牛奶报纸...

  1using System;
  2using System.Collections;
  3using System.Text;
  4
  5namespace TestConsoleApplication
  6{
  7    public class Class2
  8    {
  9        public static void Main(string[] args)
 10        {
 11            NewsPaperSender nsper = new NewsPaperSender();
 12            MilkSender milker = new MilkSender();
 13
 14            Subscriber sb1 = new Subscriber("person1");
 15            Subscriber sb2 = new Subscriber("person2");
 16            Subscriber sb3 = new Subscriber("person3");
 17            Subscriber sb4 = new Subscriber("person4");
 18
 19
 20            nsper.Subscribe(new sendEverthing(sb1.PutMilkIn));
 21            nsper.Subscribe(new sendEverthing(sb1.PutMilkIn));
 22            milker.Subscribe(new sendEverthing(sb1.PutMilkIn));
 23            milker.Subscribe(new sendEverthing(sb4.PutMilkIn));
 24            nsper.SendNewsPaper();
 25            milker.SendMilk();
 26            Console.Read();
 27        }
 28
 29        定义2个接口#region 定义2个接口
 30        public interface IMilkBox
 31        {
 32            void PutMilkIn(string s);
 33        }
 34
 35        public interface INewsPaperBox
 36        {
 37            void PutNewsPaperIn(string s);
 38        }
 39        #endregion
 40
 41        实现类#region 实现类
 42        public class Subscriber : INewsPaperBox, IMilkBox
 43        {
 44            public string name;
 45            /**//// <summary>
 46            /// 构造函数（牛奶报纸接受者名赋值）
 47            /// </summary>
 48            /// <param name="name">收到着名字</param>
 49            public Subscriber(string name)
 50            {
 51                this.name = name;
 52            }
 53            /**//// <summary>
 54            /// 实现收到报纸
 55            /// </summary>
 56            /// <param name="s"></param>
 57            public void PutNewsPaperIn(string s)
 58            {
 59                Console.WriteLine("{0}在NewsPaper箱里收到送来的{1}", name, s);
 60            }
 61            /**//// <summary>
 62            /// 实现收牛奶
 63            /// </summary>
 64            /// <param name="s"></param>
 65            public void PutMilkIn(string s)
 66            {
 67                Console.WriteLine("{0}在MilkI箱里收到送来的{1}", name, s);
 68            }
 69        }
 70        #endregion
 71
 72        public delegate void sendEverthing(string s);
 73
 74        送牛奶和报纸#region 送牛奶和报纸
 75        /**//// <summary>
 76        /// NewsPaperSender
 77        /// </summary>
 78        public class NewsPaperSender
 79        {
 80            public event sendEverthing newsPaperHandler;
 81            //protected ArrayList al = new ArrayList();
 82
 83            public void SendNewsPaper()
 84            {
 85                //foreach (INewsPaperBox newsPaperBox in al)
 86                //{
 87                //    newsPaperBox.PutNewsPaperIn("NewsPaper");
 88                //}
 89                if (newsPaperHandler!=null)
 90                {
 91                    newsPaperHandler("NewsPaper");
 92                }
 93            }
 94
 95            public void Subscribe(sendEverthing sd)
 96            {
 97                newsPaperHandler += sd;
 98            }
 99        }
        /**//// <summary>
        /// MilkSender
        /// </summary>
        public class MilkSender
        {
            //protected ArrayList subscribers = new ArrayList();
            public event sendEverthing sendMileHandler;

            public void SendMilk()
            {
                //foreach (IMilkBox milkBox in subscribers)
                //{
                //    milkBox.PutMilkIn("MilkI");
                //}
                if (sendMileHandler!=null)
                {
                    sendMileHandler("Milk");
                }
            }

            public void Subscribe(sendEverthing sd)
            {
                //subscribers.Add(milkBox);
                sendMileHandler += sd;
            }
        }
        #endregion
    }
}

很好的解释了为什么需要委托...

转自: http://www.cnblogs.com/zhenyulu/articles/76706.html