如何在c＃

Question

我是编程的初学者，我想知道在UWP中下载文件的正确方法我现在使用它，但它只能在50％的时间内起作用：

public async Task StartDownload()
{
    try
    {
        StorageFile sf = await DownloadsFolder.CreateFileAsync(title.Text, CreationCollisionOption.GenerateUniqueName);
        downloadFolder = (await sf.GetParentAsync()).ToString();
        HttpClient client = new HttpClient();
        byte[] buffer = await client.GetByteArrayAsync(inputURL);
        using (Stream stream = await sf.OpenStreamForWriteAsync())
        {
            stream.Write(buffer, 0, buffer.Length);
        }
        path = sf.Path;
    }
    catch (Exception e)
    {
        MessageDialog dialog = new MessageDialog("Sorry, something went wrong...", "An error...");
        await dialog.ShowAsync();
    }
}

例外是： ＆＃34; 0x750F6D7E处的未处理异常（program.exe 0xC000027B中的combase.dll; 发生了应用程序内部异常（参数：0x16E73128,0x00000001）。＆＃34;

提前致谢

Answer 1

有两种方法可以做到这一点 第一个是像你一样使用HttpClient（这适用于小文件）

第二个是使用BackgroundDownloader Class。这是推荐的方式

 private async void StartDownload_Click(object sender, RoutedEventArgs e)
    {
        try
        {
            Uri source = new Uri(inputURL);

            StorageFile destinationFile = await KnownFolders.PicturesLibrary.CreateFileAsync(
                title.Text, CreationCollisionOption.GenerateUniqueName);

            BackgroundDownloader downloader = new BackgroundDownloader();
            DownloadOperation download = downloader.CreateDownload(source, destinationFile);

            // Attach progress and completion handlers.
            HandleDownloadAsync(download, true);
        }
        catch (Exception ex)
        {
            LogException("Download Error", ex);
        }
    }