oa_mvc_easyui——分页(4)

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Data;
using System.Data.SqlClient;
using Itcast.CMS.Model;

namespace Itcast.CMS.DAL
{
    public class NewListInfoDal
    {

        /// <summary>
        /// 用于分页，根据start,end 取出数据
        /// </summary>
        /// <param name="start"></param>
        /// <param name="end"></param>
        /// <returns></returns>
        public List<T_News> GetPageEntityList(int start,int end)
        {
            string sql = " select * from (select row_number() over(order by id) as num, * from T_News) as t where t.num>=@start and t.num<=@end ";
            SqlParameter[] pars ={
                                      new SqlParameter("@start",SqlDbType.Int),
                                      new SqlParameter("@end",SqlDbType.Int)
                                  };
            pars[0].Value = start;
            pars[1].Value = end;

            DataTable dt = DAL.SqlHelper.SelectSqlReturnDataTable(sql, CommandType.Text, pars);

            List<T_News> newlist_list = null;
            if(dt.Rows.Count>0)
            {
                newlist_list = new List<T_News>();
                //遍历每一行添加到集合中
                T_News newlist =null;
                foreach(DataRow row in dt.Rows)
                {
                    newlist = new T_News();
                    LoadEntity(row, newlist);
                    newlist_list.Add(newlist);
                }
            }
            return newlist_list;
        }

        public void LoadEntity(DataRow row,T_News newlist)
        {
            newlist.Id = Convert.ToInt32(row["id"].ToString());
            newlist.Title = row["Title"] != DBNull.Value ? row["Title"].ToString() : string.Empty;
            newlist.Msg = row["Msg"] != DBNull.Value ? row["Msg"].ToString() : string.Empty;
            newlist.Author = row["Author"] != DBNull.Value ? row["Author"].ToString() : string.Empty;
            newlist.ImagePath = row["ImagePath"] != DBNull.Value ? row["ImagePath"].ToString() : string.Empty;
            newlist.SubDateTime = Convert.ToDateTime(row["SubDateTime"].ToString());
        }

        /// <summary>
        /// 获取T_News表中，总的条数
        /// </summary>
        /// <returns></returns>
        public int GetRecordCount()
        {
            string sql = " select count(*) from  T_News ";
            object ob = DAL.SqlHelper.selectSqlReturnObject(sql, CommandType.Text);
            ob = ob != DBNull.Value ? ob : string.Empty;
            return Convert.ToInt32(ob.ToString());
        }

    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Itcast.CMS.Model;
using Itcast.CMS.DAL;

namespace Itcast.CMS.BLL
{
    public class NewListInfoService
    {

        DAL.NewListInfoDal NewListInfo = new DAL.NewListInfoDal();

        /// <summary>
        /// 返回每页的数据
        /// </summary>
        /// <param name="PageIndex">当前页</param>
        /// <param name="PageSize">每页的条数</param>
        /// <returns></returns>
        public List<T_News> GetPageEntityList(int PageIndex,int PageSize)
        {
            //公式计算每页的第一条，最好一条
            int start = (PageIndex - 1) * PageSize + 1;
            int end = PageIndex * PageSize;
            return NewListInfo.GetPageEntityList(start, end);
        }

        /// <summary>
        /// 获取总的页数
        /// </summary>
        /// <returns></returns>
        public int GetPageCount(int PageSize)
        {
            int recordCount = NewListInfo.GetRecordCount();
            int PageCount = Convert.ToInt32(Math.Ceiling((double)recordCount / PageSize));
            return PageCount;
        }
            
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Itcast.CMS.Common
{
    public class PageBar
    {
        public static string GetPageBar(int pageIndex,int pageCount)
        {
            if (pageCount == 1)
            {
                return string.Empty;
            }
            int start = pageIndex - 5;
            start = start < 1 ? 1 : start;
            int end = start + 9;
            if (end > pageCount)
            {
                end = pageCount;
                start = end - 9 > 0 ? end - 9 : 1;
            }
            StringBuilder sb = new StringBuilder();
            if (pageIndex > 1)
            {
                sb.Append(string.Format("<a href=‘?PageIndex={0}‘>上一页</a>", pageIndex - 1));
            }
            for (int i = start; i <= end; i++)
            {
                if (i == pageIndex)
                {
                    sb.Append(i);
                }
                else
                {
                    sb.Append(string.Format("<a href=‘?PageIndex={0}‘>{0}</a>", i));
                }
            }
            if (pageIndex < pageCount)
            {
                sb.Append(string.Format("<a href=‘?PageIndex={0}‘>下一页</a>", pageIndex + 1));
            }
            return sb.ToString();
        }
    }
}