与UI交谈的线程？

Question

我有这样的代码：

private void buttonStart_Click(object sender, EventArgs e) 
{ 
    Task.Factory.StartNew(() => GeneraListaCartelle()) 
     .ContinueWith(t => GeneraListaCartelleCompletata() 
     , CancellationToken.None 
     , TaskContinuationOptions.None 
     , TaskScheduler.FromCurrentSynchronizationContext()); 
} 

private void GeneraListaCartelle() 
{ 
    try 
    { 
     ... some operation .... 
    } 
    catch (Exception err) 
    { 
     txtErrors.AppendText(err.Message); 
    } 
} 

GeneraListaCartelleCompletata() 
{ 
    ... process finished... 
} 

和txtErrors是 “主” 线程（UI）。当我发现错误时，异步线程无法写入UI控件，并且我得到一个invalid cross-thread exception。

我可以使用线程内的UI进行对话吗？

Answer 1

如果你是靶向然后WinForm应用程序：

try 
    { 
     ... some operation .... 
    } 
catch (Exception err) 
    { 
     if (txtErrors.InvokeRequired) 
     { 
      txtErrors.BeginInvoke(new MethodInvoker(
       delegate { txtErrors.AppendText(err.Message); }) 
       ); 
     } 
    } 

Answer 2

如果您正在使用的WinForms，你将需要调用你的方法在UI线程像

catch (Exception err) 
{ 
    if(this.InvokeRequired){ 
     Action<Exception> act = ((ex) => { 
      txtErrors.AppendText(ex.Message); 
     }); 
     this.Invoke(act, new object[] { err }); 
    } 
    else{ 
     txtErrors.AppendText(err.Message); 
    } 
} 

如果您正在使用WPF你将需要

catch (Exception err) 
{ 
    if(this.Dispatcher.CheckAccess()){ 
     txtErrors.AppendText(err.Message); 
    } 
    else { 
      Action<Exception> act = ((ex) => { 
      txtErrors.AppendText(ex.Message); 
      }); 
     this.Dispatcher.Invoke(act, new object[] { err }); 
    } 
} 

Answer 3

有来自msdn一个例子：

// This delegate enables asynchronous calls for setting 
// the text property on a TextBox control. 
delegate void SetTextCallback(string text); 

// This method demonstrates a pattern for making thread-safe 
// calls on a Windows Forms control. 
// 
// If the calling thread is different from the thread that 
// created the TextBox control, this method creates a 
// SetTextCallback and calls itself asynchronously using the 
// Invoke method. 
// 
// If the calling thread is the same as the thread that created 
// the TextBox control, the Text property is set directly. 
private void SetText(string text) 
{ 
    // InvokeRequired required compares the thread ID of the 
    // calling thread to the thread ID of the creating thread. 
    // If these threads are different, it returns true. 
    if (this.textBox1.InvokeRequired) 
    { 
     SetTextCallback d = new SetTextCallback(SetText); 
     this.Invoke(d, new object[] { text }); 
    } 
    else 
    { 
     this.textBox1.Text = text; 
    } 
} 

Answer 4

集CheckForIllegalCrossThreadCalls假的叫Form_Load事件处理程序

Answer 5

拉这一个老项目，我不得不处理从另一个线程更新UI的。也应该为你工作。

delegate void addtoValProg(); 
addtoValProg myDelegate; 

myDelegate = new addtoValProg(invokeControl); 

private void GeneraListaCartelle() 
{ 
    try 
    { 
     //... some operation .... 
    } 
    catch (Exception err) 
    { 
     invokeControl(); 
    } 
} 

private void invokeControl() 
{ 
    if (this.InvokeRequired) 
    { 
     this.Invoke(this.myDelegate); 
    } 
    else 
    { 
     txtErrors.AppendText(err.Message); 
     txtErrors.Update(); 
    } 
}