Enable Resume and Pause option when downloading file in asp.net

Hi nedash,

I have creted a sample that full-fill your requirement.

Code

protected void Page_Load(object sender, EventArgs e)
{
    string source = @"C:\Users\Public\Videos\Sample Videos\Wildlife.wmv";
    DownloadFileMethod(HttpContext.Current, source, 204800);//204800 is 200kb/s.
}
public static bool DownloadFileMethod(HttpContext httpContext, string filePath, long speed)
{
    var response = httpContext.Response;
    var request = httpContext.Request;
    var method = request.HttpMethod.ToUpper();
    if (method != "GET" && method != "HEAD")
    {
        response.StatusCode = 501;
        return false;
    }
    if (!File.Exists(filePath))
    {
        response.StatusCode = 404;
        response.Write(Path.GetFileName(filePath) + " does not exist.");
        return false;
    }
    using (var myFile = new FileStream(filePath, FileMode.Open, FileAccess.Read, FileShare.ReadWrite))
    {
        var fileLength = myFile.Length;
        if (fileLength > Int32.MaxValue)
        {
            response.StatusCode = 413;
            return false;
        }
        var lastUpdateTiemStr = File.GetLastWriteTimeUtc(filePath).ToString("r");
        var fileName = Path.GetFileName(filePath);
        var fileNameUrlEncoded = HttpUtility.UrlEncode(fileName, Encoding.UTF8);
        var eTag = fileNameUrlEncoded + lastUpdateTiemStr;
        var ifRange = request.Headers["If-Range"];
        if (ifRange != null && ifRange.Replace("\"", "") != eTag)
        {
            response.StatusCode = 412;
            return false;
        }
        long startBytes = 0;
        var rangeHeader = request.Headers["Range"];
        if (rangeHeader != null)
        {
            response.StatusCode = 206;
            var range = rangeHeader.Split(new[] { '=', '-' });
            startBytes = Convert.ToInt64(range[1]);
            if (startBytes < 0 || startBytes >= fileLength)
            {
                response.StatusCode = (int)HttpStatusCode.BadRequest;
                response.StatusDescription =
                    string.Format("Invalid start of range: {0}", startBytes);
                return false;
            }
        }
        response.Clear();
        response.Buffer = false;
        var fileInfo = new FileInfo(filePath);
        response.AddHeader("Content-MD5", GetMD5Hash(fileInfo));
        response.AddHeader("Accept-Ranges", "bytes");
        response.AppendHeader("ETag", string.Format("\"{0}\"", eTag));
        response.AppendHeader("Last-Modified", lastUpdateTiemStr);
        response.ContentType = "application/octet-stream";
        response.AddHeader("Content-Disposition", "attachment;filename=" + fileNameUrlEncoded.Replace("+", "%20"));
        var remaining = fileLength - startBytes;
        response.AddHeader("Content-Length", remaining.ToString());
        response.AddHeader("Connection", "Keep-Alive");
        response.ContentEncoding = Encoding.UTF8;
        if (startBytes > 0)
        {
            response.AddHeader("Content-Range", string.Format(" bytes {0}-{1}/{2}", startBytes, fileLength - 1, fileLength));
        }
        using (var br = new BinaryReader(myFile))
        {
            br.BaseStream.Seek(startBytes, SeekOrigin.Begin);
            const int packSize = 1024 * 10;
            var maxCount = (int)Math.Ceiling((remaining + 0.0) / packSize);
            for (var i = 0; i < maxCount && response.IsClientConnected; i++)
            {
                response.BinaryWrite(br.ReadBytes(packSize));
                response.Flush();
                var sleep = (int)Math.Ceiling(1000.0 * packSize / speed);
                if (sleep > 1)
                {
                    Thread.Sleep(sleep);
                }
            }
        }
    }
    return true;
}
private static string GetMD5Hash(FileInfo file)
{
    var stream = file.OpenRead();
    MD5 md5 = new MD5CryptoServiceProvider();
    byte[] retVal = md5.ComputeHash(stream);
    stream.Close();
    var sb = new StringBuilder();
    for (int i = 0; i < retVal.Length; i++)
    {
        sb.Append(retVal[i].ToString("x2"));
    }
    return sb.ToString();
}

Screenshot