Question

对不起，如果之前已经回答过这个问题，但没有一个答案对我有帮助。我的WebView有一个事件：

private async void MainWebView_UnviewableContentIdentified(WebView sender, WebViewUnviewableContentIdentifiedEventArgs args)
{
    await downloadFromUri(args.Uri).ConfigureAwait(false);
}

我的downloadFromUri方法将尝试下载文件并将其存储在downloads文件夹中，最后它将打开文件：

    static async Task downloadFromUri(Uri uri)
    {
        var url = uri;

        HttpClient client = new HttpClient();

        client.DefaultRequestHeaders.TryAppendWithoutValidation(
          "Authorization Bearer",
              " MYTOKEN"
              );

        Debug.WriteLine("Attempting GET request");

        var response = await client.GetAsync(url);

        Debug.WriteLine("Got response.. checking " + response.StatusCode);


        if (response.IsSuccessStatusCode)
        {
            Debug.WriteLine("Okay, we've got a response");
            var responseFileName = response.Content.Headers.ContentDisposition.FileName;

            Debug.WriteLine("Filename: " + responseFileName);

            var ManualFile = await DownloadsFolder.CreateFileAsync(responseFileName, CreationCollisionOption.GenerateUniqueName);

            Debug.WriteLine("Creating buffer: ");
            var buffer = await client.GetBufferAsync(url);

            Debug.WriteLine("Writing buffer.");
            await Windows.Storage.FileIO.WriteBufferAsync(ManualFile, buffer);

            Debug.WriteLine("Done, opening");

            var openOptions = new Windows.System.LauncherOptions();
            openOptions.DisplayApplicationPicker = true;

            var openFile = await Windows.System.Launcher.LaunchFileAsync(ManualFile, openOptions);
        }
        else
        {
            Debug.WriteLine(response.StatusCode.ToString());
        }     
    }

问题是，这个代码似乎可以在小PDF或zip文件上正常工作。但是当涉及到＆gt;的PDF文件时10mb，应用程序挂起在以下行：

var response = await client.GetAsync（url）;

我可以做些什么来完成这项工作？非常感谢提前！

注意：我使用的是Windows.Web.Http.HttpClient，而不是System.Net.Http.HttpClient。

修改：我已尝试跳过client.GetAsync(url)并直接运行var buffer = await client.GetBufferAsync(url);。这也会挂起。

Answer 1

对于较大的文件，最好使用

Windows.Networking.BackgroundTransfer

命名空间，如BackgroundDownloader？

Answer 2

请将您的代码更改为 -

var response = await client.GetAsync(url, HttpCompletionOption.ResponseHeadersRead).ConfigureAwait(false));

另请参阅此 - HttpClient.GetAsync(...) never returns when using await/async

或者，您也可以使用TPL在任务中执行长时间运行的功能，该任务将管理OS线程池。

var result = Task.Run(() => downloadFromUri(uri)).Result;

HttpClient getAsync挂在较大的文件上

2 个答案: