Question

protected void downloadFunction(string filename)
{
    string filepath = @"D:\XtraFiles\" + filename;
    string contentType = "application/x-newton-compatible-pkg";

    Stream iStream = null;
    // Buffer to read 1024K bytes in chunk
    byte[] buffer = new Byte[1048576];

    // Length of the file:
    int length;
    // Total bytes to read:
    long dataToRead;

    try
    {
        // Open the file.
        iStream = new FileStream(filepath, FileMode.Open, FileAccess.Read, FileShare.Read);

        // Total bytes to read:
        dataToRead = iStream.Length;
        HttpContext.Current.Response.ContentType = contentType;
        HttpContext.Current.Response.AddHeader("Content-Disposition", "attachment; filename=" + HttpUtility.UrlEncode(filename, System.Text.Encoding.UTF8));

        // Read the bytes.
        while (dataToRead > 0)
        {
            // Verify that the client is connected.
            if (HttpContext.Current.Response.IsClientConnected)
            {
                // Read the data in buffer.
                length = iStream.Read(buffer, 0, 10000);

                // Write the data to the current output stream.
                HttpContext.Current.Response.OutputStream.Write(buffer, 0, length);

                // Flush the data to the HTML output.
                HttpContext.Current.Response.Flush();

                buffer = new Byte[10000];
                dataToRead = dataToRead - length;
            }
            else
            {
                //prevent infinite loop if user disconnects
                dataToRead = -1;
            }
        }
    }
    catch (Exception ex)
    {
        // Trap the error, if any.
        HttpContext.Current.Response.Write("Error : " + ex.Message + "<br />");
        HttpContext.Current.Response.ContentType = "text/html";
        HttpContext.Current.Response.Write("Error : file not found");
    }
    finally
    {
        if (iStream != null)
        {
            //Close the file.
            iStream.Close();
        }
        HttpContext.Current.Response.End();
        HttpContext.Current.Response.Close();
    }
}

My donwload function is working perfect, but when users are downloading the browser cant see the total file size of the download.

So now the browser says eq. Downloading 8mb of ?, insted of Downloading 8mb of 142mb.

What have i missed?

Answer 1

The Content-Length header seems to be what you are missing.

If you set this the browser will then know how much to expect. Otherwise it will just keep going til you stop sending data and it won’t know how long it is until the end.

Response.AddHeader("Content-Length", iStream.Length);

You may also be interested in Response.WriteFile whcih can provide an easier way to send a file to a client without having to worry about streams yourself.