关于C# 设计模式 Proxy 代理模式

using System;
using System.Collections.Generic;
using System.Text;
using System.Threading;

///Prototype（原型）模式 用于解决在直接访问对象不方便或不符合要求时，为这个对象提供一种代理，以控制对该对象的访问。
///add by jzh 2007-04-15
namespace DesignPattern
{
    /// <summary>
    ///    Summary description for Client.
    /// </summary>
    abstract class CommonSubject
    {
        abstract public void Request();
    }

    class ActualSubject : CommonSubject
    {
        public ActualSubject()
        {
            Console.WriteLine("开始构造");
            Thread.Sleep(1000);
            Console.WriteLine("完成构造");
        }

        override public void Request()
        {
            Console.WriteLine("执行请求");
        }
    }

    class Proxy : CommonSubject
    {
        ActualSubject actualSubject;

        override public void Request()
        {
            if (actualSubject == null)
                actualSubject = new ActualSubject();
            actualSubject.Request();
        }

    }

    public class Client
    {
        public static void Main(string[] args)
        {
            Proxy proxy = new Proxy();
            proxy.Request();

            Console.ReadLine();
        }
    }
}