public class People
    {
        string name;
        public People(string name)
        {
            this.name = name;
        }

        public void Getup()
        {
            Console.WriteLine("猫来了,{0}醒了", name);
        }
    }

    class Mouse
    {
        private string name;

        public Mouse(string name)
        {
            this.name = name;
        }

        public void Run()
        {
            Console.WriteLine("猫来了,{0},跑", name);
        }
    }

    class Cat
    {
        private string name;
        public Cat(string name)
        {
            this.name = name;
        }

        public delegate void CatShoutEventHandler();

        public event CatShoutEventHandler CatShout;

        public void Shout()
        {
            Console.WriteLine("喵，我是:{0}", name);

            if (CatShout != null)
            {
                CatShout();
            }
        }
    }

class Program
    {
        static void Main(string[] args)
        {
            Cat cat = new Cat("Tom");
            Mouse mouse1 = new Mouse("Jerrry");
            Mouse mouse2 = new Mouse("Jack");
            People people = new People("Owner");

            cat.CatShout += new Cat.CatShoutEventHandler(mouse1.Run);
            cat.CatShout += new Cat.CatShoutEventHandler(mouse2.Run);
            cat.CatShout += new Cat.CatShoutEventHandler(people.Getup);

            cat.CatShout -= new Cat.CatShoutEventHandler(mouse2.Run);


            cat.Shout();

            Console.Read();
        }
    }

//Subject接口
    public abstract class Subject
    {
        private ArrayList observerList = new ArrayList();

        public void Attach(Observer observer)
        { 
            observerList.Add(observer); 
        }

        public void Detach(Observer observer)
        {
            observerList.Remove(observer); 
        }

        public void Notify()
        {
            foreach (Observer item in observerList)
            {
                item.Update();
            }
        }
    }
    public class Cat : Subject
    {
        private string catstate;
        public string CatState
        {
            get { return catstate; }
            set { catstate = value; }
        }
    }

//Observer接口
    public interface Observer
    {
        void Update();
}

//具体的Observer
    public class Mouse : Observer
    {
        private Cat cat;

        public Mouse(Cat cat)
        {
            this.cat = cat;
        }
        public void Update()
        {
            if (this.cat.CatState == "cry")
            {
                Console.WriteLine("The cat cry, and the Mouse run!" );
            }
        }
    }
    public class Human : Observer
    {
        private Cat cat;

        public Human(Cat cat)
        {
            this.cat = cat;
        }
        public void Update()
        {
            if (this.cat.CatState == "cry")
            {
                Console.WriteLine("The cat cry, and the Human wake!");
            }
        }
}

//系统开始运行
    class Program
    {
        static void Main(string[] args)
        {
            Cat cat = new Cat();
            cat.Attach(new Mouse(cat));
            cat.Attach(new Human(cat));

            cat.CatState = "cry";
            cat.Notify();
        }
    }

View Code 

using System;
using System.Collections.Generic;
using System.Text;

namespace 观察者模式
{
    class Program
    {
        static void Main(string[] args)
        {
            //老板胡汉三
            Boss huhansan = new Boss();

            //看股票的同事
            StockObserver tongshi1 = new StockObserver("魏关姹", huhansan);
            //看NBA的同事
            NBAObserver tongshi2 = new NBAObserver("易管查", huhansan);

            huhansan.Update += new EventHandler(tongshi1.CloseStockMarket);
            huhansan.Update += new EventHandler(tongshi2.CloseNBADirectSeeding);

            //老板回来
            huhansan.SubjectState = "我胡汉三回来了！";
            //发出通知
            huhansan.Notify();

            Console.Read();


        }
    }

    //通知者接口
    interface Subject
    {
        void Notify();
        string SubjectState
        {
            get;
            set;
        }
    }

    //事件处理程序的委托
    delegate void EventHandler();

    class Secretary : Subject
    {
        //声明一事件Update，类型为委托EventHandler
        public event EventHandler Update;

        private string action;

        public void Notify()
        {
            Update();
        }
        public string SubjectState
        {
            get { return action; }
            set { action = value; }
        }
    }

    class Boss : Subject
    {
        //声明一事件Update，类型为委托EventHandler
        public event EventHandler Update;

        private string action;

        public void Notify()
        {
            Update();
        }
        public string SubjectState
        {
            get { return action; }
            set { action = value; }
        }
    }

    //看股票的同事
    class StockObserver
    {
        private string name;
        private Subject sub;
        public StockObserver(string name, Subject sub)
        {
            this.name = name;
            this.sub = sub;
        }

        //关闭股票行情
        public void CloseStockMarket()
        {
            Console.WriteLine("{0} {1} 关闭股票行情，继续工作！", sub.SubjectState, name);
        }
    }

    //看NBA的同事
    class NBAObserver
    {
        private string name;
        private Subject sub;
        public NBAObserver(string name, Subject sub)
        {
            this.name = name;
            this.sub = sub;
        }

        //关闭NBA直播
        public void CloseNBADirectSeeding()
        {
            Console.WriteLine("{0} {1} 关闭NBA直播，继续工作！", sub.SubjectState, name);
        }
    }
}