'How do I Async download multiple files using webclient, but one at a time?

It has been surprisingly hard to find a code example of downloading multiple files using the webclient class asynchronous method, but downloading one at a time.

How can I initiate a async download, but wait until the first is finished until the second, etc. Basically a que.

(note I do not want to use the sync method, because of the increased functionality of the async method.)

The below code starts all my downloads at once. (the progress bar is all over the place)

private void downloadFile(string url)
        {
            WebClient client = new WebClient();

            client.DownloadProgressChanged += new DownloadProgressChangedEventHandler(client_DownloadProgressChanged);
            client.DownloadFileCompleted += new AsyncCompletedEventHandler(client_DownloadFileCompleted);

            // Starts the download
            btnGetDownload.Text = "Downloading...";
            btnGetDownload.Enabled = false;
            progressBar1.Visible = true;
            lblFileName.Text = url;
            lblFileName.Visible = true;
            string FileName = url.Substring(url.LastIndexOf("/") + 1,
                            (url.Length - url.LastIndexOf("/") - 1));
             client.DownloadFileAsync(new Uri(url), "C:\\Test4\\" + FileName);

        }

        void client_DownloadFileCompleted(object sender, AsyncCompletedEventArgs e)
        {

        }

        void client_DownloadProgressChanged(object sender, DownloadProgressChangedEventArgs e)
        {
            double bytesIn = double.Parse(e.BytesReceived.ToString());
            double totalBytes = double.Parse(e.TotalBytesToReceive.ToString());
            double percentage = bytesIn / totalBytes * 100;
            progressBar1.Value = int.Parse(Math.Truncate(percentage).ToString());
        }
c++sharpasynchronouswebclient


Solution 1:[1]

I am struggling to understand where the issue is. If you only call the async method for the first file, won't it only download that file? Why not use the client_downlaodFileCompleted event to initiate the next file download based on some value passed by AsyncCompletedEvents, or maintain a list of downloaded files as a static variable and have client_DownloadFileCompleted iterate tht list to find the next file to download.

Hope that helps but please post more information if I have miunderstood your question.

Solution 2:[2]

I would make a new method, for example named getUrlFromQueue which returns me a new url from the queue (collection or array) and deletes it.. then it calls downloadFile(url) - and in client_DownloadFileCompleted I call getUrlFromQueue again.

Sources

This article follows the attribution requirements of Stack Overflow and is licensed under CC BY-SA 3.0.

Source: Stack Overflow

Solution Source
Solution 1 Jason James
Solution 2 MilMike

Related Questions