ASP.NET学习之分页数据绑定_GridView

前台页面:

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="GridView自定义真分页.aspx.cs" Inherits="分页显示数据.GridView自定义真分页" %>

<!DOCTYPE html>

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
    <title></title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
        <asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False">
           <Columns>
                <asp:TemplateField HeaderText="用户ID">
                    <ItemTemplate><%#Eval("Uid") %></ItemTemplate>
                </asp:TemplateField>
                <asp:TemplateField HeaderText="主题">
                    <ItemTemplate><%#Eval("Subject") %></ItemTemplate>
                </asp:TemplateField>
                <asp:TemplateField HeaderText="内容">
                    <ItemTemplate><%#Eval("Content") %></ItemTemplate>
                </asp:TemplateField>
            </Columns>
        </asp:GridView>
        总共有<asp:Label ID="TRecordCount" runat="server"></asp:Label>条数据
        每页记录<asp:Label ID="TPageSize" runat="server"></asp:Label>条数据
        共有<asp:Label ID="TPageCount" runat="server"></asp:Label>页数据
        当前是第<asp:Label ID="numberPage" runat="server"></asp:Label><asp:LinkButton ID="First" runat="server" CommandName="first" OnCommand="First_Command">首页</asp:LinkButton>
        <asp:LinkButton ID="Pre" runat="server" CommandName="pre" OnCommand="First_Command">上一页</asp:LinkButton>
        <asp:LinkButton ID="Next" runat="server" CommandName="next" OnCommand="First_Command">下一页</asp:LinkButton>
        <asp:LinkButton ID="Last" runat="server" CommandName="last" OnCommand="First_Command">尾页</asp:LinkButton>
        直接跳到第<asp:DropDownList ID="ddl" runat="server" OnSelectedIndexChanged="ddl_SelectedIndexChanged">
            </asp:DropDownList></div>
    </form>
</body>
</html>

后台代码:

using System;
using System.Collections.Generic;
using System.Data;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Configuration;
using System.Data.SqlClient;
using System.Text;

namespace 分页显示数据
{
    /// <summary>
    /// GridView自定义真分页
    /// 准备工作:
    /// 1、前台准备
    /// 1)添加一个GridView组件。可以根据需求设置行列。也可以设置GridView1.AutoGenerateColumns = true;来默认生成行列
    /// 2)把需要的组件都准备好【显示总页数、总记录数、每页显示的数据数、当前页数、上一页、下一页、首页、尾页、下拉选项】
    /// 
    /// 2、后台准备
    /// 1)申明四个变量:用来存储总页数、总记录数、每页数据数、当前页数
    /// 2)定义一个方法:用来获取所有数据,通过SQLDataAdapter将数据填充到DataSet中
    /// 3)在程序第一次加载的时候,给总页数、总记录数、每页显示的数据数、当前页数和下拉选项赋值
    /// 4)写一个方法来拼接【查询每个页面要显示的数据】的SQl语句
    /// 5)写一个方法:在该方法中通过调用Sql语句拼接的方法,得到每个页面要显示的数据
    /// 6)写一个方法:用来实现当页码发生改变时,显示每页的数据【主要是数据绑定、按钮是否可用的设置】
    /// 7)首页、上一页、下一页、尾页点击事件的实现方法:四个用一个点击方法
    /// 8)给下拉选项的选项改变写事件
    /// 
    /// </summary>
    public partial class GridView自定义真分页 : System.Web.UI.Page
    {

        private int PageCount;     //总页数
        private int RecordCount;   //总记录数
        private int PageSize=5;    //初始化每页的数据量//每页显示多少条数据
        private int CurrentPageIndex;  //当前是第几页
        string strConnection = ConfigurationManager.ConnectionStrings["MyDB"].ToString();  //获得数据库连接字符串
        /// <summary>
        /// 加载页面
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        protected void Page_Load(object sender, EventArgs e)
        {
            #region 第一次加载
            if (!IsPostBack)
            {  //第一次加载:在第一加载时初始化的数据,在之后的操作中都不会改变
                //初始化PageCount、RecordCount、PageSize
                DataSet ds=GetDataSet();
                RecordCount = ds.Tables[0].Rows.Count;   //得到数据的总记录数
                //给页数赋值
                if (RecordCount % PageSize == 0)
                {  //如果总记录数取余每页显示的条数,结果是0,说明刚好除尽。
                    PageCount = RecordCount / PageSize;
                }
                else
                {  //否则没有除尽
                    PageCount = RecordCount / PageSize + 1;
                }

                CurrentPageIndex = 1;  //当前页

                //用lable记下这几个值,就不需要每次都计算一遍了。直接用就可以了
                TRecordCount.Text = RecordCount.ToString();
                TPageCount.Text = PageCount.ToString();
                TPageSize.Text = PageSize.ToString();
                numberPage.Text = CurrentPageIndex.ToString();

                //给ddl组件[下拉组件]绑定数据
                for (int i = 1; i <= PageCount; i++)
                {
                    ddl.Items.Add(i.ToString());
                } 
            //根据页码展示数据
            ShowData();
            }
            #endregion
            CurrentPageIndex = int.Parse(numberPage.Text.ToString());   //得到当前页码,赋给CurrentPageIndex
            PageCount = int.Parse(TPageCount.Text.ToString());   //获得页码总数
        }

        /// <summary>
        /// 得到查询的表的所有数据,通过SQLDataAdapter填充到DataSet中【方便给四个主要变量赋值】
        /// </summary>
        public DataSet GetDataSet()
        {
            DataSet ds = new DataSet();
            using (SqlConnection sqlConn = new SqlConnection(strConnection))
            { //创建数据库链接对象
                string sqlStr = "select Uid,Subject,Content from tb_leaveWord";  //SQL查询语句
                SqlDataAdapter sda = new SqlDataAdapter(sqlStr, sqlConn);
                //将满足条件的数据填充到ds集合中
                sda.Fill(ds);
            }
            return ds;
        }

        /// <summary>
        /// 得到每页的数据
        /// </summary>
        /// <returns></returns>
        public DataSet GetEveryPageData()
        {
            DataSet ds = new DataSet();
            using (SqlConnection sqlconn = new SqlConnection(strConnection))
            {            
               string str = GetSqlStr();
               SqlDataAdapter sda = new SqlDataAdapter(str, sqlconn);
               sda.Fill(ds);
            }
            return ds;
        }

        /// <summary>
        /// 得到Sql语句
        /// </summary>
        /// <returns></returns>
        public string GetSqlStr()
        {
            #region 方法一:
            StringBuilder sb = new StringBuilder();
            sb.Append("select top(");
            sb.Append(PageSize.ToString());
            sb.Append(")Uid,Subject,Content from tb_LeaveWord where ID not in((select top(");
            sb.Append((PageSize * (CurrentPageIndex - 1)).ToString());
            sb.Append(")ID from tb_LeaveWord))");
            return sb.ToString(); 
            #endregion

            #region 方法二:
            //StringBuilder sb = new StringBuilder();
            //sb.AppendFormat("select top({0})Uid,Subject,Content from tb_LeaveWord where ID not in((select top({1})ID from tb_LeaveWord))", PageSize.ToString(), (PageSize * (CurrentPageIndex - 1)).ToString());
            //return sb.ToString();
            #endregion

            #region 方法三:不建议这么写
            //string str = "select top(" + PageSize.ToString() + ")Uid,Subject,Content from tb_LeaveWord where ID not in((select top(" + (PageSize * (CurrentPageIndex - 1)).ToString() + ")ID from tb_LeaveWord))";
            #endregion 


        }

        /// <summary>
        /// 显示选定页码该显示的数据
        /// </summary>
        public void ShowData()
        {
            DataSet Sds = GetEveryPageData();
            GridView1.DataSource = Sds;
            //先要让数据按照自己给定的行列显示数据,那就把该属性关掉【这样就不会出现默认生成的行列了】
            //GridView1.AutoGenerateColumns = true;
            GridView1.DataBind();
            numberPage.Text = CurrentPageIndex.ToString();
            ddl.SelectedValue = CurrentPageIndex.ToString();   //下拉菜单选择中的值

            //设置按钮的可用性
            if(CurrentPageIndex==1){
                First.Enabled = false;
                Pre.Enabled = false;
            }
            else
            {
                First.Enabled = true;
                Pre.Enabled = true;
            }

            if (CurrentPageIndex==PageCount)
            {
                Next.Enabled = false;
                Last.Enabled = false;
            }
            else
            {
                Next.Enabled = true;
                Last.Enabled = true;
            }
        }

        /// <summary>
        /// 下拉框选项改变事件
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        protected void ddl_SelectedIndexChanged(object sender, EventArgs e)
        {
            string num = ddl.SelectedValue;
            CurrentPageIndex = int.Parse(num);
            ShowData();
        }

        /// <summary>
        /// 写首页、上一页、下一页、尾页点击事件的实现方法
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        protected void First_Command(object sender, CommandEventArgs e)
        {
            string result = e.CommandName;
            switch(result){
                case "first":
                    CurrentPageIndex = 1;
                    break;
                case "pre":
                    CurrentPageIndex--;
                    break;
                case "next":
                    CurrentPageIndex++;
                    break;
                case "last":
                    CurrentPageIndex = PageCount;
                    break;
            }
            ShowData();//数据展示
        }

    }
}
原文地址:https://www.cnblogs.com/Yisijun/p/4592111.html