异常 System.Reflection.TargetInvocationException - 后台工作器

Question

我正在尝试用背景工作者（bgFileOpener）将由 openFileDialog 打开的文件读入到一个 richTextBox （称为 websiteInput_rtxt）中。

   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());
    }

当表单关闭时，如果bgWorker仍在运行，则会抛出异常，似乎没有被捕获。请问有什么遗漏或可能导致异常的原因吗？

异常消息称为“System.Reflection.TargetInvocationException”，内部异常显示与RichTextBox有关。

- user2695458

---

精确的内部异常是什么？websiteInput_rtxt.AppendText(e.UserState.ToString()); 是否在工作线程上运行？ - Arian Motamedi

Answer 1

关闭表单并不会立即停止后台工作器，这意味着在表单关闭后仍然可以触发ProgressChanged事件。

您可以通过以下方式解决此问题:

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());
}

- Reed Copsey