在编辑显然不需要调用的控件时异常

本文关键字：控件 异常 调用 不需要 编辑 | 更新日期: 2023-09-27 18:17:35

我试图从另一个线程更改控件的Text属性。我使用这个方法来做这件事:

        public static void InvokeIfRequired(this Control control, MethodInvoker action)
        {
            if (control.InvokeRequired)
            {
                try
                {
                    control.Invoke(action);
                }
                catch (ObjectDisposedException) { }
                catch (InvalidAsynchronousStateException) { }
            }
            else
            {
                action();
            }
        }

使用此方法时，我仍然得到'System.InvalidOperationException'异常。当我闯入这个，我可以看到control.InvokeRequired是false，但它看起来像它实际上是从另一个线程访问??

在实际的错误消息中，它没有给我提供我试图调用的相同的控件。相反，它给出了控件驻留的形式，说明'Form1 accessed from a thread other than the thread it was created on'.

我尝试将表单传递给InvokeIfRequired方法，但仍然Form1.InvokeRequired是false，异常发生。我试图调用的控件已在设计器中创建。

下面是我用来编辑控件的代码:

        private void StartUpdateThreads()  // called from the Form ctor
        {
            new Thread(new ThreadStart(this.TimeUpdater)).Start();
            new Thread(new ThreadStart(this.AccountBalanceUpdater)).Start();
        }
        private void TimeUpdater()
        {
            while (!this.IsDisposed)
            {
                Utilities.InvokeIfRequired(this, (MethodInvoker)(() =>
                    {
                        this.timestampLabel.Text = DateTime.Now.ToString("dd/MM/yyyy HH:mm:ss");
                    }));
                Thread.Sleep(250);
            }
        }

下面是调用栈:

    MyApp.exe!MyApp.MyAppToolbar.TimeUpdater.AnonymousMethod__0() Line 133 + 0x41 bytes 
    MyApp.exe!MyApp.Utilities.InvokeIfRequired(System.Windows.Forms.Control control, System.Windows.Forms.MethodInvoker action) Line 34 + 0xb bytes 
    MyApp.exe!MyApp.MyAppToolbar.TimeUpdater() Line 131 + 0x49 bytes

下面是堆栈跟踪:

    at System.Windows.Forms.Control.get_Handle()'r'n   
    at System.Windows.Forms.Control.get_InternalHandle()'r'n   
    at System.Windows.Forms.Control.get_CreateParams()'r'n   
    at System.Windows.Forms.Label.get_CreateParams()'r'n   
    at System.Windows.Forms.Control.SizeFromClientSize(Int32 width, Int32 height)'r'n   
    at System.Windows.Forms.Control.SizeFromClientSize(Size clientSize)'r'n   
    at System.Windows.Forms.Label.GetBordersAndPadding()'r'n   
    at System.Windows.Forms.Label.GetPreferredSizeCore(Size proposedConstraints)'r'n   
    at System.Windows.Forms.Control.GetPreferredSize(Size proposedSize)'r'n   
    at System.Windows.Forms.Label.GetPreferredSize(Size proposedSize)'r'n   
    at System.Windows.Forms.Control.get_PreferredSize()'r'n   
    at System.Windows.Forms.Label.AdjustSize()'r'n   
    at System.Windows.Forms.Label.OnTextChanged(EventArgs e)'r'n   
    at System.Windows.Forms.Control.set_Text(String value)'r'n   
    at System.Windows.Forms.Label.set_Text(String value)'r'n   
    at MyApp.MyAppToolbar.<TimeUpdater>b__0() in PATH''TO''FILE.cs:line 133'r'n   
    at MyApp.Utilities.InvokeIfRequired(Control control, MethodInvoker action) in PATH''TO''FILE.cs:line 34'r'n  MyApp.MyAppToolbar.TimeUpdater() in PATH''TO''FILE.cs:line 131'r'n   
    at System.Threading.ThreadHelper.ThreadStart_Context(Object state)'r'n   
    at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)'r'n   
    at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)'r'n   
    at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)'r'n   
    at System.Threading.ThreadHelper.ThreadStart()

谁能给我指一下正确的方向?

在编辑显然不需要调用的控件时异常

阅读InvokeRequired的文档，您可以看到当控件的句柄尚未创建时，它返回false。

检查IsHandleCreated的值。

还有一个关于销毁时间的问题，正如Hans上面所说的，所以当在正确的线程中时，您可能想要检查控件是否已经被处置。

另一种方法是在控件完全加载时启动后台线程，但这再次使InvokeIfRequired不是一个通用工具。

夏洛克，我想这会对你有帮助http://msdn.microsoft.com/en-us/library/ms171728 (v = vs.80) . aspx

相关文章：