导出规则的EXCEL文件并下载,该如何解决

//// <summary>        /// 导出 Excel 文件        /// </summary>        /// <param name="ds">要导出的DataSet</param>        /// <param name="strExcelFileName">要导出的文件名</param>        public static void ExportExcel(DataSet ds, string strExcelFileName)        {            object objOpt = Missing.Value;            Application excel = new Application();            excel.Visible = true;            _Workbook wkb = excel.Workbooks.Add(objOpt);            _Worksheet wks = (_Worksheet)wkb.ActiveSheet;            wks.Visible = XlSheetVisibility.xlSheetVisible;            int rowIndex = 1;            int colIndex = 0;            System.Data.DataTable table = ds.Tables[0];            foreach (DataColumn col in table.Columns)            {                colIndex++;                excel.Cells[1, colIndex] = col.ColumnName;            }            foreach (DataRow row in table.Rows)            {                rowIndex++;                colIndex = 0;                foreach (DataColumn col in table.Columns)                {                    colIndex++;                    excel.Cells[rowIndex, colIndex] = row[col.ColumnName].ToString();                }            }            //excel.Sheets[0] = "sss";            wkb.SaveAs(strExcelFileName, objOpt, null, null, false, false, XlSaveAsAccessMode.xlNoChange, null, null, null, null, null);            wkb.Close(false, objOpt, objOpt);            excel.Quit();        }        #endregion

public void OutPutExcel()        {            //定义文档类型、字符编码             Response.Clear();　　         Response.Buffer= true;　　         Response.Charset="GB2312";            //下面这行很重要， attachment 参数表示作为附件下载，您可以改成 online在线打开　　        //filename=FileFlow.xls 指定输出文件的名称，注意其扩展名和指定文件类型相符，可以为：.doc 　　 .xls 　　 .txt 　　.htm　　         Response.AppendHeader("Content-Disposition","attachment;filename=FileFlow.xls");　　         Response.ContentEncoding=System.Text.Encoding.GetEncoding("GB2312");　　        //Response.ContentType指定文件类型 可以为application/ms-excel、application/ms-word、application/ms-txt、application/ms-html 或其他浏览器可直接支持文档　　         Response.ContentType = "application/ms-excel";　　        this.EnableViewState = false;            //　定义一个输入流　　         System.IO.StringWriter oStringWriter = new System.IO.StringWriter();　　         System.Web.UI.HtmlTextWriter oHtmlTextWriter = new System.Web.UI.HtmlTextWriter(oStringWriter);            this.RenderControl(oHtmlTextWriter);　　        //this 表示输出本页，你也可以绑定datagrid,或其他支持obj.RenderControl()属性的控件　　         Response.Write(oStringWriter.ToString());　　         Response.End();         }
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C# code
StringBuilder sb = new StringBuilder();        foreach (DataRow dr in ds.Tables[0].Rows)        {            Content = dr["Site"].ToString() + "," + dr["Title"].ToString() + "," + dr["Company"].ToString() + "," + dr["Location"].ToString() + "," + dr["PublishTime"].ToString() + "," + dr["Trade"].ToString();            sb.AppendLine(Content);        }        Response.Clear();        Response.Buffer = false;        Response.ContentEncoding = System.Text.Encoding.GetEncoding("GB2312");        Response.ContentType = "application/octet-stream";        Response.AppendHeader("content-disposition", "attachment;filename=" + FileName);        Response.Write(sb.ToString());        Response.Flush();        Response.End();