asp.net里，各种下载方式汇总

        /// <summary>
        /// 下载文件 TransmitFile
        /// </summary>
        /// <param name="filePath"></param>
        public static void DownloadFile(string filePath)
        {
            string filename = HttpContext.Current.Server.MapPath(filePath);
            var response = HttpContext.Current.Response;
            response.ContentType = "application/x-zip-compressed";
            response.AddHeader("Content-Disposition", "attachment;filename=" + Path.GetFileName(filename) );
            response.TransmitFile(filename); 
        }

        /// <summary>
        /// 下载大文件
        /// </summary>
        /// <param name="filePath"></param>
        public static void DownloadBigFile(string filePath)
        {
            filePath =  HttpContext.Current.Server.MapPath(filePath);//路径
            string fileName = Path.GetFileName(filePath);//客户端保存的文件名
            var response = HttpContext.Current.Response;
            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)
                {
                    //读取的大小 Response.OutputStream.Write(buffer, 0, lengthRead);
                    int lengthRead = iStream.Read(buffer, 0, Convert.ToInt32(ChunkSize));
                    response.Flush();
                    dataLengthToRead = dataLengthToRead - lengthRead;
                }

                response.Close();
            }
        }

        /// <summary>
        /// 流方式下载
        /// </summary>
        /// <param name="filePath"></param>
        public static void DownloadFileStream(string filePath)
        {
            filePath = HttpContext.Current.Server.MapPath(filePath);//路径
            string fileName = Path.GetFileName(filePath);//客户端保存的文件名
            var response = HttpContext.Current.Response;
            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();
        }

        /// <summary>
        /// 将文本作为某文件下载
        /// </summary>
        /// <param name="text"></param>
        /// <param name="fileName"></param>
        public static void DownloadText(string text , string fileName)
        {
            byte[] bytes = Encoding.Default.GetBytes(text);
            var response = HttpContext.Current.Response;
            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();
        }