C#高效分页代码(不用存储过程)

最新推荐文章于 2022-04-28 18:15:00 发布

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首先创建一张表(要求ID自动编号)：

create table redheadedfile 
( 
id int identity(1,1), 
filenames nvarchar(50), 
senduser nvarchar(50), 
primary key(id) 
)

然后我们写入50万条记录：

declare @i int 
set @i=1 
while @i<=500000 
begin 
insert into redheadedfile(filenames,senduser) values("高效分页算法测试数据" + str(i) ,"北京联高软件开发有限公司") 
set @i=@i+1 
end 
GO

用Microsoft Visual Studio .NET 2005创建一张WebForm网页。
前台代码片段如下(webform8.aspx)：

<%@ Page language="c#" Codebehind="WebForm8.aspx.cs" AutoEventWireup="false" Inherits="WebApplication6.WebForm8" %> 
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN" > 
<HTML> 
<HEAD> 
<title>WebForm8</title> 
<meta content="Microsoft Visual Studio .NET 7.1" name="GENERATOR"> 
<meta content="C#" name="CODE_LANGUAGE"> 
<meta content="javascript" name="vs_defaultClientScript"> 
<meta content="http://schemas.microsoft.com/intellisense/ie5" name="vs_targetSchema"> 
</HEAD> 
<body MS_POSITIONING="GridLayout"> 
<form id="Form1" method="post" runat="server"> 
<asp:datalist id="datalist1" AlternatingItemStyle-BackColor="#f3f3f3" Width="100%" CellSpacing="0" CellPadding="0" Runat="server"> 
<ItemTemplate> 
<table width="100%" border="0" cellspacing="0" cellpadding="0"> 
<tr> 
<td width="30%" align="center"><%#DataBinder.Eval(Container.DataItem,"filenames")%></td> 
<td width="30%" align="center"><%#DataBinder.Eval(Container.DataItem,"senduser")%></td> 
<td width="30%" align="center"><%#DataBinder.Eval(Container.DataItem,"id")%></td> 
</tr> 
</table> 
</ItemTemplate> 
</asp:datalist> 
<div align="center">共<asp:label id="LPageCount" Runat="server" ForeColor="#ff0000"></asp:label>页/共 
<asp:label id="LRecordCount" Runat="server" ForeColor="#ff0000"></asp:label>记录 
<asp:linkbutton id="Fistpage" Runat="server" CommandName="0">首页</asp:linkbutton> 
<asp:linkbutton id="Prevpage" Runat="server" CommandName="prev">上一页</asp:linkbutton> 
<asp:linkbutton id="Nextpage" Runat="server" CommandName="next">下一页</asp:linkbutton> 
<asp:linkbutton id="Lastpage" Runat="server" CommandName="last">尾页</asp:linkbutton> 
当前第<asp:label id="LCurrentPage" Runat="server" ForeColor="#ff0000"></asp:label>页 
跳页<asp:TextBox ID="gotoPage" Runat="server" Width="30px" MaxLength="5" AutoPostBack="True"></asp:TextBox> 
</div> 
</form> 
</body> 
</HTML>

后台代码片段如下(webform8.aspx.cs)

> 纯文本方式> 拷贝到裁剪板> 打印

using System;   
using System.Collections;   
using System.ComponentModel;   
using System.Data;   
using System.Drawing;   
using System.Web;   
using System.Web.SessionState;   
using System.Web.UI;   
using System.Web.UI.WebControls;   
using System.Web.UI.HtmlControls;   
using System.Data.SqlClient;   
using System.Configuration;   
namespace WebApplication6   
{   
    /// <summary>   
    /// WebForm8 的摘要说明。   
    /// </summary>   
    public class WebForm8 : System.Web.UI.Page   
    {   
        protected System.Web.UI.WebControls.LinkButton Fistpage;   
        protected System.Web.UI.WebControls.LinkButton Prevpage;   
        protected System.Web.UI.WebControls.LinkButton Nextpage;   
        protected System.Web.UI.WebControls.LinkButton Lastpage;   
        protected System.Web.UI.WebControls.DataList datalist1;   
        protected System.Web.UI.WebControls.DropDownList mydroplist;   
        protected System.Web.UI.WebControls.Label LPageCount;   
        protected System.Web.UI.WebControls.Label LRecordCount;   
        protected System.Web.UI.WebControls.Label LCurrentPage;   
        protected System.Web.UI.WebControls.TextBox gotoPage;   
        //定义每页显示记录   
        const int PageSize = 20;   
        //定义几个保存分页参数变量   
        int PageCount, RecCount, CurrentPage, Pages, JumpPage;   
        private void Page_Load(object sender, System.EventArgs e)   
        {   
            if (!IsPostBack)   
            {   
                //通过Calc()函数获取总记录数   
                RecCount = Calc();   
                //计算总页数（加上OverPage()函数防止有余数造成显示数据不完整）   
                PageCount = RecCount / PageSize + OverPage();   
                //保存总页参数到ViewState（减去ModPage()函数防止SQL语句执行时溢出查询范围，可以用存储过程分页算法来理解这句）   
                ViewState["PageCounts"] = RecCount / PageSize - ModPage();   
                //保存一个为0的页面索引值到ViewState   
                ViewState["PageIndex"] = 0;   
                //保存PageCount到ViewState，跳页时判断用户输入数是否超出页码范围   
                ViewState["JumpPages"] = PageCount;   
                //显示LPageCount、LRecordCount的状态   
                LPageCount.Text = PageCount.ToString();   
                LRecordCount.Text = RecCount.ToString();   
                //判断跳页文本框失效   
                if (RecCount <= 20)   
                {   
                    gotoPage.Enabled = false;   
                }   
                //调用数据绑定函数TDataBind()进行数据绑定运算   
                TDataBind();   
            }   
        }   
        //计算余页   
        public int OverPage()   
        {   
            int pages = 0;   
            if (RecCount % PageSize != 0)   
                pages = 1;   
            else  
                pages = 0;   
            return pages;   
        }   
        //计算余页，防止SQL语句执行时溢出查询范围   
        public int ModPage()   
        {   
            int pages = 0;   
            if (RecCount % PageSize == 0 && RecCount != 0)   
                pages = 1;   
            else  
                pages = 0;   
            return pages;   
        }   
        // 计算总记录的静态函数   
        // 本人在这里使用静态函数的理由是：如果引用的是静态数据或静态函数，   
        // 连接器会优化生成代码，去掉动态重定位项（对海量数据表分页效果更明显）。   
        // 希望大家给予意见、如有不正确的地方望指正。   
        public static int Calc()   
        {   
            int RecordCount = 0;   
            SqlCommand MyCmd = new SqlCommand("select count(*) as co from redheadedfile", MyCon());   
            SqlDataReader dr = MyCmd.ExecuteReader();   
            if (dr.Read())   
                RecordCount = Int32.Parse(dr["co"].ToString());   
            MyCmd.Connection.Close();   
            return RecordCount;   
        }   
        //数据库连接语句（从Web.Config中获取）   
        public static SqlConnection MyCon()   
        {   
            SqlConnection MyConnection = new SqlConnection(ConfigurationSettings.AppSettings["DSN"]);   
            MyConnection.Open();   
            return MyConnection;   
        }   
        //对四个按钮（首页、上一页、下一页、尾页）返回的CommandName值进行操作   
        private void Page_OnClick(object sender, CommandEventArgs e)   
        {   
            //从ViewState中读取页码值保存到CurrentPage变量中进行参数运算   
            CurrentPage = (int)ViewState["PageIndex"];   
            //从ViewState中读取总页参数运算   
            Pages = (int)ViewState["PageCounts"];   
            string cmd = e.CommandName;   
            //筛选CommandName   
            switch (cmd)   
            {   
                case "next":   
                    CurrentPage++;   
                    break;   
                case "prev":   
                    CurrentPage--;   
                    break;   
                case "last":   
                    CurrentPage = Pages;   
                    break;   
                default:   
                    CurrentPage = 0;   
                    break;   
            }   
            //将运算后的CurrentPage变量再次保存至ViewState   
            ViewState["PageIndex"] = CurrentPage;   
            //调用数据绑定函数TDataBind()   
            TDataBind();   
        }   
        private void TDataBind()   
        {   
            //从ViewState中读取页码值保存到CurrentPage变量中进行按钮失效运算   
            CurrentPage = (int)ViewState["PageIndex"];   
            //从ViewState中读取总页参数进行按钮失效运算   
            Pages = (int)ViewState["PageCounts"];   
            //判断四个按钮（首页、上一页、下一页、尾页）状态   
            if (CurrentPage + 1 > 1)   
            {   
                Fistpage.Enabled = true;   
                Prevpage.Enabled = true;   
            }   
            else  
            {   
                Fistpage.Enabled = false;   
                Prevpage.Enabled = false;   
            }   
            if (CurrentPage == Pages)   
            {   
                Nextpage.Enabled = false;   
                Lastpage.Enabled = false;   
            }   
            else  
            {   
                Nextpage.Enabled = true;   
                Lastpage.Enabled = true;   
            }   
            //数据绑定到DataList控件   
            DataSet ds = new DataSet();   
            //核心SQL语句，进行查询运算（决定了分页的效率:)）   
            SqlDataAdapter MyAdapter = new SqlDataAdapter("Select Top " + PageSize + " * from redheadedfile where id not in(select top " + PageSize * CurrentPage + " id from redheadedfile order by id asc) order by id asc", MyCon());   
            MyAdapter.Fill(ds, "news");   
            datalist1.DataSource = ds.Tables["news"].DefaultView;   
            datalist1.DataBind();   
            //显示Label控件LCurrentPaget和文本框控件gotoPage状态   
            LCurrentPage.Text = (CurrentPage + 1).ToString();   
            gotoPage.Text = (CurrentPage + 1).ToString();   
            //释放SqlDataAdapter   
            MyAdapter.Dispose();   
        }  
        #region Web 窗体设计器生成的代码   
        override protected void OnInit(EventArgs e)   
        {   
            //   
            // CODEGEN: 该调用是 ASP.NET Web 窗体设计器所必需的。   
            //   
            InitializeComponent();   
            base.OnInit(e);   
        }   
        /// <summary>   
        /// 设计器支持所需的方法 - 不要使用代码编辑器修改   
        /// 此方法的内容。   
        /// </summary>   
        private void InitializeComponent()   
        {   
            this.Fistpage.Command += new System.Web.UI.WebControls.CommandEventHandler(this.Page_OnClick);   
            this.Prevpage.Command += new System.Web.UI.WebControls.CommandEventHandler(this.Page_OnClick);   
            this.Nextpage.Command += new System.Web.UI.WebControls.CommandEventHandler(this.Page_OnClick);   
            this.Lastpage.Command += new System.Web.UI.WebControls.CommandEventHandler(this.Page_OnClick);   
            this.gotoPage.TextChanged += new System.EventHandler(this.gotoPage_TextChanged);   
            this.Load += new System.EventHandler(this.Page_Load);   
        }  
        #endregion   
        //跳页代码   
        private void gotoPage_TextChanged(object sender, System.EventArgs e)   
        {   
            try  
            {   
                //从ViewState中读取可用页数值保存到JumpPage变量中   
                JumpPage = (int)ViewState["JumpPages"];   
                //判断用户输入值是否超过可用页数范围值   
                if (Int32.Parse(gotoPage.Text) > JumpPage || Int32.Parse(gotoPage.Text) <= 0)   
                {   
                    Response.Write("<script>alert("页码范围越界！");location.href="WebForm8.aspx"</script>");   
                }   
                else  
                {   
                    //转换用户输入值保存在int型InputPage变量中   
                    int InputPage = Int32.Parse(gotoPage.Text.ToString()) - 1;   
                    //写入InputPage值到ViewState["PageIndex"]中   
                    ViewState["PageIndex"] = InputPage;   
                    //调用数据绑定函数TDataBind()再次进行数据绑定运算   
                    TDataBind();   
                }   
            }   
            //捕获由用户输入不正确数据类型时造成的异常   
            catch (Exception eXP)   
            {   
                Response.Write("<script>alert("" + exp.Message + "");location.href="WebForm8.aspx"</script>");   
            }   
        }   
    }   
}