观察者模式

class Program    {        static void Main(string[] args)        {            ConcreteSubject s = new ConcreteSubject();            s.Attach(new ConcreteObserver(s, "X"));            s.Attach(new ConcreteObserver(s, "Y"));            s.Attach(new ConcreteObserver(s, "Z"));            s.SubjectState = "ABC";            s.Notify();            Console.Read();        }    }    abstract class Subject    {        private IList
     
       observers = new List
      
       ();        //增加观察者        public void Attach(Observer observer)        {            observers.Add(observer);        }        //移除观察者        public void Detach(Observer observer)        {            observers.Remove(observer);        }        //通知        public void Notify()        {            foreach (Observer o in observers)            {                o.Update();            }        }    }    //具体通知者    class ConcreteSubject : Subject    {        private string subjectState;        //具体通知者状态        public string SubjectState        {            get { return subjectState; }            set { subjectState = value; }        }    }    abstract class Observer    {        public abstract void Update();    }    class ConcreteObserver : Observer    {        private string name;        private string observerState;        private ConcreteSubject subject;        public ConcreteObserver(          ConcreteSubject subject, string name)        {            this.subject = subject;            this.name = name;        }        //更新        public override void Update()        {            observerState = subject.SubjectState;            Console.WriteLine("观察者{0}的新状态是{1}",              name, observerState);        }        public ConcreteSubject Subject        {            get { return subject; }            set { subject = value; }        }    }
      
     

烧水事件

// 热水器    public class Heater    {        private int temperature;        public string type = "RealFire 001";              // 添加型号作为演示        public string area = "China Xian";                     // 添加产地作为演示        //声明委托        public delegate void BoiledEventHandler(Object sender, BoliedEventArgs e);        public event BoiledEventHandler Boiled;       //声明事件        // 定义BoliedEventArgs类，传递给Observer所感兴趣的信息        public class BoliedEventArgs : EventArgs        {            public readonly int temperature;            public BoliedEventArgs(int temperature)            {                this.temperature = temperature;            }        }        // 可以供继承自 Heater 的类重写，以便继承类拒绝其他对象对它的监视        protected virtual void OnBolied(BoliedEventArgs e)        {            if (Boiled != null)            {       // 如果有对象注册                Boiled(this, e);       // 调用所有注册对象的方法            }        }        // 烧水。        public void BoilWater()        {            for (int i = 0; i <= 100; i++)            {                temperature = i;                if (temperature > 95)                {                    //建立BoliedEventArgs 对象。                    BoliedEventArgs e = new BoliedEventArgs(temperature);                    OnBolied(e);       // 调用 OnBolied方法                }            }        }    }    // 警报器    public class Alarm    {        public void MakeAlert(Object sender, Heater.BoliedEventArgs e)        {            Heater heater = (Heater)sender;              //这里是不是很熟悉呢？            //访问 sender 中的公共字段            Console.WriteLine("Alarm：{0} - {1}: ", heater.area, heater.type);            Console.WriteLine("Alarm: 嘀嘀嘀，水已经 {0} 度了：", e.temperature);            Console.WriteLine();        }    }    // 显示器    public class Display    {        public static void ShowMsg(Object sender, Heater.BoliedEventArgs e)        {       //静态方法            Heater heater = (Heater)sender;            Console.WriteLine("Display：{0} - {1}: ", heater.area, heater.type);            Console.WriteLine("Display：水快烧开了，当前温度：{0}度。", e.temperature);            Console.WriteLine();        }    }    class Program    {        static void Main()        {            Heater heater = new Heater();            Alarm alarm = new Alarm();            heater.Boiled += alarm.MakeAlert;       //注册方法            heater.Boiled += (new Alarm()).MakeAlert;              //给匿名对象注册方法            heater.Boiled += new Heater.BoiledEventHandler(alarm.MakeAlert);       //也可以这么注册            heater.Boiled += Display.ShowMsg;              //注册静态方法            heater.BoilWater();       //烧水，会自动调用注册过对象的方法            Console.Read();        }    }

猫叫事件

http://www.tracefact.net/Design-Pattern/Observer.aspx