UI阻止了HttpWebRequest回调

Question

EDITED: On Windows Phone I am calling HttpWebRequest.BeginGetResponse on a separate thread that I started. Then I call MessageBox.Show(). The problem is that the callback is not called until I dismiss the MessageBox.

void GetResponseCallback(IAsyncResult asynchronousResult) {
    //Not getting called until I dismiss MessageBox
}

void getWeb() {
    Thread.Sleep(1000);
    HttpWebRequest request = (HttpWebRequest)WebRequest.Create(new Uri(url));
    request.Method = "GET";
    request.BeginGetResponse(new AsyncCallback(GetResponseCallback), request);
}

new Thread(getWeb).Start(); //Start a new thread
MessageBox.Show();

Should the MessageBox be blocking the callback on the background thread?

Answer 1

Need to add a reference to Microsoft.Phone.Reactive

Try this:

private void PushMe_Click(object sender, RoutedEventArgs e)
        {
            var scheduler = Scheduler.NewThread;
            scheduler.Schedule(action => GetWeb());         
            MessageBox.Show("This is a test.", "Test caption.", MessageBoxButton.OK);
        }

        private void GetWeb()
        {
            Thread.Sleep(3000);
            var httpWebRequest = (HttpWebRequest) WebRequest.Create("http://www.stackoverflow.com");
            httpWebRequest.Method = "GET";

            httpWebRequest.BeginGetResponse(BeginGetResponseCallback, httpWebRequest);
        }

        private void BeginGetResponseCallback(IAsyncResult ar)
        {

        }

Answer 2

"MessageBox.Show();" will block your ui thread .

but i don't think it is the reason the GetResponseCallback does not run.

you can test it , comment that code.

Answer 3

if you want to use MessageBox.Show();

then place a this inside dispacher

void GetResponseCallback(IAsyncResult asynchronousResult) 
{
    Dispatcher.BeginInvoke(() =>
    {
        MessageBox.Show("Done");
    });

}

void getWeb() {
    Thread.Sleep(1000);
    HttpWebRequest request = (HttpWebRequest)WebRequest.Create(new Uri(url));
    request.Method = "GET";
    request.BeginGetResponse(new AsyncCallback(GetResponseCallback), request);
}

new Thread(getWeb).Start(); //Start a new thread