Question

我已经浏览过网络，无法看到其他人遇到此问题。我使用的是使用DownloadFileAsync的Web客户端，当调用事件处理程序（DownloadProgressChanged）时，由于某种原因，TotalBytesToReceive（来自DownloadProgressChangedArgs）等于-1，从而阻止我使用进度条。我正在检测＆lt; 0，如果是这样的话，现在只需要猜100meg，就可以了解它。

然而，BytesRecieved正在工作，文件实际上正在下载，并且AsynCompletedEventHadnler似乎被调用，因此它知道它已完成（因此必须以某种方式知道TotalBytesToReceive？）。我使用具有凭据和代理凭据的WebClient从通过内部网络的密码保护外部站点下载（因此需要两者） - 不确定这是否会产生任何影响。

我以前使用WebClient.DownloadData获取字节数据并将其单独保存并将其放入后台工作程序中，并且工作正常（如果速度很慢）但我无法以这种方式显示进度。此外，DownloadFileAsync似乎为我做了所有这些，因此节省了大量代码。

    private void DLFile_AsyncWithStatus(string DLlocation, string un, string pw, string destLoc)
    {
        WebClient wc = new WebClient();
        wc.Credentials = new NetworkCredential(un, pw); // website login
        wc.Proxy.Credentials = new NetworkCredential(ProxyUsername, ProxyPassword, ProxyDomain); //proxy login

        Uri uri = new Uri(DLlocation);

        // Specify that the DownloadFileCallback method gets called when the download completes.
        wc.DownloadFileCompleted += new AsyncCompletedEventHandler(DLFile_AsynWithStatus_Completed);
        // Specify a progress notification handler.
        wc.DownloadProgressChanged += new DownloadProgressChangedEventHandler(DownloadProgressCallback);
        try
        {
            wc.DownloadFileAsync(uri, destLoc);

        }
        catch (WebException e)
        {
            MessageBox.Show(e.Message);
        }

    }
    private void DownloadProgressCallback(object sender, DownloadProgressChangedEventArgs e)
    {

        double bytesIn = double.Parse(e.BytesReceived.ToString());
        double totalBytes = double.Parse(e.TotalBytesToReceive.ToString());
        if (totalBytes < 0) { 
            totalBytes = 100.0 * 1000000.0; //guess 100 meg since it is not detecting total bytes
        } 
        double percentage = bytesIn / totalBytes * 100;


        lblTmpStatus.Text = "Downloaded " + e.BytesReceived + " of " + e.TotalBytesToReceive;

        progressBar1.Value = int.Parse(Math.Truncate(percentage).ToString());
    }
    void DLFile_AsynWithStatus_Completed(object sender, AsyncCompletedEventArgs e)
    {
        if (e.Error != null)
        {
            Msg(e.Error.Message);
        }
        else
        {
            progressBar1.Value = 100;//temp.. finish it off incase was less than 100 meg.
        }
    }

c＃WebClient DownloadProgresschanged TotalBytesToReceive = -1

0 个答案: