13.代理模式(Proxy Pattern)

using System;

namespace ConsoleApplication6
{
    class Program
    {
        static void Main(string[] args)
        {
            // 创建一个代理对象并发出请求            
            Person proxy = new Friend();            
            proxy.BuyProduct();            
            Console.Read();
        }
    }

    // 抽象主题角色
    public abstract class Person
    {
        public abstract void BuyProduct();
    }

    //真实买家
    public class RealBuyPerson : Person
    {
        public override void BuyProduct()
        {
            Console.WriteLine("真实买家买一个IPhone和一台苹果电脑");
        }
    }

    // 代理角色
    public class Friend : Person
    {
        RealBuyPerson realSubject;

        public override void BuyProduct()
        {      
            if (realSubject == null)
            {
                realSubject = new RealBuyPerson();
            }

            realSubject.BuyProduct();
            Console.WriteLine("调用代理类叫朋友去买");
            this.PreBuyProduct();     
            this.PostBuyProduct();
        }

        public void PreBuyProduct()
        {
            Console.WriteLine("朋友去买一个IPhone和一台苹果电脑");      
        }

        public void PostBuyProduct()
        {
            Console.WriteLine("朋友去把IPhone和一台苹果电脑交给真实买家");
        }
    }

 
}