学习C#设计模式-Observer模式实现

C#设计模式-观察者observer模式实现 

题目：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>.构造出Cat、Mouse、Master三个类，并能使程序运行(2分)
             <2>从Mouse和Master中提取抽象（5分）
             <3>联动效应，只要执行Cat.Cryed()就可以使老鼠逃跑，主人惊醒。(3分)

     public interface Observer
     {
         void Response();     //观察者的响应，如是老鼠见到猫的反映
     }
     public interface Subject
     {
         void AimAt(Observer obs);   //针对哪些观察者，这里指猫的要扑捉的对象---老鼠
     }
     public class Mouse : Observer
     {
         private string name;
         public Mouse(string name, Subject subj)
         {           
             this.name = name;
             subj.AimAt(this);
         }
        
         public void Response()
         {
             Console.WriteLine(name + " attempt to escape!");
         }
     }
     public class Master : Observer
     {   
         public Master(Subject subj)
         {           
             subj.AimAt(this);
         }
        
         public void Response()
         {
             Console.WriteLine("Host waken!");
         }  
     }
  
     public class Cat : Subject
     {
         private ArrayList observers;
         public Cat()
         {   
             this.observers = new ArrayList();
         }
         public void AimAt(Observer obs)
         {
             this.observers.Add(obs);
         }
         public void Cry()
         {
             Console.WriteLine("Cat cryed!");
             foreach (Observer obs in this.observers)
             {
                 obs.Response();
             }
         }
     }
     class MainClass
     {       
         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();
         }
     }

//---------------------------------------------------------------------------------------------

设计方法二: 使用event -- delegate设计..
     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 Class1
     {
         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();
         }

     }