/// <summary>
        /// 导出合并的gridview
        /// </summary>
        /// <param name="dataSource">数据源</param>
        /// <param name="startColoum">要合并起始列，初始值：0</param>
        /// <param name="endColoum">要合并的结束列序号</param>
        /// <param name="filename">导出的文件名</param>
        /// <returns></returns>
        public virtual ActionResult ExportMergedGridViewToExcel(object dataSource, int startColoum, int endColoum, string filename = "excel")
        {
            GridView gv = new GridView();
            gv.DataSource = dataSource;
            gv.DataBind();
            MergeGridViewCell.MergeRow(gv, startColoum, endColoum);
            Response.ClearContent();
            Response.Clear();
            Response.Charset = "UTF8";
            Response.ContentEncoding = Encoding.UTF8;
          
            if (Request.Browser.Browser.ToLower() != "firefox")
            {
                filename = HttpUtility.UrlEncode(Encoding.UTF8.GetBytes(filename));
            }
            Response.AddHeader("content-disposition", "attachment; filename=" + filename + ".xls"); Response.ContentType = "application/ms-excel";
            StringWriter sw = new StringWriter();
            #region 解决数据第一个字符0导出被过滤掉的问题
         
            string strStyle = "<style>td{mso-number-format:\"\\@\";}</style>";
            sw.WriteLine(strStyle);
            #endregion
            HtmlTextWriter htw = new HtmlTextWriter(sw);
            //gv.RenderControl(htw);
            //Response.Output.Write("<meta http-equiv=\"content-type\" content=\"application/vnd.ms-excel; charset=utf-8\"/>" + sw.ToString());
            if (gv.Rows.Count > 0)
            {
                gv.RenderControl(htw);
                Response.Output.Write("<meta http-equiv=\"content-type\" content=\"application/vnd.ms-excel; charset=utf-8\"/>" + sw.ToString());
            }
            Response.Flush();
            Response.End();

            return Content("");
        }