使用WebClient在WPF应用程序中下载文件

Question

I'm making a WPF application. I'm using WebClient to download files. I have a list of the name of the files that should be downloaded from a current path. I use an foreach to iterate through each name and then download each file sequency. The name of the file i get from a torrent file which i decode.

public class DownloadGameFile
{
    private DownloadTorrentFile DLTorrent;

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

    private string savePath = @"C:\Program Files (x86)\program\Client\package\downloads\";

    public DownloadGameFile()
    {
        DLTorrent = new DownloadTorrentFile();
        fileInfo = new DirectoryInfo(savePath);
    }
    public bool StartDownload(int torrentId)
    {
        try
        {
            DLTorrent.DecodeTorrent(torrentId);


            //File info from a Directory
            FileInfo[] files = fileInfo.GetFiles();

            foreach (FileInfo i in files)
            {
                Console.WriteLine("Files exit ");
                if (DLTorrent.GameInfomation[i.Name] != i.Length)
                {
                    i.Delete();
                }
                else
                {
                    Console.WriteLine("add files ");
                    ExistFile.Add(i.Name);
                }
            }
            //Make a list which file not downloaded yet
            var res = DLTorrent.GameInfomation.Keys.Except(ExistFile);

            foreach (var x in res)
            {
                Console.WriteLine(x);
            }

            foreach (var x in res)
            {
                DownloadProtocol("http://cdn.path.com/rental/" + torrentId + "/" + x, savePath + x);
            }

            return true;

        }
        catch
        {
            return false;
        }
    }

    public void DownloadProtocol(string address, string location)
    {
        WebClient client = new WebClient();
        Uri Uri = new Uri(address);

        client.DownloadFileCompleted += new AsyncCompletedEventHandler(Completed);

        client.DownloadProgressChanged += new DownloadProgressChangedEventHandler(DownloadProgress);
        client.DownloadFileAsync(Uri, location);


    }


    private void DownloadProgress(object sender, DownloadProgressChangedEventArgs e)
    {
        // Displays the operation identifier, and the transfer progress.
        Console.WriteLine("{0}    downloaded {1} of {2} bytes. {3} % complete...",
            (string)e.UserState,
            e.BytesReceived,
            e.TotalBytesToReceive,
            e.ProgressPercentage);
    }

    private void Completed(object sender, AsyncCompletedEventArgs e)
    {
        if (e.Cancelled == true)
        {
            Console.WriteLine("Download has been canceled.");
        }
        else
        {

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

This code work fine in an Console app with a current thread blocker. But when I use the same code in an WPF app It doesn't. I'm using a button to execute the StartDownload() function, but when I do that it start downloading all the files at the same time. Example the first file get 3% done and then it switch to another file and so on. I really don't know why this isn't working.

Answer 1

Have you considered not using .DownloadFileAsync? You can try .DownloadFile and start DownloadProtocol() with a single background thread. Although I think you'll have to rethink your DownloadProgress output.

I do something very similar within a winform.