#region 下载文件处理-downfiledeal
        /// <summary>
        /// 下载文件处理
        /// </summary>
        /// <param name="ResourceID">资源id</param>
        /// <param name="UserID">用户id</param>
        /// <param name="downtype">下载类型：1-购买，2-今日免费，3-订阅用户</param>
        /// <param name="webtitle">提示页面titie</param>
        /// <param name="ResourceType">资源类型（暂时不考虑）</param>
        /// <returns></returns>
        private string downfiledeal(string ResourceID, string UserID, string downtype, string webtitle, string ResourceType = "")
        {
            TopicInformationBLL bll_tf = new TopicInformationBLL();
            TopicInformation tf = bll_tf.GetById(ResourceID);
            bll_tf.Dispose();
            string FilePath = "";
            FilePath = tf.TopicSourceFile.ToLower();
            if (FilePath.StartsWith("http://www.***.com"))//不是外网文件夹服务器路径
            {
                FilePath = FilePath.Replace("http://www.***.com", "");
            }
            if (!FilePath.StartsWith("/")) FilePath = "/" + FilePath;
            FilePath = Server.MapPath(FilePath);
            FileInfo DownloadFile = new FileInfo(FilePath);
            System.IO.Stream iStream = null;
            int downsize = 1024;//读取web.config中的配置
            try { downsize = Convert.ToInt32(System.Configuration.ConfigurationManager.AppSettings["downsize"]); }
            catch { downsize = 1024; }
            int buffersize = 1024 * downsize;//默认每次发送1K;
            byte[] buffer = new Byte[buffersize];// Buffer to read 10K bytes in chunk:
            int currentlength;// Length of each read to buffer:
            long dataToRead;// Total bytes to read:
            long dataSended;//已发送的字节
            long datalength;//文件字节总长度
            string filename = System.IO.Path.GetFileName(FilePath); // Identify the file name.
            try
            {
                System.Collections.Specialized.NameValueCollection hds = Request.Headers;
                long startBytes = 0;
                Response.Clear();
                Response.ClearHeaders();
                if (Request.Headers["Range"] != null)
                {//------如果是续传请求，则获取续传的起始位置，即已经下载到客户端的字节数------  
                    Response.StatusCode = 206;//重要：续传必须，表示局部范围响应。初始下载时默认为200  
                    string[] range = Request.Headers["Range"].Split(new char[] { '=', '-' });//"bytes=1474560-"  
                    startBytes = Convert.ToInt64(range[1]);//已经下载的字节数，即本次下载的开始位置    
                    if (startBytes < 0 || startBytes >= DownloadFile.Length)
                    {//无效的起始位置  
                        startBytes = 0;
                    }
                }
                iStream = new System.IO.FileStream(FilePath, System.IO.FileMode.Open, System.IO.FileAccess.Read, System.IO.FileShare.Read);// Open the file.
                dataSended = 0;
                datalength =
                dataToRead = iStream.Length - startBytes;// Total bytes to read:
                Response.Buffer = true;
                string lastUpdateTiemStr = System.IO.File.GetLastWriteTimeUtc(FilePath).ToString("r");
                string eTag = HttpUtility.UrlEncode(filename, Encoding.UTF8) + lastUpdateTiemStr;
                Response.AppendHeader("ETag", "\"" + eTag + "\"");//重要：续传必须 
                if (startBytes > 0)
                {
                    if (Request.Headers["If-Range"] != null)//（IE,360）对应响应头ETag：文件名+文件最后修改时间  
                    {
                        //----------上次被请求的日期之后被修改过-------------- 
                        string If_Range = Request.Headers["If-Range"].Replace("\&quo