事件和委托的例子

 1 using System;

 2 using System.Collections.Generic;

 3 using System.Text;

 4 

 5 namespace Delegate 

 6 {

 7     // 热水器

 8     public class Heater 

 9     {

10        private int temperature;

11        public string type ="RealFire 001";       // 添加型号作为演示

12        public string area = "China Xian";         // 添加产地作为演示

13        //声明委托

14        public delegate void BoiledEventHandler(Object sender, BoiledEventArgs e);

15        public event BoiledEventHandler Boiled;//声明事件

16 

17        // 定义BoiledEventArgs类，传递给Observer所感兴趣的信息

18        public class BoiledEventArgs : EventArgs 

19        {

20            public readonly int temperature;

21            public BoiledEventArgs(int temperature) 

22            {

23               this.temperature = temperature;

24            }

25        }

26 

27        // 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

28        protected virtual void OnBoiled(BoiledEventArgs e) 

29        {

30            if (Boiled != null) 

31            { // 如果有对象注册

32               Boiled(this, e);  // 调用所有注册对象的方法

33            }

34        }

35        

36        // 烧水。

37        public void BoilWater() 

38        {

39            for (int i = 0; i <= 10; i++) 

40            {

41               temperature = i;

42               if (temperature > 5) 

43               {

44                   //建立BoiledEventArgs 对象。

45                   BoiledEventArgs e = new BoiledEventArgs(temperature);

46                   OnBoiled(e);  // 调用 OnBolied方法

47               }

48            }

49        }

50     }

51 

52     // 警报器

53     public class Alarm 

54     {

55        public void MakeAlert(Object sender, Heater.BoiledEventArgs e) 

56        {

57            Heater heater = (Heater)sender;    //这里是不是很熟悉呢？

58            //访问 sender 中的公共字段

59            Console.WriteLine("Alarm：{0} - {1}: ", heater.area, heater.type);

60            Console.WriteLine("Alarm: 嘀嘀嘀，水已经 {0} 度了：", e.temperature);

61            Console.WriteLine();

62        }

63     }

64 

65     // 显示器

66     public class Display 

67     {

68        public static void ShowMsg(Object sender, Heater.BoiledEventArgs e) 

69        {  //静态方法

70            Heater heater = (Heater)sender;

71            Console.WriteLine("Display：{0} - {1}: ", heater.area, heater.type);

72            Console.WriteLine("Display：水快烧开了，当前温度：{0}度。", e.temperature);

73            Console.WriteLine();

74        }

75     }

76 

77     class Program 

78     {

79        static void Main() 

80        {

81            Heater heater = new Heater();

82            Alarm alarm = new Alarm();

83 

84            heater.Boiled += alarm.MakeAlert;   //注册方法

85            heater.Boiled += (new Alarm()).MakeAlert;     //给匿名对象注册方法

86            heater.Boiled += new Heater.BoiledEventHandler(alarm.MakeAlert);   //也可以这么注册

87            heater.Boiled += Display.ShowMsg;       //注册静态方法

88 

89            heater.BoilWater();   //烧水，会自动调用注册过对象的方法

90            Console.ReadKey();

91        }

92     }

93 }

另一个例子

 1 using System;

 2 //步骤1：创建代理对象 

 3 public delegate void MyHandler1(object sender, MyEventArgs e);

 4 public delegate void MyHandler2(object sender, MyEventArgs e);

 5 //步骤2：创建事件处理程序方法 

 6 class A

 7 {

 8     //public const string m_id = "Class A";

 9     public void OnHandler1(object sender, MyEventArgs e)

10     {

11         Console.WriteLine("I am in OnHandler1 and MyEventArgs is {0}", e.m_id);

12     }

13     public void OnHandler2(object sender, MyEventArgs e)

14     {

15         Console.WriteLine("I am in OnHandler2 and MyEventArgs is {0}", e.m_id);

16     }

17     //步骤3：创建代理，安装事件处理程序，并向启动事件的对象注册。 

18     public A(B b)

19     {

20         MyHandler1 d1 = new MyHandler1(OnHandler1);

21         MyHandler2 d2 = new MyHandler2(OnHandler2);

22         b.Event1 += d1;

23         b.Event2 += d2;

24     }

25 }

26 //步骤4：通过代理调用封装的方法。 

27 class B

28 {

29     public event MyHandler1 Event1;

30     public event MyHandler2 Event2;

31     public void FireEvent1(MyEventArgs e)

32     {

33         if (Event1 != null)

34         {

35             Event1(this, e);

36         }

37     }

38     public void FireEvent2(MyEventArgs e)

39     {

40         if (Event2 != null)

41         {

42             Event2(this, e);

43         }

44     }

45 }

46 public class MyEventArgs : EventArgs

47 {

48     public string m_id;

49 }

50 public class Driver

51 {

52     public static void Main()

53     {

54         B b = new B();

55         A a = new A(b);

56         MyEventArgs e1 = new MyEventArgs();

57         MyEventArgs e2 = new MyEventArgs();

58         e1.m_id = "Event args for event 1";

59         e2.m_id = "Event args for event 2";

60         b.FireEvent1(e1);

61         b.FireEvent2(e2);

62         Console.ReadKey();

63     }

64 }