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所以这是我第一次尝试使用委托、事件、Backgroundworkers、WPF……几乎所有东西都是新的。我有一个运行长时间运行的方法的外部类，我想报告进度：

public class ShortFileCreator
{
    public void CreateShortUrlFile(string outputfilepath)
    {         
        foreach(string line in lines)
        {
                //work work work processing file
                if (ReportProgress != null)
                {
                //report progress that a file has been processed
                    ReportProgress(this, new ProgressArgs {TotalProcessed = numberofurlsprocessed
                                                         , TotalRecords = _bitlyFile.NumberOfRecords});
                }
        }
    }

    public delegate void ReportProgressEventHandler (object sender, ProgressArgs args);

    public event ReportProgressEventHandler ReportProgress;

    public class ProgressArgs : EventArgs
    {
        public int TotalProcessed { get; set; }
        public int TotalRecords { get; set; }
    }
}

在我的 WPF 表单中，我想启动 CreateShortUrlFile 方法并更新表单的进度条。

private void btnRun_Click(object sender, RoutedEventArgs e)
    {
       var shortFileCreator = new ShortFileCreator();           

        _worker = new BackgroundWorker
        {
            WorkerReportsProgress = true,
            WorkerSupportsCancellation = true
        };

        shortFileCreator.ReportProgress += ShortFileCreator_ReportProgress;

        _worker.DoWork += delegate(object s, DoWorkEventArgs args)
        {
            _bitlyFileWorker.CreateShortUrlFile(saveFileDialog.FileName);
        };

        _worker.RunWorkerAsync();
    }

    protected void ShortFileCreator_ReportProgress(object sender, ShortFileCreator.ProgressArgs e)
    {
        //update progress bar label
        txtProgress.Content = String.Format("{0} of {1} Records Processed", e.TotalProcessed, e.TotalRecords);
        //update progress bar value
        progress.Value = (double) e.TotalProcessed/e.TotalRecords;
    }

但是，当我运行它时，它会处理一行，然后出现异常：调用线程无法访问此对象，因为另一个线程拥有它。什么其他线程拥有这个？ReportProgress 事件不应该将 ProgressArgs 返回给任何订阅者吗？

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1 回答 1

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ProgressBar这是因为像和之类的 UI 控件TextBox不能被另一个线程触及，在这种情况下，您正试图从BackgroundWorker线程中更新它们。

解决此问题的一种方法是Invoke回调 UI 线程，您可以使用Dispatcher

protected void ShortFileCreator_ReportProgress(object sender, ShortFileCreator.ProgressArgs e)
{
    Dispatcher.Invoke((Action)delegate
    {
       //update progress bar label
       txtProgress.Content = String.Format("{0} of {1} Records Processed", e.TotalProcessed, e.TotalRecords);
       //update progress bar value
       progress.Value = (double) e.TotalProcessed/e.TotalRecords;
    });
}
于 2013-10-17T03:12:12.920 回答