问题:猫一叫喊 所有的老鼠都逃跑

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
评分标准: <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();
        }

    }

//中国移动的例子

namespace ConsoleApplication1
{
    public interface IObserver
    {
        void Reply();        }

    public interface ISub
    {
        void AddIn(IObserver ob);
    }

    public class user : IObserver
    {
        private string no;

        public string No { get { return no; } }
        //构造时被加入到chinamobile
        public user(string no, ISub sub)
        {
            this.no = no;
            //add in
            sub.AddIn(this);
        }

        public void Reply()
        {
            Console.WriteLine(this.no + " reply");
        }
    }

    public class chinamobile:ISub
    {
        private ArrayList list = new ArrayList();

        public void AddIn(IObserver ob)
        {
            list.Add(ob);
        }

        public void send()
        {
            foreach (IObserver i in list)
            {
                //Console.WriteLine("Send to :" + i.No);
                i.Reply();
            }
        }
    }   
    class MainClass
    {
        static void Main(string[] args)
        {
            chinamobile cm = new chinamobile();
            user u1 = new user("111", cm);
            user u2 = new user("222", cm);
            user u3 = new user("333", cm);
            cm.send();
        }
    }
   

 

}