c#异步调用的几种方式

首先，我们分析一下异步处理的环境

需要在当前线程中获取返回值
不需要在当前线程中获取返回值，但是仍然需要对返回值做处理
对于第1中情况，还可以继续细分

在当前线程中启动线程T，然后继续执行当前线程中的其它任务，最后在当前线程中获取T的返回值
在当前线程中启动线程T，然后继续执行当前线程中的其它任务R1，等待T执行完成，当T执行完成后，继续执行当前线程中的其它任务R2，最后获取T的返回值
在当前线程中启动线程T，只要T在执行就执行任务R，最后获取T的返回值
下面，我将一一给出例子：

1.1 在当前线程中启动线程T，然后继续执行当前线程中的其它任务，最后在当前线程中获取T的返回值
view sourceprint?01 using System;

02 using System.Collections.Generic;

03 using System.Linq;

04 using System.Windows.Forms;

05 using System.Threading;

06 using System.Runtime.Remoting.Messaging;

07 namespace FirstWF

08 {

09     static class Program

10     {

11         /// <summary>

12         /// The main entry point for the application.

13         /// </summary>

14         [STAThread]

15         static void Main()

16         {

17             AsyncFuncDelegate caller = new AsyncFuncDelegate(Func);

18             Console.WriteLine("Input number please...");

19             IAsyncResult result = caller.BeginInvoke(Convert.ToInt32(Console.ReadLine()), null, null);

20             Console.WriteLine("Implement other tasks");

21             Thread.Sleep(7000);

22             Console.WriteLine("Implement other tasks end ...");

23             Console.WriteLine("Get user's input");

24             Console.WriteLine(caller.EndInvoke(result));

25             Console.ReadLine();

26         }

27         delegate string AsyncFuncDelegate(int userInput);

28         static string Func(int userInput)

29         {

30             Console.WriteLine("Func start to run");

31             Console.WriteLine("...");

32             Thread.Sleep(5000);

33             Console.WriteLine("Func end to run");

34             return userInput.ToString();

35         }

36     }

37 }

输出结果如下:

Implement other tasks

Func start to run

...

Func end to run

Implement other tasks end ...

Get user's input

56

1.2 在当前线程中启动线程T，然后继续执行当前线程中的其它任务R1，等待T执行完成，当T执行完成后，继续执行当前线程中的其它任务R2，最后获取T的返回值
view sourceprint?01 static void Main()

02         {

03             AsyncFuncDelegate caller = new AsyncFuncDelegate(Func);

04             Console.WriteLine("Input number please...");

05             IAsyncResult result = caller.BeginInvoke(Convert.ToInt32(Console.ReadLine()), null, null);

06             Console.WriteLine("Implement task 1");

07             result.AsyncWaitHandle.WaitOne();

08             result.AsyncWaitHandle.Close();

09             Console.WriteLine("Implment task 2");

10             Console.WriteLine("Get user's input");

11             Console.WriteLine(caller.EndInvoke(result));

12             Console.ReadLine();

13         }

输出结果如下:

Input number please...

25

Implement task 1

Func start to run

...

Func end to run

Implment task 2

Get user's input

25

1.3 在当前线程中启动线程T，只要T在执行就执行任务R，最后获取T的返回值
view sourceprint?01 [STAThread]

02         static void Main()

03         {

04             AsyncFuncDelegate caller = new AsyncFuncDelegate(Func);

05             Console.WriteLine("Input number please...");

06             IAsyncResult result = caller.BeginInvoke(Convert.ToInt32(Console.ReadLine()), null, null);

07             while (!result.IsCompleted)

08             {

09                 Thread.Sleep(1000);

10                 Console.Write(">");

11             }

12             Console.WriteLine("");

13             Console.WriteLine("Implement other task2");

14             Console.WriteLine("Get user's input");

15             Console.WriteLine(caller.EndInvoke(result));

16             Console.ReadLine();

17         }

输出结果如下:

Func start to run

...

>>>>>Func end to run

>

Implement other task2

Get user's input

23

2 不需要在当前线程中获取返回值，但是仍然需要对返回值做处理

view sourceprint?01 using System;

02 using System.Collections.Generic;

03 using System.Linq;

04 using System.Windows.Forms;

05 using System.Threading;

06 using System.Runtime.Remoting.Messaging;

07 namespace FirstWF

08 {

09     static class Program

10     {

11         /// <summary>

12         /// The main entry point for the application.

13         /// </summary>

14         [STAThread]

15         static void Main()

16         {

17             AsyncFuncDelegate caller = new AsyncFuncDelegate(Func);

18             Console.WriteLine("Input number please...");

19             caller.BeginInvoke(Convert.ToInt32(Console.ReadLine()), new AsyncCallback(CallBackFunc), "Message from Main thread.");

20             Console.WriteLine("Main thread ends");

21             Console.ReadLine();

22         }

23         delegate string AsyncFuncDelegate(int userInput);

24         static string Func(int userInput)

25         {

26             Console.WriteLine("Func start to run");

27             Console.WriteLine("...");

28             Thread.Sleep(5000);

29             Console.WriteLine("Func end to run");

30             return userInput.ToString();

31         }

32         static void CallBackFunc(IAsyncResult ar)

33         {

34             AsyncResult result = ar as AsyncResult;

35             string inputMessage = result.AsyncState as string;

36             AsyncFuncDelegate caller = result.AsyncDelegate as AsyncFuncDelegate;

37             Console.WriteLine("call back starts");

38             Console.WriteLine(inputMessage);

39             Console.WriteLine("The input number is : " + caller.EndInvoke(ar));

40             Console.WriteLine("call back ends");

41         }

42     }

43 }

输出结果如下:

Input number please...

23

Main thread ends

Func start to run

...

Func end to run

call back starts

Message from Main thread.

The input number is : 23

call back ends