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不用存储过程的分页实现

2010-08-04 10:34 253 查看
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>");

}

}

}

}
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