C#中的觀察者模式

using System;
//
//程式設計: 貓大叫一聲，所有的老鼠都開始逃跑，主人被驚醒。(C#語言)
//要求： 
//1.要有聯動性，老鼠和主人的行為是被動的。
//2.考慮可擴充性，貓的叫聲可能引起其他聯動效應。
//
//要點：1. 聯動效果，運行代碼只要執行Cat.Cryed()方法。2. 對老鼠和主人進行抽象
//評分標準:
//<1>.構造出Cat、Mouse、Master三個類，並能使程式運行

//<2>從Mouse和Master中提取抽象
//<3>聯動效應，只要執行Cat.Cryed()就可以使老鼠逃跑，主人驚醒。

namespace cmdText
{
   /**//// <summary>
    /// EventCat 的摘要說明。
    /// </summary>
      public delegate void SubEventHandler();

      public abstract class Subject
      {
         public event SubEventHandler SubEvent;
         protected void FireAway()
         {
              if (this.SubEvent != null)
                  this.SubEvent();
           }  
       }

      public class Cat : Subject
      { 
          public void Cry()
          {
               Console.WriteLine("cat cryed.");
              this.FireAway();
           }
       }

      public abstract class Observer
      {
          public Observer(Subject sub)
          {
               sub.SubEvent += new SubEventHandler(Response);
           }
          public abstract void Response();   
       }

      public class Mouse : Observer
      {
         private string name;
         public Mouse(string name, Subject sub) : base(sub)
         {  
             this.name = name;
          }
         public override void Response()
         {
              Console.WriteLine(name + " attempt to escape!");
          }
      }

     public class Master : Observer
     {
         public Master(Subject sub) : base(sub){}
         public override void Response()
         {
              Console.WriteLine("host waken");
          }
      }

     class Class
     {
         static void Main(string[] args)
         {
              Cat cat = new Cat();
              Mouse mouse1 = new Mouse("mouse1", cat);
              Mouse mouse2 = new Mouse("mouse2", cat);
              Master master = new Master(cat);
              cat.Cry();
              Console.Read();
          }
 
      }
}