web开发下的各种下载方法

利用TransmitFile方法，解决Response.BinaryWrite下载超过400mb的文件时导致Aspnet_wp.exe进程回收而无法成功下载的问题。 代码如下：

 Response.ContentType = "application/x-zip-compressed";  Response.AddHeader("Content-Disposition", "attachment;filename=z.zip");  string filename = Server.MapPath("DownLoad/aaa.zip");  Response.TransmitFile(filename);

IO的WriteFile实现下载

 string fileName ="aaa.zip";//客户端保存的文件名  string filePath=Server.MapPath("DownLoad/aaa.zip");//路径  FileInfo fileInfo = new FileInfo(filePath);  Response.Clear();  Response.ClearContent();  Response.ClearHeaders();  Response.AddHeader("Content-Disposition", "attachment;filename=" + fileName);  Response.AddHeader("Content-Length", fileInfo.Length.ToString());  Response.AddHeader("Content-Transfer-Encoding", "binary");  Response.ContentType = "application/octet-stream";  Response.ContentEncoding = System.Text.Encoding.GetEncoding("gb2312");  Response.WriteFile(fileInfo.FullName);  Response.Flush();  Response.End();

WriteFile分块下载

string fileName = "aaa.zip";//客户端保存的文件名  string filePath = Server.MapPath("DownLoad/aaa.zip");//路径  System.IO.FileInfo fileInfo = new System.IO.FileInfo(filePath);  if (fileInfo.Exists == true)  {  const long ChunkSize = 102400;//100K 每次读取文件，只读取100Ｋ，这样可以缓解服务器的压力  byte[] buffer = new byte[ChunkSize];  Response.Clear();  System.IO.FileStream iStream = System.IO.File.OpenRead(filePath);  long dataLengthToRead = iStream.Length;//获取下载的文件总大小  Response.ContentType = "application/octet-stream";  Response.AddHeader("Content-Disposition", "attachment; filename=" + HttpUtility.UrlEncode(fileName));  while (dataLengthToRead > 0 && Response.IsClientConnected)   {  int lengthRead = iStream.Read(buffer, 0, Convert.ToInt32(ChunkSize));//读取的大小  Response.OutputStream.Write(buffer, 0, lengthRead);  Response.Flush();  dataLengthToRead = dataLengthToRead - lengthRead;  }  Response.Close();  }

  //流方式下载

 string fileName = "aaa.zip";//客户端保存的文件名  string filePath = Server.MapPath("DownLoad/aaa.zip");//路径  //以字符流的形式下载文件  FileStream fs = new FileStream(filePath, FileMode.Open);  byte[] bytes = new byte[(int)fs.Length];  fs.Read(bytes, 0, bytes.Length);  fs.Close();  Response.ContentType = "application/octet-stream";  //通知浏览器下载文件而不是打开  Response.AddHeader("Content-Disposition", "attachment; filename=" + HttpUtility.UrlEncode(fileName, System.Text.Encoding.UTF8));  Response.BinaryWrite(bytes);  Response.Flush();  Response.End();

最后一种支持断点下载

/// <summary>        /// 支持断点续传的下载大文件的函数        /// </summary>        /// <param name="downloadFilePath">被下载文件的路径，相对和绝对都可以</param>        /// <param name="showFileName">显示给用户的文件名，可以为空</param>        /// <param name="fileType">要下载的文件类型，如果不确定，请留空</param>        /// <remarks>用于大文件的下载</remarks>        public static void BigFileDownload(string downloadFilePath, string showFileName, string fileType)        {            downloadFilePath = downloadFilePath.Trim();            if(string.Empty == downloadFilePath)                ShowErrorMessage("没有指定要下载的文件路径！");                        if(downloadFilePath.IndexOf(":") < 0)                downloadFilePath = System.Web.HttpContext.Current.Server.MapPath(downloadFilePath);            showFileName = showFileName.Trim();            if(string.Empty == showFileName)                showFileName = Path.GetFileName(downloadFilePath);            showFileName = System.Web.HttpUtility.UrlEncode(System.Web.HttpContext.Current.Request.ContentEncoding.GetBytes(showFileName));                        fileType = fileType.Trim();            if(string.Empty == fileType)                fileType = "application/octet-stream";            System.Web.HttpContext.Current.Response.Clear();            Stream objStream = null;            byte[] btBuffer = new byte[8192];  // 1024*8 = 8Kb            int intLength = 0;            long lngData2Read = 0;            try            {                using(objStream = new FileStream(downloadFilePath, FileMode.Open, FileAccess.Read, FileShare.Read))                {                    lngData2Read = objStream.Length;                                        输出HTTP头信息                                        while(lngData2Read > 0)                    {                        if(HttpContext.Current.Response.IsClientConnected)                        {                            intLength = objStream.Read(btBuffer, 0, 8192);                            HttpContext.Current.Response.OutputStream.Write(btBuffer, 0, intLength);                            HttpContext.Current.Response.Flush();                            lngData2Read -= intLength;                            btBuffer = new byte[8192];                        }                        else                        {                            lngData2Read = -1;                        }                    }                }            }            catch(Exception ex)            {                ShowErrorMessage(ex.Message);            }            // 结束文件下载，此句不可缺少，否则会把本页的HTML代码一起下载文件里            HttpContext.Current.Response.End();        }        /// <summary>        /// 输出错误信息给用户，采用客户端弹出框的方式        /// </summary>        /// <param name="errorMessage">错误信息的内容</param>        internal static void ShowErrorMessage(string errorMessage)        {            errorMessage = errorMessage.Replace("'", "\"");            System.Web.HttpContext.Current.Response.Write("<script language='javascript'>");            System.Web.HttpContext.Current.Response.Write("alert('");            System.Web.HttpContext.Current.Response.Write(errorMessage);            System.Web.HttpContext.Current.Response.Write("');</script>");            System.Web.HttpContext.Current.Response.End();        }