".target")).newInstance();

} catch (InstantiationException e) {

e.printStackTrace();

} catch (IllegalAccessException e) {

e.printStackTrace();

} catch (ClassNotFoundException e) {

e.printStackTrace();

}

proxyFactoryBean.setAdvice(advice);

proxyFactoryBean.setTarget(target);

Object proxy = ((ProxyFactoryBean) bean).getProxy();

return proxy;

}

return bean;

}

}

ProxyFactoryBean類

package com.iot.proxy.aopframework;

import java.lang.reflect.InvocationHandler;

import java.lang.reflect.Method;

import java.lang.reflect.Proxy;

/**

* Created by brian on 2016/2/3.

*/

public class ProxyFactoryBean {

private Object target;

private Advice advice;

public Object getProxy(){

Object proxy = Proxy.newProxyInstance(

target.getClass().getClassLoader(),

target.getClass().getInterfaces(),

new InvocationHandler() {

@Override

public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {

advice.beforeMethod(method);

Object retVal = method.invoke(target,args);

advice.aftereMethod(method);

return retVal;

}

}

);

return proxy;

}

public Object getTarget() {

return target;

}

public void setTarget(Object target) {

this.target = target;

}

public Advice getAdvice() {

return advice;

}

public void setAdvice(Advice advice) {

this.advice = advice;

}

}

AopFrameWorkTest類

package com.iot.proxy.aopframework;

import java.io.InputStream;

import java.util.Collection;

/**

* Created by brian on 2016/2/3.

*/

public class AopFrameWorkTest {

public static void main(String[] args) {

InputStream inputStream = AopFrameWorkTest.class.getResourceAsStream("config.properties");

Object bean = new BeanFactory(inputStream).getBean("xxx");

System.out.println(bean.getClass().getName());

((Collection) bean).clear();

}

}

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輸出

• 配置

xxx=com.iot.proxy.aopframework.ProxyFactoryBean

輸出爲：

com.sun.proxy.$Proxy0clear before at 0clear cost total 0

• 配置

xxx=java.util.ArrayList

輸出爲：

java.util.ArrayList

能夠看出，只改變配置文件，就可改變代碼的運行結果，從而達到靈活的效果