Delegate&Event

Posted 2020-08-15

Delegate

1.基本类：

 1     public class Student
 2     {
 3         public int Id { get; set; }
 4         public string Name { get; set; }
 5 
 6         public void Study()
 7         {
 8             Console.WriteLine("学习.net高级班公开课");
 9         }
10 
11         public void StudyAdvanced(string name)
12         {
13             Console.WriteLine("学习.net高级班公开课");
14         }
15 
16         public static void Show()
17         {
18             Console.WriteLine("123");
19         }
20     }

Student

2. 声明委托

1         public delegate void NoReturnNoPara();
2         public delegate void NoReturnWithPara(int x, int y);
3         public delegate int WithReturnNoPara();
4         public delegate string WithReturnWithPara(int x, int y);    

3. =+ 的方法

 1         private void DoNothing()
 2         {
 3             Console.WriteLine("这里是DoNothing");
 4         }
 5 
 6         private static void DoNothingStatic()
 7         {
 8             Console.WriteLine("这里是DoNothing");
 9         }
10 
11         private void ShowPlus(int x, int y)
12         {
13             Console.WriteLine("ShowPlus x={0} y={1} x+y={2}", x, y, x + y);
14         }
15 
16         private static void ShowPlusStatic(int x, int y)
17         {
18             Console.WriteLine("ShowPlusStatic x={0} y={1} x+y={2}", x, y, x + y);
19         }    

4.委托三部曲

声明(在上面)+实例化+调用

1            {
2                 NoReturnNoPara method = new NoReturnNoPara(this.DoNothing);//2 委托的实例化
3                 method.Invoke();//3 委托调用
4                 method();//另一种调用方式
5                 //method.BeginInvoke(null, null);//异步调用
6                 this.DoNothing();//直接调用对应的方法，效果一样
7             }    

5.多播委托

 1          {
 2                 NoReturnNoPara method = new NoReturnNoPara(MyDelegate.DoNothingStatic);
 3                 method += student.Study;
 4                 method -= student2.Study;
 5                 method += this.DoNothing;
 6                 method += student.Study;
 7                 method += Student.Show;
 8                 method += () => Console.WriteLine("这里lambda");
 9                 method.Invoke();
10                 //method.BeginInvoke(null,null);//多播委托不能异步
11                 method -= MyDelegate.DoNothingStatic;
12                 method -= MyDelegate.DoNothingStatic;
13                 method -= this.DoNothing;
14                 method -= student.Study;
15                 method -= Student.Show;
16                 method -= () => Console.WriteLine("这里lambda");
17 
18                 //委托里面lambda表达式之后加入的方法都无效了？
19                 method.Invoke();
20             }
21             {
22                 NoReturnNoPara method = new NoReturnNoPara(student.Study);
23                 method.Invoke();
24             }
25             {
26                 NoReturnNoPara method = new NoReturnNoPara(Student.Show);
27                 method.Invoke();
28             }
29             {
30                 NoReturnWithPara method = new NoReturnWithPara(ShowPlus);
31                 method += ShowPlus;
32                 method += ShowPlus;
33                 method += ShowPlus;
34                 method -= ShowPlus;
35                 method -= ShowPlus;
36                 method(1, 2);
37             }    

Event

1    public class Baby
2     {
3         public void Cry()
4         {
5             Console.WriteLine("{0} Cry", this.GetType().Name);
6         }
7     }

Baby

1      public class Brother
2     {
3         public void Turn()
4         {
5             Console.WriteLine("{0} Turn", this.GetType().Name);
6         }
7     }

Brother

1     public class Dog
2     {
3         public void Wang()
4         {
5             Console.WriteLine("{0} Wang", this.GetType().Name);
6         }
7     }

Dog

1     public class Father
2     {
3         public void Shout()
4         {
5             Console.WriteLine("{0} Shout", this.GetType().Name);
6         }
7     }

Father

1     public class Mother
2     {
3         public void Wispher()
4         {
5             Console.WriteLine("{0} Wispher", this.GetType().Name);
6         }
7     }

Mother

1     public class Mouse
2     {
3         public void Run()
4         {
5             Console.WriteLine("{0} Run", this.GetType().Name);
6         }
7     }

Mouse

1     public class Neighbor
2     {
3         public void Awake()
4         {
5             Console.WriteLine("{0} Awake", this.GetType().Name);
6         }
7     }

Neighbor

1     public class Stealer
2     {
3         public void Hide()
4         {
5             Console.WriteLine("{0} Hide", this.GetType().Name);
6         }
7     }

Stealer

　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　发布

 1     /// <summary>
 2     /// 发布者
 3     /// 一只猫，miao一声
 4     /// 导致一系列的触发动作
 5     /// </summary>
 6     public class Cat
 7     {
 8         public void Miao()
 9         {
10             Console.WriteLine("{0} Miao", this.GetType().Name);
11             new Neighbor().Awake();
12             new Mouse().Run();
13             new Dog().Wang();
14             new Baby().Cry();
15             new Mother().Wispher();
16             new Brother().Turn();
17             new Father().Shout();
18         }
19 
20         public Action MiaoAction;//委托的实例
21         public event Action MiaoActionEvent;//事件是 委托的实例，加了event关键字-----发布者
22         //event做了权限控制，保证外部不能赋值和调用
23         public void MiaoDelegate()
24         {
25             Console.WriteLine("{0} MiaoDelegate", this.GetType().Name);
26 
27             MiaoAction.Invoke();
28         }
29 
30         public void MiaoEvent()
31         {
32             Console.WriteLine("{0} MiaoEvent", this.GetType().Name);
33             if (MiaoActionEvent != null)
34             {
35                 //MiaoActionEvent.Invoke();
36                 //MiaoActionEvent();
37                 foreach (Action item in MiaoActionEvent.GetInvocationList())//触发
38                 {
39                     Console.WriteLine("*********");
40                     item.Invoke();
41                     //item.BeginInvoke(null,null);
42                 }
43             }
44         }
45     }

订阅:

 1 　　　　　　　　　　{
 2                     Console.WriteLine("*******Miao******");
 3                     Cat cat = new Cat();
 4                     cat.Miao();
 5 
 6                     Console.WriteLine("*******MiaoDelegate******");
 7                     //cat.MiaoAction += new Neighbor().Awake;
 8 
 9                     cat.MiaoAction += new Mouse().Run;
10                     cat.MiaoAction -= new Mouse().Run;
11                     cat.MiaoAction += new Baby().Cry;
12                     cat.MiaoAction += new Mother().Wispher;
13 
14                     cat.MiaoAction.Invoke();
15                     cat.MiaoAction = null;
16 
17                     cat.MiaoAction += new Brother().Turn;
18                     cat.MiaoAction += new Father().Shout;
19                     cat.MiaoAction += new Dog().Wang;
20                     
21                     cat.MiaoDelegate();
22 
23                     Console.WriteLine("*******MiaoEvent******");
24                     cat.MiaoActionEvent += new Neighbor().Awake;
25                     cat.MiaoActionEvent += new Mouse().Run;
26                     cat.MiaoActionEvent += new Baby().Cry;
27 
28                     //cat.MiaoActionEvent.Invoke();
29                     //cat.MiaoActionEvent = null;
30 
31                     cat.MiaoActionEvent += new Mother().Wispher;
32                     cat.MiaoActionEvent += new Brother().Turn;
33                     cat.MiaoActionEvent += new Father().Shout;
34                     cat.MiaoActionEvent += new Dog().Wang;
35                     cat.MiaoEvent();
36                 }