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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"> </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) |
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>"); } } }} |
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原文地址：http://www.cnblogs.com/hzhhhbb/p/4910422.html
