Question

在我的Windows窗体应用程序中，我有一个textbox和backgroundworker组件。在dowork的{{1}}事件中，我正在尝试访问文本框的值。我怎样才能做到这一点？当我尝试访问文本框的值时，我在dowork事件处理程序代码中遇到异常：

backgroundworker

Answer 1

您只能访问 GUI线程中的textbox / form controls，您可以这样做。

if(txtFolderName.InvokeRequired)
{
    txtFolderName.Invoke(new MethodInvoker(delegate { name = txtFolderName.text; }));
}

Answer 2

您需要使用MethodInvoker。像：

BackgroundWorker worker = new BackgroundWorker();
worker.DoWork += delegate(object sender, DoWorkEventArgs e)
 {
       MethodInvoker mi = delegate { txtFolderName.Text = "New Text"; };
       if(this.InvokeRequired)
           this.Invoke(mi);
 };

Answer 3

试试这个

  txtFolderName.Invoke((MethodInvoker)delegate
            {
                string strFolderName = txtFolderName.Text;
            });

Answer 4

您必须在主线程上调用TextBox。

tb.Invoke((MethodInvoker) delegate
{
    tb.Text = "Update your text";
});

Answer 5

试试这个：

void DoWork(...)
{
    YourMethod();
}

void YourMethod()
{
    if(yourControl.InvokeRequired)
        yourControl.Invoke((Action)(() => YourMethod()));
    else
    {
        //Access controls
    }
}

希望这个帮助。

Answer 6

这是我使用的另外两种方法。

    //save the text value of txtFolderName into a local variable before run the backgroundworker. 
    string strFolderName;
    private void btnExe_Click(object sender, EventArgs e)
    {
        strFolderName = txtFolderName.text;
        backgroundworker.RunWorkerAsync();
    }

    private void backgroundworker_DoWork(object sender, DoWorkEventArgs e)
    {
        backgroundworkerMethod(strFolderName);//get the value from strFolderName
        ...
    }

    ----------------------------------------------------
    private void btnExe_Click(object sender, EventArgs e)
    {
        backgroundworker.RunWorkerAsync(txtFolderName.text);//pass the value into backgroundworker as parameter/argument
    }

    private void backgroundworker_DoWork(object sender, DoWorkEventArgs e)
    {
        backgroundworkerMethod(e.Argument.ToString());//get the value from event argument
        ...
    }

C＃在backgroundworker dowork事件中获取Textbox值

6 个答案: