Delegate学习笔记

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, BoiledEventArgs e);
       public event BoiledEventHandler Boiled; //声明事件

       // 定义BoiledEventArgs类，传递给Observer所感兴趣的信息
       public class BoiledEventArgs : EventArgs {
           public readonly int temperature;
           public BoiledEventArgs(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 OnBoiled(BoiledEventArgs 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BoiledEventArgs 对象。
                  BoiledEventArgs e = new BoiledEventArgs(temperature);
                  OnBoiled(e);  // 调用 OnBolied方法
              }
           }
       }
    }

    // 警报器
    public class Alarm {
       public void MakeAlert(Object sender, Heater.BoiledEventArgs 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.BoiledEventArgs 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
       }
    }
}

输出为：
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。
// 省略 ...

转自:http://www.cnblogs.com/JimmyZhang/archive/2007/09/23/903360.html