//代理模式
public class Proxy implements Subject{private Subject subject;public Proxy(){//关系在编译时确定subject = new RealSubject();}public void doAction(){….subject.doAction();….}
}
//代理的客户
public class Client{public static void main(String[] args){//客户不知道代理委托了另一个对象Subject subject = new Proxy();…}
}

//AccessValidator.cs
using System;  namespace ProxySample
{  class AccessValidator  {  //模拟实现登录验证  public bool Validate(string userId)   {  Console.WriteLine("在数据库中验证用户'" + userId + "'是否是合法用户？");  if (userId.Equals("杨过")) {  Console.WriteLine("'{0}'登录成功！",userId);  return true;  }  else {  Console.WriteLine("'{0}'登录失败！", userId);  return false;  }  }  }
}
//Logger.cs
using System;  namespace ProxySample
{  class Logger  {  //模拟实现日志记录  public void Log(string userId) {  Console.WriteLine("更新数据库，用户'{0}'查询次数加1！",userId);  }  }
}
//Searcher.cs
namespace ProxySample
{  interface Searcher  {  string DoSearch(string userId, string keyword);  }
}
//RealSearcher.cs
using System;  namespace ProxySample
{  class RealSearcher : Searcher  {  //模拟查询商务信息  public string DoSearch(string userId, string keyword) {  Console.WriteLine("用户'{0}'使用关键词'{1}'查询商务信息！",userId,keyword);  return "返回具体内容";  }  }
}

//ProxySearcher.cs
namespace ProxySample
{  class ProxySearcher : Searcher  {  private RealSearcher searcher = new RealSearcher(); //维持一个对真实主题的引用  private AccessValidator validator;  private Logger logger;  public string DoSearch(string userId, string keyword)  {  //如果身份验证成功，则执行查询  if (this.Validate(userId))  {  string result = searcher.DoSearch(userId, keyword); //调用真实主题对象的查询方法  this.Log(userId); //记录查询日志  return result; //返回查询结果
            }  else  {  return null;  }  }  //创建访问验证对象并调用其Validate()方法实现身份验证  public bool Validate(string userId)  {  validator = new AccessValidator();  return validator.Validate(userId);  }  //创建日志记录对象并调用其Log()方法实现日志记录  public void Log(string userId)  {  logger = new Logger();  logger.Log(userId);  }  }
}