从服务器下载文件的方法

public static void DownloadFile(string physicalFilePath){    FileStream stream=null;    stream = new FileStream(physicalFilePath, FileMode.Open, FileAccess.Read, FileShare.Read);       int bufSize = (int)stream.Length;    byte[] buf = new byte[bufSize];    int bytesRead = stream.Read(buf, 0, bufSize);    HttpContext.Current.Response.ContentType = "application/octet-stream";    HttpContext.Current.Response.AppendHeader("Content-Disposition","attachment;filename="+System.IO.Path.GetFileName(physicalFilePath));    HttpContext.Current.Response.OutputStream.Write(buf, 0, bytesRead);    HttpContext.Current.Response.End();}