需要指导如何使功能异步/非阻塞

Question

假设我有一个HttpHelper类，它有一个GetResponseStream()，它通过events StatusChanged & ProgressChanged上传显示进度的请求数据。

public MemoryStream GetResponseStream() {
    ...
    Status = Statuses.Uploading; // this doesn't raise StatusChanged
    // write to request stream
    ... // as I write to stream, ProgressChanged doesn't get raised too
    Status = Statuses.Downloading; // this too
    // write to response stream
    ... // same here
    Status = Statuses.Idle; // this runs ok. Event triggered, UI updated
}

代码@pastebin。GetRequestStream()在76线。类本身工作正常，除非使用类需要像下面这样调用它

HttpHelper helper = new HttpHelper("http://localhost/uploadTest.php");
helper.AddFileHeader("test.txt", "test.txt", "text/plain", File.ReadAllBytes("./test.txt"));
helper.StatusChanged += (s, evt) =>
{
    _dispatcher.Invoke(new Action(() => txtStatus.Text = helper.Status.ToString()));

    if (helper.Status == HttpHelper.Statuses.Idle || helper.Status == HttpHelper.Statuses.Error)
        _dispatcher.Invoke(new Action(() => progBar.IsIndeterminate = false));

    if (helper.Status == HttpHelper.Statuses.Error)
        _dispatcher.Invoke(new Action(() => txtStatus.Text = helper.Error.Message));
};
helper.ProgressChanged += (s, evt) =>
{
    if (helper.Progress.HasValue)
        _dispatcher.Invoke(new Action(() => progBar.Value = (double)helper.Progress));
    else
        _dispatcher.Invoke(new Action(() => progBar.IsIndeterminate = true));
};
Task.Factory.StartNew(() => helper.GetResponseString());

如果我打电话给全班

helper.GetResponseString();

这样，类本身就能工作，但事件似乎不会被引发。我认为这与UI线程被阻塞有关。如何对类进行重新编码，使使用类更容易/更干净，而不需要使用所有的_dispatcher & Task。

另外，我想确切地知道导致事件/UI不更新的原因。即使代码是同步的，它也不能运行属性更改/事件，毕竟是在读/写之后吗？

Answer 1

您应该考虑使用BackgroundWorker，而不是自己手工制作。使用ReportProgress将处理状态传递给UI线程。