WinForm中多线程操作控件

在WinForm中的多线程中，操作控件时，会报无效操作异常，解决方法是调用System.Windows.Form.Control中BeginInvoke。

代码如下：
Code

1 /// <summary>

2 /// Operate WinForm Control In Theard.

3 /// <remarks>author PetterLiu http://wintersun.cnblogs.com</remarks>
4 /// </summary>

5 public partial class ThreadFormTest : Form

6 {

7 private Thread thread;

8 private delegate void SetButtonText();

9 private delegate void SetButtonWithNewText(string txt);

10

11 public ThreadFormTest()

12 {

13 InitializeComponent();

14 }

15

16 public void ChangeButtonText()

17 {

18 MessageBox.Show(Thread.CurrentThread.ManagedThreadId.ToString());

19 this.button1.Text = DateTime.Now.ToLongTimeString();

20 }

21

22 public void ChangeButtonText2()

23 {

24 MessageBox.Show(Thread.CurrentThread.ManagedThreadId.ToString());

25 SetButtonText setbuttontext = new SetButtonText(ChangeButtonText);

26 this.button1.BeginInvoke(setbuttontext);

27 }

28

29 public void ChangeButtonWithNText()

30 {

31 MessageBox.Show(Thread.CurrentThread.ManagedThreadId.ToString());

32 SetButtonWithNewText setbuttontext = new SetButtonWithNewText(CHKNASD);

33 this.button1.BeginInvoke(setbuttontext, new object[] { "It's deliver value." });

34 }

35

36 private void CHKNASD(string txt)

37 {

38 this.button1.Text = txt;

39 }

40

41 private void button1_Click(object sender, EventArgs e)

42 {

43 thread = new Thread(new ThreadStart(ChangeButtonText));

44 thread.Start();

45 //thow InvaildOperationException

46 }

47

48 private void button2_Click(object sender, EventArgs e)

49 {

50 thread = new Thread(new ThreadStart(ChangeButtonText2));

51 thread.Start();

52 }

53

54 private void button3_Click(object sender, EventArgs e)

55 {

56 //implement deliver value.

57 thread = new Thread(new ThreadStart(ChangeButtonWithNText));

58 thread.Start();

59 }

60 }

再看《CLR.via.C#.Second.Edition.Feb.2006》中是这么说，这下清楚了。

In Windows, a window is always created by a thread, and this thread must be used to process

all actions for the window. One reason for this is because 16-bit Windows versions were sin-

gle-threaded operating systems, and in order to maintain backward compatibility, 32-bit and 64-

bit versions of Windows kept the single-threaded architecture for handling window opera-

tions such as WM_MOVE, WM_SIZE, WM_PAINT, WM_CLOSE, etc. It's common for a Windows Forms

application to use the asynchronous techniques explained in this chapter. However, since Win-

dows Forms is built on top of Windows, a thread pool thread is not allowed to directly manipu-

late a window; or more specifically, a class derived from System.Windows.Forms.Control.

Fortunately, the System.Windows.Forms.Control class offers three methods—Invoke, Begin-

Invoke, and EndInvoke-that you can call from any thread (including a thread pool thread) to

marshal an operation from the calling thread to the thread that created the window. Inter-

nally, Control's Invoke method calls the Win32 SendMessage method to have the window's

thread execute a task synchronously. Control's BeginInvoke method internally calls the

Win32 PostMessage method to have the window's thread execute a task asynchronously. If

the calling thread wants to know when the window's thread has completed executing the

task, it can call Control's EndInvoke method. If you don't care, this is one of the rare cases

when you do not have to call an EndInvoke method.