C#DataGridView实现分页显示

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.Data.SqlClient;

namespace dgvCategories
{
    public partial class Form1 : Form
    {
        int _iPageSize = 0;       //每页显示行数
        int _iTotalRecords = 0;    //总记录数
        int _iPageCount = 0;      //页数＝总记录数/每页显示行数
        int _iPageCurrent = 0;    //当前页号
        int _iCurrent = 0;        //当前记录行
        DataSet _ds = new DataSet();
        DataTable _dtCategories = new DataTable();

        public Form1()
        {
            InitializeComponent();
        }

        private void InitDataSet()
        {
            _iPageSize = 20;  //每页显示20行
            _iTotalRecords = _dtCategories.Rows.Count; //表的总行数
            _iPageCount = _iTotalRecords / _iPageSize; //总页数

            if (_iTotalRecords % _iPageSize > 0) //如果不是整除，
            {
                _iPageCount++;//不满20行的也作为一页来显示
            }

            _iPageCurrent = 1;  //当前第1页
            _iCurrent = 0;      //当前第0行

            LoadData();
        }

        private void LoadData()
        {
            int iBeginPos = 0;   //当前页面开始记录行
            int iEndPos = 0;     //当前页面结束记录行

            DataTable dtTemp = _dtCategories.Clone();  //克隆表的结构

            if (_iPageCurrent == _iPageCount) //如果当前页是最后一页
            {
                iEndPos = _iTotalRecords;
            }
            else//当前页面结束位置=页面大小*当前页码
            {
                iEndPos = _iPageSize * _iPageCurrent;
            }

            iBeginPos = _iCurrent; //当前记录行号

            txtPageCount.Text = Convert.ToString(_iPageCount); //显示总页数
            txtCurentPage.Text = Convert.ToString(_iPageCurrent); //显示当前第一页

            //从元数据表复制数据
            for (int i = iBeginPos; i < iEndPos; i++ )
            {
                dtTemp.ImportRow(_dtCategories.Rows[i]);
                _iCurrent++;
            }

            dgvCategories.DataSource = bdsCategories;
            bdnCategories.BindingSource = bdsCategories;
            bdsCategories.DataSource = dtTemp;
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            string strConnectionString = "server=localhost;database=NorthWind;" +
                "uid=sa;pwd=tianshi520;";
            SqlConnection sqlConn = new SqlConnection(strConnectionString);
            sqlConn.Open();

            string strSql = "select * from orders";
            SqlDataAdapter sda = new SqlDataAdapter(strSql, sqlConn);

            sda.Fill(_ds, "Categories");
            _dtCategories = _ds.Tables["Categories"];
            sqlConn.Close();

            InitDataSet();
        }

        private void bdnCategories_ItemClicked(object sender, ToolStripItemClickedEventArgs e)
        {
            if (e.ClickedItem.Text == "关闭")
            {
                this.Close();
            }
            else if (e.ClickedItem.Text == "下一页")
            {
                _iPageCurrent++;//页数加1
                if (_iPageCurrent > _iPageCount)//如果当前页码>最大页数
                {
                    MessageBox.Show("已经是最后一页，请点击“上一页”查看！");
                    return;
                }

                _iCurrent = _iPageSize * (_iPageCurrent - 1);//当前行号
                LoadData();
            }
            else if (e.ClickedItem.Text == "上一页")
            {
                _iPageCurrent--;
                if (_iPageCurrent <= 0)
                {
                    MessageBox.Show("当前已经是第一页，请点击下一页查看!");
                    return;
                }
                _iCurrent = _iPageSize * (_iPageCurrent - 1);
                LoadData();
            }
        }
    }
}