public static void CreateExcel(DataSet ds)
        {
            string filename = DateTime.Now.ToString("yyyyMMddHHmmssff") + ".xls";
            HttpContext.Current.Response.ContentEncoding = System.Text.Encoding.GetEncoding("GB2312");
            HttpContext.Current.Response.AppendHeader("Content-Disposition", "attachment;filename=" + filename);
            string colHeaders = "", ls_item = "";

            //定义表对象与行对象，同时用DataSet对其值进行初始化
            DataTable dt = ds.Tables[0];
            DataRow[] myRow = dt.Select();//可以类似dt.Select("id>10")之形式达到数据筛选目的
            int i = 0;
            int cl = dt.Columns.Count;

            //取得数据表各列标题，各标题之间以\t分割，最后一个列标题后加回车符
            for (i = 0; i < cl; i++)
            {
                if (i == (cl - 1))//最后一列，加\n
                {
                    colHeaders += dt.Columns[i].Caption.ToString() + "\n";
                }
                else
                {
                    colHeaders += dt.Columns[i].Caption.ToString() + "\t";
                }

            }
            HttpContext.Current.Response.Write(colHeaders);
            //向HTTP输出流中写入取得的数据信息

            //逐行处理数据 
            foreach (DataRow row in myRow)
            {
                //当前行数据写入HTTP输出流，并且置空ls_item以便下行数据   
                for (i = 0; i < cl; i++)
                {
                    if (i == (cl - 1))//最后一列，加\n
                    {
                        ls_item += row[i].ToString() + "\n";
                    }
                    else
                    {
                        ls_item += row[i].ToString() + "\t";
                    }

                }
                HttpContext.Current.Response.Write(ls_item);
                ls_item = "";

            }
            HttpContext.Current.Response.End();
        }