wap页面文件（图片、MP4等）下载

        /// <summary>
        /// 文件下载
        /// </summary>
        /// <param name="filePath">物理路径（推荐使用Server.MapPath）</param>
        /// <param name="isBinaryWrite">是否采用二进制的方式输出（一般为false，对某些特殊的文件如pdf可设置为true）</param>
        public static void OutPutFile(string filePath, bool isBinaryWrite)
        {
            if (string.IsNullOrEmpty(filePath))
                return;
            FileInfo fi = new FileInfo(filePath);
            if (fi.Exists)
            {
                System.IO.Stream iStream = null;
                byte[] buffer = new Byte[10000];
                int length;
                long dataToRead;
                string filename = System.IO.Path.GetFileName(filePath);
                try
                {
                    iStream = new System.IO.FileStream(filePath, System.IO.FileMode.Open, System.IO.FileAccess.Read, System.IO.FileShare.Read);
                    dataToRead = iStream.Length;
                    HttpContext.Current.Response.ContentType = "application/octet-stream";
                    HttpContext.Current.Response.AddHeader("Content-Disposition", "attachment; filename=" + filename);
                    while (dataToRead > 0)
                    {
                        if (HttpContext.Current.Response.IsClientConnected)
                        {
                            length = iStream.Read(buffer, 0, 4096);
                            if (isBinaryWrite == false)
                                HttpContext.Current.Response.OutputStream.Write(buffer, 0, length);
                            else
                                HttpContext.Current.Response.BinaryWrite(buffer);
                            HttpContext.Current.Response.Flush();
                            buffer = new Byte[4096];
                            dataToRead = dataToRead - length;
                        }
                        else
                        {
                            dataToRead = -1;
                        }
                    }
                }
                catch (Exception ex)
                {
                    //
                }
                finally
                {
                    if (iStream != null)
                    {
                        iStream.Close();
                    }
                }
            }
        }