同时调用多个 DownloadFileAsync 阻塞 UI 个线程

Question

我正在制作一个 WPF 应用程序，我在其中使用 WebClient 从网络服务器下载文件。我的代码现在一次下载一个文件并等待该文件完成，然后再开始下一个文件，依此类推。我有几个存储文件名称的列表 - 就像一个文件夹。当我单击第一个按钮时，下载开始依次下载第一个文件夹中的文件，但是当第一次下载正在进行时，我想通过单击第二个按钮从第二个文件夹开始下载，我的应用程序冻结了。我希望我的应用程序同时运行多个 DownloadFileAsync。我试图为每次下载启动一个新线程，但这似乎也不起作用。

public partial class MainWindow : Window
{
    public MainWindow()
    {
        InitializeComponent();

    }

    private void StartButton_Click(object sender, RoutedEventArgs e)
    {


        DownloadGameFile dlg = new DownloadGameFile();
        dlg.StartDownload(11825);

    }

    private void button1_Click(object sender, RoutedEventArgs e)
    {
        DownloadGameFile dlg = new DownloadGameFile();
        dlg.StartDownload(11198);
    }
}

class DownloadGameFile
{
    private DownloadTorrentFile DLTorrent;

    //List of file that already exist
    private List<string> ExistFile = new List<string>();
    DirectoryInfo fileInfo;

    private string savePath = @"C:somewhere";
    public string path { get; set; }

    private bool isDelete = false;
    public DownloadGameFile()
    {
        DLTorrent = new DownloadTorrentFile();

    }
    public async void StartDownload(int torrentId)
    {
        try
        {
            DLTorrent.DecodeTorrent(torrentId);

            //Creates a folder to the game
            var newdic = Directory.CreateDirectory(savePath + torrentId);

            fileInfo = new DirectoryInfo(savePath + torrentId);
            //File info from a Directory
            FileInfo[] files = fileInfo.GetFiles();

            foreach (FileInfo i in files)
            {
                Console.WriteLine("Files exit " + i);
                if (DLTorrent.GameInfomation[i.Name] != i.Length)
                {
                    i.Delete();
                    isDelete = true;
                }
                else
                {
                    Console.WriteLine("add files ");
                    ExistFile.Add(i.Name);
                }

            }
            //Make a list which file not downloaded yet
            var res = DLTorrent.GameInfomation.Keys.Except(ExistFile);

            var nFiles = files.Length;
            if(nFiles == 0 || !isDelete)
            {
                nFiles++;
                foreach (var x in res)
                {
                    ((MainWindow)System.Windows.Application.Current.MainWindow).label1.Content = nFiles + " out of " + DLTorrent.GameInfomation.Keys.Count();
                    await DownloadProtocol("http://cdn.somewhere/rental/" + torrentId + "/" + x, savePath + torrentId + "/" + x);
                    nFiles++;
                }
            }
            else
            {
                foreach (var x in res)
                {

                    ((MainWindow)System.Windows.Application.Current.MainWindow).label1.Content = nFiles + " out of " + DLTorrent.GameInfomation.Keys.Count();
                    await DownloadProtocol("http://cdn.somewhere/rental/" + torrentId + "/" + x, savePath + torrentId + "/" + x);
                    nFiles++;
                }
            }
        }
        catch
        {

        }

    }


    public async Task DownloadProtocol(string address, string location)
    {

        Uri Uri = new Uri(address);
        using (WebClient client = new WebClient())
        {
            client.DownloadProgressChanged += (o, e) =>
            {
                Console.WriteLine(e.BytesReceived + " " + e.ProgressPercentage);
                ((MainWindow)System.Windows.Application.Current.MainWindow).DownloadBar.Value = e.ProgressPercentage;
            };

            client.DownloadFileCompleted += (o, e) =>
            {
                if (e.Cancelled == true)
                {
                    Console.WriteLine("Download has been canceled.");
                }
                else
                {

                    Console.WriteLine("Download completed!");
                }

            };

            await client.DownloadFileTaskAsync(Uri, location);
        }

    }


}

Answer 1

你试过这个吗：

private async void StartButton_Click(object sender, RoutedEventArgs e)
{
    DownloadGameFile dlg = new DownloadGameFile();
    await dlg.StartDownload(11825);
}

dlg.StartDownload 必须 return 一个任务。

同时调用多个 DownloadFileAsync 阻塞 UI 个线程

Calling multiple DownloadFileAsync at the same time block UI thread

c#

wpf

multithreading

webclient

task