技术文章 > C#高效分页代码(不用存储过程)

C#高效分页代码(不用存储过程)

2017-08-23 17:49

文档管理软件,文档管理系统,知识管理系统,档案管理系统的技术资料:

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)

[code]
csharp
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>“);
}
}
}
}

[/code]