关于数据筛选后Excel导出下载

        public void Down(StudentI i, int Status = 0)
        {
            List<string> ls = new List<string>();
            List<SqlParameter> lp = new List<SqlParameter>();

            if (i.RecommName != null)
            {
                ls.Add("Recomm=@Recomm");
                lp.Add(new SqlParameter("@Recomm", i.Recomm));
            }
            if (i.DateTime != 0)
            {
                ls.Add("DateTime=@DateTime");
                lp.Add(new SqlParameter("@DateTime", i.DateTime));
            }

            ///取值范围
            DownBLL.DownStudenI(ls, lp.ToArray(), "学员管理");
        }

        public static void DownStudenI(List<string> name, SqlParameter[] parameter, string Title)
        {
            string sql = "select * from StudentI where ";
            foreach (var i in name)
                sql += i + " and ";
            sql += " 0=0";

            DataTable dt = sd.Search(sql, parameter);
            ExcelHelper.CreateExcelToDown(dt, Title);
        }

        /// <summary>
        /// 表转化成excel并且下载
        /// </summary>
        /// <param name="dt">表</param>
        /// <param name="title">文件名</param>
        public static void CreateExcelToDown(DataTable dt, string title)
        {
            using (Workbook book = new HSSFWorkbook())
            {
                Sheet sheet = book.CreateSheet("sheet1");

                Row headerrow = sheet.CreateRow(0);
                CellStyle style = book.CreateCellStyle();
                style.Alignment = HorizontalAlignment.CENTER;
                //1.转化表头
                for (int i = 0; i < dt.Columns.Count; i++)
                {
                    Cell cell = headerrow.CreateCell(i);
                    cell.CellStyle = style;
                    cell.SetCellValue(dt.Columns[i].ColumnName);
                }
                //2.填写数据
                int RowLen = dt.Rows.Count;
                int ColLen = dt.Columns.Count;
                for (int i = 0; i < RowLen; i++)
                {
                    DataRow dr = dt.Rows[i];
                    Row r = sheet.CreateRow((i+1));
                    for (int j = 0; j < ColLen; j++)
                    {
                        r.CreateCell(j).SetCellValue(dr[j].ToString());
                    }
                }
                //3.下载
                using (MemoryStream ms = new MemoryStream())
                {
                    book.Write(ms);
                    HttpContext.Current.Response.AddHeader("Content-Disposition", string.Format("attachment; filename={0}.xls", HttpUtility.UrlEncode(title + "_" + DateTime.Now.ToString("yyyy-MM-dd"), System.Text.Encoding.UTF8)));
                    HttpContext.Current.Response.BinaryWrite(ms.ToArray());
                    HttpContext.Current.Response.End();
                }
            }
        }