asp.net分页方法

        /// </summary>
        /// <param name="ds">DataSet实例</param>
        /// <param name="datalistname">DataList名称</param>
        /// <param name="pagesize">分页大小</param>
        public static string GetPageNum(DataSet ds, DataList datalistname, int pagesize, int page)
        {
            // string sql0 = "SELECT TOP 10 * FROM Blobs WHERE id NOT IN(SELECT TOP (10*(2-1)) id FROM Blobs ORDER BY id) ORDER BY id select count(*) from Blobs";//两种分页sql
           // string sql = "SELECT TOP 5 * FROM (SELECT ROW_NUMBER() OVER (ORDER BY id) AS RowNumber,* FROM Blobs) A WHERE RowNumber > 5*(" + page + "-1);select count(*) from Blobs";
            int total = (int)ds.Tables[1].Rows[0][0];//总页数
            datalistname.DataSource = ds.Tables[0];
            datalistname.DataBind();
            int allpage = 0;
            int next = 0;
            int pre = 0;
            int startcount = 0;
            int endcount = 0;
            string pagestr = "";
            if (page < 1) { page = 1; }
            //计算总页数
            if (pagesize != 0)
            {
                allpage = (total / pagesize);
                allpage = ((total % pagesize) != 0 ? allpage + 1 : allpage);
                allpage = (allpage == 0 ? 1 : allpage);
            }
            next = page + 1;
            pre = page - 1;
            startcount = (page + 5) > allpage ? allpage - 9 : page - 4;//中间页起始序号
            //中间页终止序号
            endcount = page < 5 ? 10 : page + 5;
            if (startcount < 1) { startcount = 1; } //为了避免输出的时候产生负数，设置如果小于1就从序号1开始
            if (allpage < endcount) { endcount = allpage; } //页码+5的可能性就会产生最终输出序号大于总页码，那么就要将其控制在页码数之内
            pagestr = "<a >" + "共" + allpage + "页</a>&nbsp;&nbsp;&nbsp;&nbsp;";
            pagestr += page > 1 ? "<a href=\"" + HttpContext.Current.Request.CurrentExecutionFilePath + "?page=1\">首页</a>&nbsp;&nbsp;<a href=\"" + HttpContext.Current.Request.CurrentExecutionFilePath + "?page=" + pre + "\">上一页</a>" : "<a>首页</a>" + "&nbsp;&nbsp;" + "<a>上一页</a>";
            //中间页处理，这个增加时间复杂度，减小空间复杂度
            for (int i = startcount; i <= endcount; i++)
            {
                pagestr += page == i ? "&nbsp;&nbsp;" + "<strong><a class=\"cpb\">" + i + "</a></strong>" : "&nbsp;&nbsp;<a href=\"" + HttpContext.Current.Request.CurrentExecutionFilePath + "?page=" + i + "\">" + i + "</a>";
            }
            pagestr += page != allpage ? "&nbsp;&nbsp;<a href=\"" + HttpContext.Current.Request.CurrentExecutionFilePath + "?page=" + next + "\">下一页</a>&nbsp;&nbsp;<a href=\"" + HttpContext.Current.Request.CurrentExecutionFilePath + "?page=" + allpage + "\">末页</a>" : "&nbsp;&nbsp;" + "<a >下一页</a>" + "&nbsp;&nbsp;" + "<a >末页</a>";
            return pagestr;
        }