C# Base64解码 二进制输出

 /// <summary>
        /// base64 解码Excel下载
        /// </summary>
        /// <param name="excelContent"></param>
        /// <param name="strFileName"></param>
        public void BidExcelDown(string excelContent, string strFileName) {

            Response.Clear(); //清空无关信息
            Response.Buffer= true; //完成整个响应后再发送
            Response.Charset = "GB2312";//设置输出流的字符集-中文
            Response.ContentEncoding = System.Text.Encoding.GetEncoding("UTF-8");//设置输出流的字符集
            Response.AppendHeader("Content-Disposition", "attachment;filename=" + HttpUtility.UrlEncode(strFileName + ".xls", System.Text.Encoding.UTF8));//追加头信息
            Response.ContentType = "application/octet-stream";//输出流的Excel类型
            byte[] outputb = Convert.FromBase64String(excelContent); //解码
           //如果编码是字符串就无需这样解码了
           //二进制的所以输出的时候一定要记得带上下面这句
            Response.BinaryWrite(outputb);//输出二进制的流
            Response.End();//输出停止
        }