java设计模式-代理模式小结

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1.代理模式目录结构

2.以卖书为例，由厂家（RealSubject）交由书店（代理Proxy）销售。买书去找书店就行了，而不必知道具体厂家地址。而书店不仅仅只是买书而已，还可以在买书基础上打打广告，送送券什么的。

3.结构

厂家和代理都有卖书，所以可以抽象出Subject接口，实现其sell 函数；

而代理除了sell 之外，还可以添加自己的函数及动作，打折或送券神马的。

4.具体实现

Subject.java

public interface Subject {public void sell();}

RealSubject.java

public class RealSubject implements Subject{@Overridepublic void sell() {// TODO Auto-generated method stubSystem.out.println("sell book!");}}

ProxySubject.java

public class ProxySubject implements Subject{private RealSubject realSubject;public ProxySubject() {// TODO Auto-generated constructor stubthis.realSubject = new RealSubject();}@Overridepublic void sell() {// TODO Auto-generated method stubif (realSubject  != null) {// 卖书之前打广告guanggao();realSubject.sell();// 买书之后送券quan();}}private void guanggao() {// TODO Auto-generated method stubSystem.out.println("da guang gao");}private void quan() {// TODO Auto-generated method stubSystem.out.println("song quan");}}

Client.java

public class Client {public static void main(String[] args) {ProxySubject proxySubject = new ProxySubject();proxySubject.sell();}}

动态代理：

Subject 与 RealSubject 与上面一样。

MyHandler.java

import java.lang.reflect.InvocationHandler;import java.lang.reflect.Method;public class MyHandler implements InvocationHandler{private RealSubject realSubject;public MyHandler() {// TODO Auto-generated constructor stubrealSubject = new RealSubject();}public RealSubject getRealSubject(){return realSubject;}@Overridepublic Object invoke(Object proxy, Method method, Object[] args)throws Throwable {// TODO Auto-generated method stubObject result = null;if (realSubject != null) {guanggao();result = method.invoke(realSubject, args);quan();}return result;}private void guanggao() {// TODO Auto-generated method stubSystem.out.println("da guang gao");}private void quan() {// TODO Auto-generated method stubSystem.out.println("quan");}}

Client.java

public class Client {/** * @param args */public static void main(String[] args) {// TODO Auto-generated method stubMyHandler handler = new MyHandler();Subject proxy = (Subject) Proxy.newProxyInstance(handler.getRealSubject().getClass().getClassLoader(), handler.getRealSubject().getClass().getInterfaces(), handler);proxy.sell();}}

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