猫叫，老鼠跑，主人醒（event-delegate实现）

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

namespace EventDelegate
{
    public delegate void SubEventHandle();//委托定义

    /// <summary>
    /// 发出动作的类
    /// </summary>
    public abstract class Subject
    {
        public event SubEventHandle SubEvent;//事件定义

        protected void FireAway()
        {
            if (this.SubEvent!=null)
                this.SubEvent();
        }
    }

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

    public abstract class Observer
    {
        public Observer(Subject sub)
        {
            sub.SubEvent += new SubEventHandle(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("The Mouse " + name + " attempt to escape!");
        }
    }
    
    public class Master:Observer
    {
        private string name;
        public Master(string name,Subject sub):base(sub)
        {
            this.name = name;
        }
        public override void Response()
        {
            Console.WriteLine("The Master "+name+" is wakeup!");
        }
    }

    class Program
    {
        static void Main(string[] args)
        {
            Cat cat = new Cat();
            Mouse mouse1 = new Mouse("zhan", cat);
            Mouse mouse2 = new Mouse("hua",cat);
            Master master = new Master("tao",cat);
            cat.Cry();
        }
    }
}