导出excel

   public void CreateExcel(DataSet ds, string FileName)
        {
            StringBuilder builder = new StringBuilder();

            //定义表对象与行对像，同时用DataSet对其值进行初始化
            DataTable tb = ds.Tables[0];
            DataRow[] myRow = tb.Select("");

            builder.Append("<table cellspacing=\"0\" cellpadding=\"5\" rules=\"all\" border=\"1\">");
            //写出列名
            builder.Append("<tr style=\"font-weight: bold; white-space: nowrap;\">");
            foreach (DataColumn column in tb.Columns)
            {
                builder.Append("<td>" + column.ColumnName + "</td>");
            }
            builder.Append("</tr>");

            //写出数据
            foreach (DataRow row in tb.Rows)
            {
                builder.Append("<tr>");
                foreach (DataColumn column in tb.Columns)
                {
                    if (column.ColumnName.Equals("公司订单号") || column.ColumnName.Equals("总订单号"))
                        builder.Append("<td style=\"vnd.ms-excel.numberformat:@\">" + row[column].ToString() + "</td>");
                    else
                        builder.Append("<td>" + row[column].ToString() + "</td>");
                }
                builder.Append("</tr>");
            }
            builder.Append("</table>");

            using (System.IO.StreamWriter sw = new StreamWriter(HttpContext.Current.Server.MapPath("/OrderFile/" + FileName + ".xls"), false, System.Text.Encoding.GetEncoding("GB2312")))
            {
                sw.Write(builder);
                sw.Close();
                sw.Dispose();
            }

            Response.AppendHeader("Content-Disposition", "attachment;filename=/OrderFile/" + FileName + ".xls");
            Response.ContentEncoding = System.Text.Encoding.GetEncoding("GB2312");
            Response.AppendHeader("Content-Type", "application/vnd.ms-excel");
            Response.WriteFile("/OrderFile/" + FileName + ".xls");
            Response.End();

        }