简单实用的分页类

一、写一个分页类

using System;
using System.Text;
using System.Diagnostics;

namespace Zhuwenfeng
{
    public class MyPager
    {
        /// <summary>
        /// 总数据条数
        /// </summary>
        public int TotalCount { get; set; }

        /// <summary>
        /// 每页数据条数
        /// </summary>
        public int PageSize { get; set; }

        /// <summary>
        /// 当前页码（从1开始）
        /// </summary>
        public int CurrentPageIndex { get; set; }

        /// <summary>
        /// 显示出来最多的页码数量，因为假设有100页，不可能把100页都显示到界面上
        /// </summary>
        public int MaxPagerCount { get; set; }

        /// <summary>
        /// 页码链接的地址格式，页码用{n}占位。
        /// </summary>
        public string UrlFormat { get; set; }

        public MyPager()
        {
            PageSize = 10;
            MaxPagerCount = 10;
        }

        /// <summary>
        /// 尝试从字符串pn中解析当前页面赋值给CurrentPageIndex
        /// </summary>
        /// <param name="pn"></param>
        public void TryParseCurrentPageIndex(string pn)
        {
            int temp;
            if (int.TryParse(pn, out temp))
            {
                CurrentPageIndex = temp;
            }
            else
            {
                CurrentPageIndex = 1;
            }
        }

        /// <summary>
        /// 创建页码链接
        /// </summary>
        /// <param name="i">页码</param>
        /// <param name="text">链接文本</param>
        /// <returns></returns>
        private string GetPageLink(int i,string text)
        {
            StringBuilder sb = new StringBuilder();
            string url = UrlFormat.Replace("{n}", i.ToString());
            sb.Append("<a href='").Append(url).Append("'>").Append(text).Append("</a>");
            return sb.ToString();
        }

        /// <summary>
        /// 检查输入参数
        /// </summary>
        private void Check()
        {
            Debug.Assert(PageSize>0);
            Debug.Assert(CurrentPageIndex >= 0);
            Debug.Assert(!string.IsNullOrEmpty(UrlFormat));
        }

        /// <summary>
        ///渲染到前台到得HTML代码
        /// </summary>
        /// <returns></returns>
        public string Render()
        {
            Check();
            StringBuilder sb = new StringBuilder();

double tempCount = TotalCount / PageSize;
int pageCount = (int)Math.Ceiling(tempCount);

            //计算显示的页码数（当总页码大于MaxPagerCount）的起始页码
            int visibleStart = CurrentPageIndex-MaxPagerCount/2;
            if (visibleStart <1)
            {
                visibleStart = 1;
            }

            //计算显示的页码数（当总页码大于MaxPagerCount）的起始页码
            int visibleEnd = visibleStart + MaxPagerCount;
            //显示最多MaxPagerCount条
            //如果算出来的结束页码大于总页码的话则调整为最大页码
            if (visibleEnd >pageCount)
            {
                visibleEnd = pageCount;
            }

            if (CurrentPageIndex > 1)
            {
                sb.Append(GetPageLink(1, "首页"));
                sb.Append(GetPageLink(CurrentPageIndex - 1, "上一页"));
            }
            else
            {
                sb.Append("<span>首页</span>");
                //如果没有上一页了，则只显示一个上一页的文字，没有超链接
                sb.Append("<span>上一页</span>");
            }

            //绘制可视的页码链接
            for (int i = visibleStart; i <= visibleEnd; i++)
            {
                //当前页不是超链接
                if (i == CurrentPageIndex)
                {
                    sb.Append("<span>").Append(i).Append("</span>");
                }
                else
                {
                    sb.Append(GetPageLink(i,i.ToString()));
                }
            }
            if (CurrentPageIndex < pageCount)
            {
                sb.Append(GetPageLink(CurrentPageIndex + 1, "下一页"));
                sb.Append(GetPageLink(pageCount + 1, "末页"));
            }
            else
            {
                sb.Append("<span>下一页</span>");
                sb.Append("<span>末页</span>");
            }
            return sb.ToString();
        }
    }
}

二、UI层代码示例

public partial class 分页测试 : System.Web.UI.Page
    {
        protected string PagerHTML { get; private set; }
        protected void Page_Load(object sender, EventArgs e)
        {
            var pager = new MyPager();
            pager.UrlFormat = "分页测试.aspx?pagenum={n}";
            pager.PageSize = 10;
            pager.TryParseCurrentPageIndex(Request["pagenum"]);
            int startRowIndex = (pager.CurrentPageIndex - 1) * pager.PageSize;

            so_KeywordLogBLL bll = new so_KeywordLogBLL();
            pager.TotalCount = bll.GetTotalCount();
            Repeater1.DataSource = bll.GetPagedData(startRowIndex, startRowIndex + pager.PageSize - 1);
            Repeater1.DataBind();

            PagerHTML = pager.Render();//渲染页码条HTML
        }
    }

三、前台代码

四、加一个CSS更好看

五、再加一个数据访问层的Select代码

public int GetTotalCount()
        {
            string sql = "SELECT count(*) FROM so_KeywordLog";
            return (int)DbHelperSQL.GetSingle(sql);
        }

        public DataSet GetPagedData(int minrownum, int maxrownum)
        {
            string sql = "SELECT * from(SELECT *,(row_number() over(order by Id))-1 rownum FROM so_KeywordLog) t where rownum>=@minrownum and rownum<=@maxrownum";
            SqlParameter[] parameters = { new SqlParameter("@minrownum", SqlDbType.Int, 4), new SqlParameter("@maxrownum", SqlDbType.Int, 4) };
            parameters[0].Value = minrownum;
            parameters[1].Value = maxrownum;
            return DbHelperSQL.Query(sql, parameters);
        }

六、相关分页Select语句（扩展）

1 存储过程
create PROCEDURE GetPageDataOutRowPageCount2
(
@PageIndex int = 1,--当前页数
@PageSize int = 10,--每页大小
@RowCount int output,--总行数(传出参数)
@PageCount int output--总页数(传出参数)
)
AS
begin
DECLARE @sql NVARCHAR(225),@sqlCount NVARCHAR(225)
select @RowCount =COUNT(SID),@PageCount=CEILING((COUNT(SID)+0.0)/@PageSize) FROM Students
SET @sql='SELECT TOP '+str(@PageSize) +' FROM Students where SID not in(select top '+str((@PageIndex-1)*@PageSize) +' SID from Students)'
EXEC(@sql)
end

2 Select语句
select top " + pageSize + " * from Students where SID not in (select top " + (pageIndex - 1) * int.Parse(pageSize) + " SID from Students)
3 Select语句
select * from (select * ,Row_Number()over(order by id) RowNumber from books) t
where t.RowNumber>=11 and t.RowNumber<=20
第n页: (PageIndex-1)*pageSize+1,PageIndex*pageSize

4 ListView 提供的分页不说了