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();            }        }    }}