标准的C#观察者（observer）模式

using System;  
using System.Collections.Generic;  
using System.Text;  
 
namespace Delegate {  
       // 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  
              }  
       }  
}  
 
Www_  
   
 
输出为：  
 
以下为引用的内容：  
Alarm：China Xian - RealFire 001:  
Alarm: 嘀嘀嘀，水已经 96 度了：  
Alarm：China Xian - RealFire 001:  
Alarm: 嘀嘀嘀，水已经 96 度了：  
Alarm：China Xian - RealFire 001:  
Alarm: 嘀嘀嘀，水已经 96 度了：  
Display：China Xian - RealFire 001:  
Display：水快烧开了，当前温度：96度。