Windows Runtime provides the HttpClient class along with async APIs. For example, you can send a GET request through the GetAsync(Uri) method.
GetAsync() method is an awaitable API so that it returns IAsyncOperationWithProgress<HttpResponseMessage, HttpProgress>^. You will get the HttpResponseMessage by specifying the IAsyncOperationWithProgress to Concurrency::create_task(). However, how can I get the progress?
There’s no direct answer from MSDN but gives a hint here:
You just supply the delegate for the object’s Progress property
Here’s the snippet:
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| void WebCrawlerSample::MainPage::button_Click(Platform::Object^ sender, Windows::UI::Xaml::RoutedEventArgs^ e) | |
| { | |
| HttpClient^ client = ref new HttpClient(); | |
| Uri^ addr = ref new Uri("https://heejune.me"); | |
| auto asyncOp = client->GetAsync(addr); | |
| // create and set Progress handler | |
| asyncOp->Progress = ref new AsyncOperationProgressHandler<HttpResponseMessage^, HttpProgress>( | |
| [=](IAsyncOperationWithProgress<HttpResponseMessage^, HttpProgress>^ pretask, HttpProgress progressInfo) { | |
| // access ui element | |
| Windows::ApplicationModel::Core::CoreApplication::MainView->CoreWindow->Dispatcher->RunAsync( | |
| CoreDispatcherPriority::Normal, | |
| ref new Windows::UI::Core::DispatchedHandler([this, progressInfo]() { | |
| textBlock->Text += progressInfo.BytesReceived.ToString() + "\n"; | |
| })); | |
| }); | |
| auto task = create_task(asyncOp); | |
| // get result | |
| task.then([=](HttpResponseMessage ^ msg) { | |
| // access ui element | |
| Windows::ApplicationModel::Core::CoreApplication::MainView->CoreWindow->Dispatcher->RunAsync( | |
| CoreDispatcherPriority::Normal, | |
| ref new Windows::UI::Core::DispatchedHandler([this, msg]() { | |
| textBlock->Text += msg->StatusCode.ToString(); | |
| })); | |
| }); | |
| } |
it's compiling 