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copied!<p>Here is the best approach:</p> <pre><code> public static bool DownloadFile(HttpContext httpContext, string filePath, long speed) { // Many changes: mostly declare variables near use // Extracted duplicate references to HttpContext.Response and .Request // also duplicate reference to .HttpMethod // Removed try/catch blocks which hid any problems 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; return false; } // Stream implements IDisposable so should be in a using block using (var myFile = new FileStream(filePath, FileMode.Open, FileAccess.Read)) { 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; // Just guessing, but I bet you want startBytes calculated before // using to calculate content-length 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) { // TODO: Find correct status code response.StatusCode = (int)HttpStatusCode.BadRequest; response.StatusDescription = string.Format("Invalid start of range: {0}", startBytes); return false; } } response.Clear(); response.Buffer = false; response.AddHeader("Content-MD5", GetMD5Hash(filePath)); 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").Replace(",",";")); 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)); } // BinaryReader implements IDisposable so should be in a using block using (var br = new BinaryReader(myFile)) { br.BaseStream.Seek(startBytes, SeekOrigin.Begin); const int packSize = 1024 * 10; //read in block，every block 10K bytes var maxCount = (int)Math.Ceiling((remaining + 0.0) / packSize); //download in block for (var i = 0; i < maxCount && response.IsClientConnected; i++) { response.BinaryWrite(br.ReadBytes(packSize)); response.Flush(); // HACK: Unexplained sleep var sleep = (int)Math.Ceiling(1000.0 * packSize / speed); //the number of millisecond if (sleep > 1) Thread.Sleep(sleep); } } } return true; } static string GetMD5Hash(string input) { // Create a new instance of the MD5CryptoServiceProvider object. MD5 md5Hasher = MD5.Create(); // Convert the input string to a byte array and compute the hash. byte[] data = md5Hasher.ComputeHash(Encoding.Default.GetBytes(input)); // Create a new Stringbuilder to collect the bytes // and create a string. StringBuilder sBuilder = new StringBuilder(); // Loop through each byte of the hashed data // and format each one as a hexadecimal string. for (int i = 0; i < data.Length; i++) { sBuilder.Append(data[i].ToString("x2")); } // Return the hexadecimal string. return sBuilder.ToString(); } </code></pre>

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