代理模式 Proxy Pattern 委托模式

Provide a surrogate or placeholder for another object to control access to it.

为其他对象提供一种代理以控制对这个对象的访问。

抽象主题角色（Subject）：该角色是真实主题和代理主题的共同接口，以便在任何可以使用真实主题的地方都可以使用代理主题。

package com.DesignPattern.Structural.Proxy;public interface Subject {// 定义一个请求方法public void request();
}

代理主题角色（Proxy Subject）：也叫做委托类，代理类，该角色负责控制对真实主题的引用，负责在需要的时候创建或删除真实主题对象，并且在真实主题角色处理完毕前后做预处理和善后处理工作。

package com.DesignPattern.Structural.Proxy;public class ProxySubject implements Subject {private Subject subject;public ProxySubject(Subject subject) {this.subject = subject;}// 实现请求方法@Overridepublic void request() {this.beforeRequest();subject.request();this.afterRequest();}//请求前的操作private void beforeRequest() {// 预处理}//请求后的操作private void afterRequest() {// 善后处理}
}

真实主题角色（Real Subject）：该角色也叫做被委托角色、被代理角色，是业务逻辑的具体执行者。

package com.DesignPattern.Structural.Proxy;public class RealSubject implements Subject {@Overridepublic void request() {// 业务处理逻辑System.out.println("realSubject request");}
}

代理模式的实例

IGamePlayer.java

package com.DesignPattern.Structural.Proxy;public interface IGamePlayer {public void killBoss();// 杀怪public void upGrade();// 升级
}

GamePlayer.java

package com.DesignPattern.Structural.Proxy;public class GamePlayer implements IGamePlayer {private String name = "";public GamePlayer(String name) {this.name = name;}@Overridepublic void killBoss() {System.out.println(this.name + " killBoss");}@Overridepublic void upGrade() {System.out.println(this.name + " upgrade level 1");}}

GamePlayerProxy.java

package com.DesignPattern.Structural.Proxy;import java.util.Date;public class GamePlayerProxy implements IGamePlayer {private IGamePlayer player=null;public GamePlayerProxy(IGamePlayer player){this.player=player;}//记录打怪时间private void log(){System.out.println("打怪时间"+new Date().toString());}@Overridepublic void killBoss() {this.log();player.killBoss();}@Overridepublic void upGrade() {player.upGrade();this.count();}//计算升级所用的时间private void count(){System.out.println("upgrade cost time!");}}

ClientDemo.java

package com.DesignPattern.Structural.Proxy;public class ClientDemo {public static void main(String[] args){IGamePlayer player=new GamePlayer("Tom");IGamePlayer proxy=new GamePlayerProxy(player);proxy.killBoss();proxy.upGrade();}
}