/// </summary>

     /// <param name="total">总记录数</param>

     /// <param name="per">每页记录数</param>

     /// <param name="page">当前页数</param>

     /// <param name="query_string">Url参数</param>

     private string pagination(int total, int per, int page, string query_string)

     {

         int allpage = ;

         int next = ;

         int pre = ;

         int startcount = ;

         int endcount = ;

         string pagestr = "";

         if (page < ) { page = ; }

         //计算总页数

         if (per != )

         {

             allpage = (total / per);

             allpage = ((total % per) !=  ? allpage +  : allpage);

             allpage = (allpage ==  ?  : allpage);

         }

         next = page + ;

         pre = page - ;

         startcount = (page + ) > allpage ? allpage -  : page - ;//中间页起始序号

         //中间页终止序号

         endcount = page <  ?  : page + ;

         if (startcount < ) { startcount = ; } //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 = "共" + allpage + "页&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;";

         pagestr += page >  ? "<a href=\"" + query_string + "?page=1\">首页</a>&nbsp;&nbsp;<a href=\"" + query_string + "?page=" + pre + "\">上一页</a>" : "首页 上一页";

         //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;<font color=\"#ff0000\">" + i + "</font>" : "&nbsp;&nbsp;<a href=\"" + query_string + "?page=" + i + "\">" + i + "</a>";

         }

         pagestr += page != allpage ? "&nbsp;&nbsp;<a href=\"" + query_string + "?page=" + next + "\">下一页</a>&nbsp;&nbsp;<a href=\"" + query_string + "?page=" + allpage + "\">末页</a>" : " 下一页 末页";

         return pagestr;

     }