代理模式 c#

using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;

namespace ConsoleApplication1
{
    class Program
    {
        /// <summary>
        /// 抽象角色
        /// </summary>
        public abstract class Role
        {
            public abstract void BuyProduct();
        }


        /// <summary>
        /// 真实角色
        /// </summary>
        public class RealBuyRole : Role
        {
            public override void BuyProduct()
            {
                Console.WriteLine("buy something");
            }
        }

        /// <summary>
        /// 代理角色
        /// </summary>
        public class Proxy:Role
        {
            private RealBuyRole realRole;

            public override void BuyProduct()
            {
                if (realRole == null)
                {
                    realRole = new RealBuyRole();
                }


                this.PreBuyProduct();

                // 调用真实角色方法
                realRole.BuyProduct();

                this.PostBuyProduct();
            }

            /// <summary>
            /// 代理角色的前置行为
            /// </summary>
            public void PreBuyProduct()
            {

                Console.WriteLine("买东西前做的事情");
            }


            /// <summary>
            /// 代理角色的后置行为
            /// </summary>
            public void PostBuyProduct()
            {
                Console.WriteLine("买东西后做的事情");
            }
        }

        static void Main(string[] args)
        {
            Role proxy = new Proxy();
            proxy.BuyProduct();

        }
    }
}