/// <summary>
    /// 把DataTable内容导出excel并返回客户端 
    /// </summary>
    /// <param name="header">标题行</param>
    /// <param name="fileName">文件名称</param>
    public void DataTable2Excel(TableCell[] header, string fileName)
    {
       // IO用于导出并返回excel文件 
       var strWriter = new StringWriter();
       var htmlWriter = new HtmlTextWriter(strWriter);
       // 设置编码和附件格式 
       Response.ContentType = "application/ms-excel";
       Response.ContentEncoding = Encoding.GetEncoding("gb2312");
       Response.Charset = "gb2312";
       if (!string.IsNullOrEmpty(fileName))
       {
           fileName = HttpUtility.UrlEncode(fileName, Encoding.UTF8);//处理中文名乱码问题
           Response.AppendHeader("Content-Disposition", ("attachment;filename=" + (fileName.ToLower().EndsWith(".xls") ? fileName : fileName + ".xls")));
       }
       Response.Flush();
       var gvExport = new GridView();// 重新定义一个无分页的GridView var dt = new DataTable();//这里是要导出的数据
       gvExport.DataSource = dt.DefaultView;
       gvExport.AllowPaging = false;
       gvExport.RowDataBound += dgExport_RowDataBound; //优化导出数据显示，如身份证、12-1等显示异常问题
       gvExport.DataBind();
       if (header != null && header.Length > 0)//处理表头
       {
            gvExport.HeaderRow.Cells.Clear();
            gvExport.HeaderRow.Cells.AddRange(header);
       }
       gvExport.RenderControl(htmlWriter);// 返回客户端 
       Response.Write(strWriter);
       Response.End();
    }

    /// <summary>
    /// 用来优化导出数据显示
    /// </summary>
    /// <param name="sender"></param>
    /// <param name="e"></param>
    protected void dgExport_RowDataBound(object sender, GridViewRowEventArgs e)
    {
        if (e.Row.RowType != DataControlRowType.DataRow) return;
        foreach (var cell in e.Row.Cells.Cast<TableCell>().Where(cell => Regex.IsMatch(cell.Text.Trim(), @"^\d{12,}$") || Regex.IsMatch(cell.Text.Trim(), @"^\d+[-]\d+$")))
        {
            cell.Attributes.Add("style", "vnd.ms-excel.numberformat:@");
        }
    }