C# 事件和委托

 1 public class Heater {
 2        private int temperature;
 3        public string type = "RealFire 001";       // 添加型号作为演示
 4        public string area = "China Xian";         // 添加产地作为演示
 5        //声明委托
 6        public delegate void BoiledEventHandler(Object sender, BoiledEventArgs e);
 7        public event BoiledEventHandler Boiled; //声明事件
 8 
 9        // 定义BoiledEventArgs类，传递给Observer所感兴趣的信息
10        public class BoiledEventArgs : EventArgs {
11            public readonly int temperature;
12            public BoiledEventArgs(int temperature) {
13               this.temperature = temperature;
14            }
15        }
16 
17        // 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
18        protected virtual void OnBoiled(BoiledEventArgs e) {
19            if (Boiled != null) { // 如果有对象注册
20               Boiled(this, e);  // 调用所有注册对象的方法
21            }
22        }
23        
24        // 烧水。
25        public void BoilWater() {
26            for (int i = 0; i <= 100; i++) {
27               temperature = i;
28               if (temperature > 95) {
29                   //建立BoiledEventArgs 对象。
30                   BoiledEventArgs e = new BoiledEventArgs(temperature);
31                   OnBoiled(e);  // 调用 OnBolied方法
32               }
33            }
34        }
35     }
36 
37     // 警报器
38     public class Alarm {
39        public void MakeAlert(Object sender, Heater.BoiledEventArgs e) {
40            Heater heater = (Heater)sender;     //这里是不是很熟悉呢？
41            //访问 sender 中的公共字段
42            Console.WriteLine("Alarm：{0} - {1}: ", heater.area, heater.type);
43            Console.WriteLine("Alarm: 嘀嘀嘀，水已经 {0} 度了：", e.temperature);
44            Console.WriteLine();
45        }
46     }
47 
48     // 显示器
49     public class Display {
50        public static void ShowMsg(Object sender, Heater.BoiledEventArgs e) {   //静态方法
51            Heater heater = (Heater)sender;
52            Console.WriteLine("Display：{0} - {1}: ", heater.area, heater.type);
53            Console.WriteLine("Display：水快烧开了，当前温度：{0}度。", e.temperature);
54            Console.WriteLine();
55        }
56     }