asp.net c# 斷點續傳 下載 Accept-Ranges

標籤：

轉自：http://www.cnblogs.com/90nice/p/3489287.html

1.因為要下載大檔案 需要斷點續傳，使用多線程 分段下載 效率比較高，節省資源。

發點牢騷：下載可以用多線程，如果是上傳 我覺得沒必要了。如果是普通使用者(adsl) 上傳速度只有50KB/s  據我所知100MB光纖 家庭使用者下載理論值能達到12.5MB/S 但是上傳目前卻只有 256kb/s   這點速度夠幹啥的。希望以後 上傳下載速度能一致。

下面是一個簡單的例子：

服務端：

如果是分段下載 在http Header 標頭檔裡 要有Range ，下面會有 用戶端的例子。

var range = Request.Headers["Range"]; if (null == range) { //正常情況 200 Response.StatusCode = 200; Response.ContentType = "application/x-zip-compressed"; Response.AddHeader("Content-Disposition", "attachment;filename=" + fName); FileStream fs = new FileStream(fUrl, FileMode.Open); long len = fs.Length; fs.Close(); fs.Dispose(); Response.AddHeader("Accept-Ranges", len.ToString()); Response.TransmitFile(fUrl); } else { //Accept - Range 情況string[] re = range.Split(‘=‘); string[] r = re[1].Split(‘-‘); long start = 0; long alength = 0; long fslength = 0; // 如果開始為空白 從0開始取if (string.IsNullOrEmpty(r[0])) start = 0; else start = Convert.ToInt64(r[0]); //取檔案總長度FileStream fs = new FileStream(fUrl, FileMode.Open); fslength = fs.Length; fs.Close(); fs.Dispose(); // 位元組長度 if (string.IsNullOrEmpty(r[1])) alength = fslength - start; else alength = Convert.ToInt64(r[1]) - start; Response.StatusCode = 206;  //分段下載狀態Response.ContentType = "application/x-zip-compressed"; Response.AddHeader("Content-Disposition", "attachment;filename=" + fName); Response.AddHeader("Accept-Ranges", (alength - start).ToString()); Response.AddHeader("Content-Range", "bytes " + start + "-" + (start + alength) + "/" + fslength.ToString()); //Content-Range： bytes 100-200/1024 告訴用戶端 本次請求的檔案位置和總檔案大小// 檔案路徑 開始位置 取多少位元組Response.TransmitFile(fUrl, start, alength);

用戶端 例子：

建立一個 http請求 並 寫入請求的檔案段

var request = (HttpWebRequest)WebRequest.Create("http://localhost:40337/PublicPage/ZrqPublicImg.zip"); request.AddRange(0, 500); try { //擷取HTTP回應，注意HttpWebResponse繼承自IDisposable using (var response = (HttpWebResponse)request.GetResponse()) { if (response.StatusCode == HttpStatusCode.OK) throw new Exception("檔案不支援Range部分下載"); //設定接收資訊的緩衝器var bytes = new byte[5000]; //擷取回應的Stream（位元組流）using (var stream = response.GetResponseStream()) {//FileMode.Append 我這裡是從檔案末尾處寫入        如果是多線程 就要根據具體的請求的位置 寫入檔案using (var outStream = new FileStream(@"D:\222.jpg", FileMode.Append, FileAccess.Write, FileShare.None)) { const int bufferLen = 4096; byte[] buffer = new byte[bufferLen]; int count = 0;while ((count = stream.Read(buffer, 0, bufferLen)) > 0) { outStream.Write(buffer, 0, count); } outStream.Close(); stream.Close(); } } } } catch (Exception ex) { Console.WriteLine("錯誤資訊：{0}", ex.Message); }

 

 以下摘自：http://www.sufeinet.com/forum.php?mod=viewthread&tid=2258&extra=page%3D1%26filter%3Dtypeid%26typeid%3D284%26typeid%3D284

另附支援限速下載的方法（伺服器代碼）：

/// <summary>        ///  輸出硬碟檔案，提供下載 支援大檔案、續傳、速度限制、資源佔用小        /// </summary>        /// <param name="_Request">;Page.Request對象</param>        /// <param name="_Response">;Page.Response對象</param>        /// <param name="_fileName">下載檔案名稱</param>        /// <param name="_fullPath">帶檔案名稱下載路徑</param>        /// <param name="_speed">每秒允許下載的位元組數</param>        /// <returns>返回是否成功</returns>        //---------------------------------------------------------------------        //調用：        // string FullPath=Server.MapPath("count.txt");        // ResponseFile(this.Request,this.Response,"count.txt",FullPath,100);        //---------------------------------------------------------------------        public static bool ResponseFile(HttpRequest _Request, HttpResponse _Response, string _fileName, string _fullPath, long _speed)        {            try            {                FileStream myFile = new FileStream(_fullPath, FileMode.Open, FileAccess.Read, FileShare.ReadWrite);                BinaryReader br = new BinaryReader(myFile);                try                {                    _Response.AddHeader("Accept-Ranges", "bytes");                    _Response.Buffer = false;                     long fileLength = myFile.Length;                    long startBytes = 0;                    int pack = 10240;  //10K bytes                    int sleep = (int)Math.Floor((double)(1000 * pack / _speed)) + 1;                     if (_Request.Headers["Range"] != null)                    {                        _Response.StatusCode = 206;                        string[] range = _Request.Headers["Range"].Split(new char[] { ‘=‘, ‘-‘ });                        startBytes = Convert.ToInt64(range[1]);                    }                    _Response.AddHeader("Content-Length", (fileLength - startBytes).ToString());                    if (startBytes != 0)                    {                        _Response.AddHeader("Content-Range", string.Format(" bytes {0}-{1}/{2}", startBytes, fileLength - 1, fileLength));                    }                     _Response.AddHeader("Connection", "Keep-Alive");                    _Response.ContentType = "application/octet-stream";                    _Response.AddHeader("Content-Disposition", "attachment;filename=" + HttpUtility.UrlEncode(_fileName, System.Text.Encoding.UTF8));                     br.BaseStream.Seek(startBytes, SeekOrigin.Begin);                    int maxCount = (int)Math.Floor((double)((fileLength - startBytes) / pack)) + 1;                     for (int i = 0; i < maxCount; i++)                    {                        if (_Response.IsClientConnected)                        {                            _Response.BinaryWrite(br.ReadBytes(pack));                            Thread.Sleep(sleep);                        }                        else                        {                            i = maxCount;                        }                    }                }                catch                {                    return false;                }                finally                {                    br.Close();                    myFile.Close();                }            }            catch            {                return false;            }            return true;        }    }

 

asp.net c# 斷點續傳 下載 Accept-Ranges