猫大叫一声，所有的老鼠都开始逃跑，主人被惊醒

程序设计: 猫大叫一声，所有的老鼠都开始逃跑，主人被惊醒。(C#语言)
要求：  
1.要有联动性，老鼠和主人的行为是被动的。
2.考虑可扩展性，猫的叫声可能引起其他联动效应。


 要点：1. 联动效果，运行代码只要执行Cat.Cryed()方法。

　　    2. 对老鼠和主人进行抽象

  1 public interface Observer
  2     {
  3         void Response();    //观察者的响应，如是老鼠见到猫的反映
  4     }
  5     public interface Subject
  6     {
  7         void AimAt(Observer obs);  //针对哪些观察者，这里指猫的要扑捉的对象---老鼠
  8     }
  9     public class Mouse : Observer
 10     {
 11         private string name;
 12         public Mouse(string name, Subject subj)
 13         {           
 14             this.name = name;
 15             subj.AimAt(this);
 16         }
 17         
 18         public void Response()
 19         {
 20             Console.WriteLine(name + " attempt to escape!");
 21         }
 22     }
 23     public class Master : Observer
 24     {   
 25         public Master(Subject subj)
 26         {           
 27             subj.AimAt(this);
 28         }
 29         
 30         public void Response()
 31         {
 32             Console.WriteLine("Host waken!");
 33         }  
 34     }
 35  
 36     public class Cat : Subject
 37     {
 38         private ArrayList observers;
 39         public Cat()
 40         {   
 41             this.observers = new ArrayList();
 42         }
 43         public void AimAt(Observer obs)
 44         {
 45             this.observers.Add(obs);
 46         }
 47         public void Cry()
 48         {
 49             Console.WriteLine("Cat cryed!");
 50             foreach (Observer obs in this.observers)
 51             {
 52                 obs.Response();
 53             }
 54         }
 55     }
 56     class MainClass
 57     {       
 58         static void Main(string[] args)
 59         {
 60             Cat cat = new Cat();
 61             Mouse mouse1 = new Mouse("mouse1", cat);
 62             Mouse mouse2 = new Mouse("mouse2", cat);
 63             Master master = new Master(cat);
 64             cat.Cry();
 65         }
 66     }
 67 
 68 
 69 //---------------------------------------------------------------------------------------------
 70 
 71 设计方法二: 使用event -- delegate设计..
 72     public delegate void SubEventHandler();
 73     public abstract class Subject
 74     {
 75         public event SubEventHandler SubEvent;
 76         protected void FireAway()
 77         {
 78             if (this.SubEvent != null)
 79                 this.SubEvent();
 80         }   
 81     }
 82     public class Cat : Subject
 83     {  
 84         public void Cry()
 85         {
 86             Console.WriteLine("cat cryed.");
 87             this.FireAway();
 88         }
 89     }
 90     public abstract class Observer
 91     {
 92         public Observer(Subject sub)
 93         {
 94             sub.SubEvent += new SubEventHandler(Response);
 95         }
 96         public abstract void Response();    
 97     }
 98     public class Mouse : Observer
 99     {
100         private string name;
101         public Mouse(string name, Subject sub) : base(sub)
102         {   
103             this.name = name;
104         }
105         public override void Response()
106         {
107             Console.WriteLine(name + " attempt to escape!");
108         }
109     }
110     public class Master : Observer
111     {
112         public Master(Subject sub) : base(sub){}
113         public override void Response()
114         {
115             Console.WriteLine("host waken");
116         }
117     }
118     class Class1
119     {
120         static void Main(string[] args)
121         {
122             Cat cat = new Cat();
123             Mouse mouse1 = new Mouse("mouse1", cat);
124             Mouse mouse2 = new Mouse("mouse2", cat);
125             Master master = new Master(cat);
126             cat.Cry();
127         }
128 
129     }