Question

我正在使用Backgroundworker在处理过程中显示加载程序。但是加载程序（Progressbar）不会更新，只会在完成后更新。每当调用worker ProgressChanged事件时，它都不会更新进度条标签的值。这可能是由于异步行为导致的ProgressChanged事件。我是线程新手，请帮助。

 void  worker_DoWork(object sender, DoWorkEventArgs e)
 {


        bool isCompletedSuccessfully = true;
        FileSQLHelper objSqlHelper = new FileSQLHelper();
        PGPUtil utilityObj = new PGPUtil();


            #region Outcoming
            try
            {

                objSqlHelper.OpenConnection();
                List<File> fileList = objSqlHelper.GetFilesList();
                double totalRecord = fileList.Count();
                int counter = 1;

                foreach (var Fileitem in fileList)
                {

                    double progressStatus = (counter / totalRecord) * 100;
                    (sender as BackgroundWorker).ReportProgress((int)progressStatus);

                    //  my code here

                    counter++;
                }

            }
            catch (Exception ex)
            {
                isCompletedSuccessfully = false;
                MessageBox.Show(ex.Message, "Error");

            }
            finally
            {
                if (isCompletedSuccessfully == true)
                {
                    MessageBox.Show("Completed Successfully!", "Information");
                }
                else if (isCompletedSuccessfully == false)
                {
                    // MessageBox.Show("Completed Unsuccessfully!", "Information");
                }

            }
            #endregion



}

 private void Button_Click(object sender, RoutedEventArgs e)
    {
        BackgroundWorker worker = new BackgroundWorker();
        worker.WorkerReportsProgress = true;
        worker.DoWork += worker_DoWork;
        worker.ProgressChanged += worker_ProgressChanged;
        worker.RunWorkerAsync();
      //  worker.RunWorkerAsync();

    }

报告进度时调用的函数

    void  worker_ProgressChanged(object sender, ProgressChangedEventArgs e)
    {

        try
        {
            pbStatus.Value = e.ProgressPercentage; 

        } 
        catch( Exception exp )
        {
            throw exp;
        }    
    }

Answer 1

我猜你需要在将ProgressPercentage值分配给ProgressBar控件后立即引入一些东西，类似于 Application.DoEvents（）在WinForms中所做的事情。在WPF中，您可以通过Dispatcher实现相同的目标。看看它是如何工作的，用这个来理解和实现解决方案可能需要时间。请参阅MSDN中的此代码示例 -

[SecurityPermissionAttribute(SecurityAction.Demand, Flags = SecurityPermissionFlag.UnmanagedCode)]
public void DoEvents()
{
    DispatcherFrame frame = new DispatcherFrame();
    Dispatcher.CurrentDispatcher.BeginInvoke(DispatcherPriority.Background,
        new DispatcherOperationCallback(ExitFrame), frame);
    Dispatcher.PushFrame(frame);
}

public object ExitFrame(object f)
{
    ((DispatcherFrame)f).Continue = false;

    return null;
}

但是，如果你只是想继续前进，你仍然可以在这里使用 Application.DoEvents（），但只能在导入 System.Windows.Forms.dll 之后在你的WPF项目中（这是一种丑陋的解决方案）。

BackgroundWorker.ReportProgress（）不更新属性

1 个答案: