错误导出griddata到MS excel从Asp.net webform应用程序

Question

我使用了Asp.net webform c＃。使用时将网格数据导出到excel，我收到以下错误消息 “文件格式和传输模式的扩展名.xls不匹配。文件可能已损坏或不安全。除非您信任其来源，否则不要打开它。无论如何都要打开它”

点击“是”后数据显示正常。

代码：

    Response.ClearContent();
    Response.Buffer = true;
    Response.AddHeader("content-disposition", string.Format("attachment; filename={0}", "Customers.xls"));
    Response.ContentType = "application/ms-excel";
    System.IO.StringWriter sw = new System.IO.StringWriter();
    HtmlTextWriter htw = new HtmlTextWriter(sw);
    gvmodeoftransport.AllowPaging = false;

    for (int i = 0; i < gvmodeoftransport.HeaderRow.Cells.Count; i++)
    {
        gvmodeoftransport.HeaderRow.Cells[i].Style.Add("background-color", "#df5015");
    }
    gvmodeoftransport.RenderControl(htw);
    Response.Write(sw.ToString());
    Response.End();