異常System.Reflection.TargetInvocationException - Backgroundworker

Question

我正在嘗試使用backgroundworker（bgFileOpener）將openFileDialog打開的文件讀入richTextBox（稱為websiteInput_rtxt）。

   private void bgFileOpener_DoWork(object sender, DoWorkEventArgs e)
    {
        try
        {
            foreach (var file in openFileDialog1.FileNames)
            {
                using (StreamReader sreader = new StreamReader(file))
                {

                    // while the stream reader didn't reach the end of the file - read the next line and report it
                    while (!sreader.EndOfStream)
                    {
                        if (bgFileOpener.CancellationPending)
                        {
                            e.Cancel = true;
                            return;
                        }

                        bgFileOpener.ReportProgress(0, sreader.ReadLine() + "\n");
                        Thread.Sleep(15);
                    }
                }
            }
        }
        catch (Exception) { }

    }

    private void bgFileOpener_ProgressChanged(object sender, ProgressChangedEventArgs e)
    {
            websiteInput_rtxt.AppendText(e.UserState.ToString());
    }

當表格在bgWorker仍在運行時關閉時，會拋出一個似乎沒有被捕獲的異常 ，有人可以告訴我缺少什么或可能導致異常的原因嗎？

異常消息稱為“System.Reflection.TargetInvocationException”，而innerException則表示有關RichTextBox的內容。

Answer 1

關閉表單不會立即停止后台工作程序，這意味着您的ProgressChanged事件仍然可以在窗體關閉后在表單上引發。

你可以解決這個問題：

private void bgFileOpener_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
    if (this.IsDisposed) // Don't do this if we've been closed already
    {
        // Kill the bg work:
        bgFileOpener.CancelAsync();
    }
    else
        websiteInput_rtxt.AppendText(e.UserState.ToString());
}