. NET download files from the server

public void Downfile (string guid)        {            var filetransfer = new Filetransfer ();            var directorypath = Path.Combine (Initinfo.config_garbagepath, "FileImport", GUID);            Filetransfer.chunktransfer (System.Web.HttpContext.Current, Getdownfilepath (DirectoryPath));            HttpContext.Response.Flush ();            Delete temporary files            //   utility.deletedirectory (DirectoryPath);        }

 public bool Chunktransfer (HttpContext HttpContext, String filepathname) {bool result = false; if (!                System.IO.File.Exists (Filepathname)) {httpContext.Response.StatusCode = 404;            return false;            } long startpostion = 0;            Long endpostion = 0;            String fileName = Path.getfilename (filepathname);                using (FileStream FileStream = new FileStream (filepathname, FileMode.Open, FileAccess.Read, FileShare.Read)) { using (BinaryReader br = new BinaryReader (FileStream)) {Long filelength                    = Filestream.length; String lastupdatetime = SYSTEM.IO.FILE.GETLASTWRITETIMEUTC (filepathname).                    ToString ("R");                     String eTag = Httputility.urlencode (FileName, Encoding.UTF8) + lastupdatetime;//Retrieve the request header when downloading;         if (httpcontext.request.headers["If-range"]! = null) {               if (httpcontext.request.headers["If-range"]. Replace ("\" "," ")! = ETag) {//file Modified HttpContext.Response.StatusCode =                        412;//preprocessing failed return false;                    }} httpContext.Response.Clear ();                    HttpContext.Response.Buffer = false;                    HttpContext.Response.AddHeader ("accept-ranges", "bytes");                    HttpContext.Response.AppendHeader ("ETag", "\" "+ ETag +" \ "); HttpContext.Response.AppendHeader ("last-modified", lastupdatetime);//write the last modified date to the response HTTP                    Context.Response.ContentType = "Application/octet-stream"; if (HttpContext.Request.UserAgent.IndexOf ("MSIE") >-1 | |                    (HttpContext.Request.UserAgent.IndexOf ("Like Gecko") >-1)) {filename = httputility.urlencode (filename, Encoding.UTF8). Replace ("+ ","%20 "); } if (HttpContext.Request.UserAgent.ToLower (). IndexOf ("Firefox") >-1) {HttpContext.Response.AddHeader ("Content-dispositio                    N "," attachment;filename=\ "" + filename + "\" "); } else {HttpContext.Response.AddHeader ("content-disposition"                    , "attachment;filename=" + filename);                    } httpContext.Response.AddHeader ("Connection", "keep-alive");                    httpContext.Response.ContentEncoding = Encoding.UTF8; if (httpcontext.request.headers["Range"] = null)//CONT. {HttpContext.Response.Sta Tuscode = 206;//continued identity string[] range = httpcontext.request.headers["range"].                        Split (new char[] {' = ', '-'}); Startpostion = long. Parse (range[1]);//The number of bytes already downloaded if (startpostion< 0 | |                        Startpostion >= filelength) {return false; } if (string. IsNullOrEmpty (range[2])//Specify only the request file start {HttpContext.Response.AddHeader ("Co Ntent-range ", String.                            Format ("bytes {0}-{1}/{2}", Startpostion, FileLength-1, filelength)); HttpContext.Response.AddHeader ("Content-length", (filelength-startpostion).                        ToString ()); } else//Specifies the request file range {endpostion = long.                            Parse (range[2]); HttpContext.Response.AddHeader ("Content-range", String.                            Format ("bytes {0}-{1}/{2}", Startpostion, Endpostion-startpostion-1, filelength)); HttpContext.Response.AddHeader ("Content-length", (endpostion-startpostion).                        ToString ());                   }                    } else {//non-continuous HttpContext.Response.AddHeader ("Content-range", String.                        Format ("bytes {0}-{1}/{2}", Startpostion, FileLength-1, filelength)); HttpContext.Response.AddHeader ("Content-length", (filelength-startpostion).                    ToString ()); } br.                    Basestream.seek (Startpostion, Seekorigin.begin);                      Long MaxCount = (long) math.ceiling ((filelength-startpostion + 0.0)/transferbuffer);//block download, the remainder can be divided into the number of blocks                        for (long i = 0; i < maxCount && httpContext.Response.IsClientConnected; i++) { HttpContext.Response.BinaryWrite (Br.                        Readbytes (Transferbuffer));                        HttpContext.Response.Flush ();                        if (Transfersleep > 0) {thread.sleep (transfersleep);        }} result = true;        }} return result; }

. NET download files from the server