C#视频

 1 using System;
 2 using System.Collections.Generic;
 3 using System.Linq;
 4 using System.Text;
 5 using System.Collections;
 6 
 7 namespace ConsoleApplication1
 8 {
 9 
10     delegate void EatDelegate(string food);
11 
12     class Program
13     {
14         static void JimEat(string food)
15         {
16             Console.WriteLine("Jim eats " + food);
17         }
18         static void DavidEat(string food)
19         {
20             Console.WriteLine("David eats " + food);
21         }
22         static void TimEat(string food)
23         {
24             Console.WriteLine("Tim eats " + food);
25         }
26 
27         static void Main(string[] args)
28         {
29             EatDelegate jim = new EatDelegate(JimEat);
30             EatDelegate david = new EatDelegate(DavidEat);
31             EatDelegate tim = new EatDelegate(TimEat);
32             jim("Apple");
33             david("Apple");
34             tim("Apple");
35 
36             // 委托链
37             EatDelegate ed;
38             ed = jim + tim + david;
39 
40 
41             foreach(EatDelegate e in ed.GetInvocationList())
42             {
43                 Console.WriteLine(e.Method.Name);
44             }
45 
46             ed("apple");
47 
48             ed -= tim;
49 
50             ed("orange");
51 
52             // 匿名方法
53             EatDelegate ed1 = null;
54             ed1 += delegate (string food){ Console.WriteLine("A eats " + food);};
55             ed1 += delegate(string food) { Console.WriteLine("B eats " + food); };
56             ed1.Invoke("pineapple");
57 
58             Console.ReadLine();
59         }
60     }
61 }

View Code

委托的本职就是一个Class，任何可以声明Class的地方都可以声明委托。

 1 using System;
 2 using System.Collections.Generic;
 3 using System.Linq;
 4 using System.Text;
 5 using System.Collections;
 6 
 7 namespace ConsoleApplication1
 8 {
 9 
10     delegate void EatDelegate(string food);
11 
12     class Program
13     {
14         static void JimEat(string food)
15         {
16             Console.WriteLine("Jim eats " + food);
17         }
18         static void DavidEat(string food)
19         {
20             Console.WriteLine("David eats " + food);
21         }
22         static void TimEat(string food)
23         {
24             Console.WriteLine("Tim eats " + food);
25         }
26 
27         static void Main(string[] args)
28         {
29             EatDelegate jim = new EatDelegate(JimEat);
30             EatDelegate david = new EatDelegate(DavidEat);
31             EatDelegate tim = new EatDelegate(TimEat);
32             jim("Apple");
33             david("Apple");
34             tim("Apple");
35 
36             // 委托链
37             EatDelegate ed;
38             ed = jim + tim + david;
39 
40 
41             foreach(EatDelegate e in ed.GetInvocationList())
42             {
43                 Console.WriteLine(e.Method.Name);
44             }
45 
46             ed("apple");
47 
48             ed -= tim;
49 
50             ed("orange");
51 
52             // 匿名方法
53             EatDelegate ed1 = null;
54             ed1 += delegate (string food){ Console.WriteLine("A eats " + food);};
55             ed1 += delegate(string food) { Console.WriteLine("B eats " + food); };
56             ed1.Invoke("pineapple");
57 
58             Console.ReadLine();
59         }
60     }
61 }

View Code

委托链，可以通过GetInvocationList（）获取委托链中的每个委托元素，进而获取每个元素的方法名称，返回值类型等。

还可以通过delegate声明匿名函数。

 1 using System;
 2 using System.Collections.Generic;
 3 using System.Linq;
 4 using System.Text;
 5 using System.Collections;
 6 
 7 namespace ConsoleApplication1
 8 {
 9 
10     delegate void EatDelegate(string food);
11 
12     class Man
13     {
14         private string name;
15 
16         public Man(string name)
17         {
18             this.name = name;
19         }
20 
21         public void eat(string food)
22         {
23             Console.WriteLine("{0} eats {1}", name, food);
24         }
25     }
26 
27     class Program
28     {
29 
30         static void eatTogether(string food, params EatDelegate[] values)
31         {
32             if (values == null)
33             {
34                 Console.WriteLine("Party is over.");
35             }
36             else
37             {
38                 EatDelegate ed = null;
39                 foreach(EatDelegate e in values)
40                 {
41                     ed += e;
42                 }
43 
44                 ed(food);
45                 Console.WriteLine();
46             }
47         }
48 
49         static void Main(string[] args)
50         {
51             Man jim = new Man("Jim");
52             Man david = new Man("David");
53             Man tim = new Man("Tim");
54             Man jun = new Man("Jun");
55 
56             // 动态方法
57             EatDelegate jimED = new EatDelegate(jim.eat);
58             EatDelegate davidED = new EatDelegate(david.eat);
59             EatDelegate timED = new EatDelegate(tim.eat);
60             EatDelegate junED = new EatDelegate(jun.eat);
61 
62             EatDelegate ed = null;
63             ed = jimED + davidED + timED + junED;
64             ed("orange");
65 
66             eatTogether("pig", davidED, jimED, junED);
67 
68             eatTogether("egg", timED, davidED);
69 
70             eatTogether(null, null);
71 
72             Console.ReadLine();
73         }
74     }
75 }

View Code

Note：动态方法。