在asp.net 中,DataGrid自定义分页是个常见的问题.在项目中,很多人采用aspnetpage控件结合高效SQL存储过程分页.本文将采用简单、易懂的方式来实现项目中的分页要求.项目中数据表记录为80000,0条.分页速度很快的.本人对照了下,在如此记录情况下,使用DataGrid自带的分页功能,在切换到下一页时,cpu有使用100% 的过程;而使用本文的方法自定义分页,cpu使用只有百分之几哦.....
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 WS.Webs
{
/**//// <summary>
/// WebForm1 的摘要说明。
/// </summary>
public class WebForm1 : System.Web.UI.Page
{
protected System.Web.UI.WebControls.DataList datalist1;
protected System.Web.UI.WebControls.Label LPageCount;
protected System.Web.UI.WebControls.Label LRecordCount;
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.Label LCurrentPage;
protected System.Web.UI.WebControls.TextBox gotoPage;
//自定义分页码记录
const int PageSize=20;
int PageCount,RecCount,CurrentPage,Pages,JumpPage;//定义几个保存分页参数变量
private void Page_Load(object sender, System.EventArgs e)
{
if(!Page.IsPostBack)
{
RecCount = Calc();//通过Calc()函数获取总记录数
PageCount = RecCount/PageSize + OverPage();//计算总页数(加上OverPage()函数防止有余数造成显示数据不完整)
ViewState["PageCounts"] = RecCount/PageSize - ModPage();//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["PageIndex"] = 0;//保存一个为0的页面索引值到ViewState
ViewState["JumpPages"] = PageCount;//保存PageCount到ViewState,跳页时判断用户输入数是否超出页码范围
//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;
TDataBind();//调用数据绑定函数TDataBind()进行数据绑定运算
}
}
//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 fdcproject",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["DSN2"]);
MyConnection.Open();
return MyConnection;
}
private void TDataBind()
{
CurrentPage = (int)ViewState["PageIndex"];//从ViewState中读取页码值保存到CurrentPage变量中进行按钮失效运算
Pages = (int)ViewState["PageCounts"];//从ViewState中读取总页参数进行按钮失效运算
//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 fdcproject where projid not in(select top "+PageSize*CurrentPage+" projid from fdcproject order by projid asc) order by projid 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();
}
Web 窗体设计器生成的代码#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.Click += new System.EventHandler(this.Page_OnClick);
this.Prevpage.Click += new System.EventHandler(this.Page_OnClick);
this.Nextpage.Click += new System.EventHandler(this.Page_OnClick);
this.Lastpage.Click += new System.EventHandler(this.Page_OnClick);
this.gotoPage.TextChanged += new System.EventHandler(this.gotoPage_TextChanged);
this.Load += new System.EventHandler(this.Page_Load);
}
#endregion
private void gotoPage_TextChanged(object sender, System.EventArgs e)
{
try
{
JumpPage = (int)ViewState["JumpPages"];//从ViewState中读取可用页数值保存到JumpPage变量中
//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
{
int InputPage = Int32.Parse(gotoPage.Text.ToString()) - 1;//转换用户输入值保存在int型InputPage变量中
ViewState["PageIndex"] = InputPage;//写入InputPage值到ViewState["PageIndex"]中
TDataBind();//调用数据绑定函数TDataBind()再次进行数据绑定运算
}
}
//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>");
}
}
private void Page_OnClick(object sender, System.EventArgs e)
{
CurrentPage = (int)ViewState["PageIndex"];//从ViewState中读取页码值保存到CurrentPage变量中进行参数运算
Pages = (int)ViewState["PageCounts"];//从ViewState中读取总页参数运算
string cmd = ((LinkButton)sender).CommandName;
switch(cmd)//筛选CommandName
{
case "next":
CurrentPage++;
break;
case "prev":
CurrentPage--;
break;
case "last":
CurrentPage = Pages;
break;
default:
CurrentPage = 0;
break;
}
ViewState["PageIndex"] = CurrentPage;//将运算后的CurrentPage变量再次保存至ViewState
TDataBind();//调用数据绑定函数TDataBind()
}
}
}