WinForm中DataGridView显示更新数据--人性版

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace UI
{
    public partial class FormStockList : Form
    {
        public FormStockList()
        {
            InitializeComponent();
            this.dgvStockList.AutoGenerateColumns = false;//自动产生列设置为false;
        }

        //加载商品ID的下拉列表的数据源和DGV的数据源.
        private void FormStockList_Load(object sender, EventArgs e)
        {
            //把DataGridView中名为goodsId的下拉列表列取出来,设置重要属性.
            DataGridViewComboBoxColumn col = this.dgvStockList.Columns["goodsId"] as DataGridViewComboBoxColumn;
            col.DataSource = new BLL.GoodsBLL().GetModelList("");
            col.DisplayMember = "Name";
            col.ValueMember = "GoodsId";
            col.DisplayStyle = DataGridViewComboBoxDisplayStyle.Nothing;

            LoadDataByPageIndex();//加载DataGridView的数据源.
        }

        int cellRowIndex;//全局变量,存储单元格行号
        int cellColumnIndex;//全局变量,存储单元格列号
        
        int PreSelectRowIndex;//存储行号,以后用来判断是否换行.
        bool isFirstSelectRow = true;//标识是否给变量PreSelectRowIndex赋过值.没为PreSelectRowIndex赋过值,则为true.
        private void dgvStockList_CellClick(object sender, DataGridViewCellEventArgs e)
        {
            //DataGridView dgv = (DataGridView)sender;
            cellRowIndex = this.dgvStockList.CurrentCell.RowIndex;//为cellRowIndex赋值
            cellColumnIndex = this.dgvStockList.CurrentCell.ColumnIndex;//为cellColumnIndex赋值
            if (isFirstSelectRow)//若isFirstSelectRow为true,说明PreSelectRowIndex是未赋过值
            {
                PreSelectRowIndex = e.RowIndex;//把当前行号赋值给PreSelectRowIndex
                isFirstSelectRow = false;//说明已经给PreSelectRowIndex赋值
            }
            else//如果已经给PreSelectRowIndex赋值
            {
                if (e.RowIndex != PreSelectRowIndex)//当前选的单元格的行号和存储的行号不一样,说明换行了.
                {
                    PreSelectRowIndex = e.RowIndex;//存储新行的行号.
                    SelectionRowChanged();//换行时要执行的方法.可能或重新绑定dgvStockList的数据源.
                    this.dgvStockList.Rows[cellRowIndex].Cells[cellColumnIndex].Selected = true;//针对可能重新绑定dgvStockList的数据源的情况,重新设置当前选中的单元格为重新绑定数据源前用户已选的单元格.
                }
            }
            this.dgvStockList.BeginEdit(true);//dgvStockList_CellClick点击事件会选择一个单元格,BeginEdit让当前单元格可以编辑,能触发dgvStockList_CellBeginEdit事件.
        }

        ////换行时判断是否值有变化,如果有,就把行数据更新到数据库.重新加载数据源.
        private void SelectionRowChanged()
        {
            if (isEdit)//判断该行是否编辑过
            {
                if (temp.GoodsId != stock.GoodsId || temp.SCount != stock.SCount || temp.StockPrice != stock.StockPrice)//判断编辑过后该行的数据是否改变,如果改变了,就更新数据到数据库.
                {
                    new BLL.StockBLL().Update(stock);//把变动后的行数据更新到数据库.                   
                    LoadDataByPageIndex();//重新加载dgvStockList的数据源.
                }
            }
            isEdit = false;//重置isEdit的状态.
            isFirst = true;//重置isFirst的状态.
        }

        Model.Stock stock = null;//存储变动后的行数据的实体对象.
        Model.Stock temp = null;//存储变动前的行数据的实体对象
        bool isFirst = true;//标识是否是第一次编辑该行.
        bool isEdit = false;//标识一行是否被编辑过.如果没有,以后就不用更新行数据到数据库.

        private void dgvStockList_CellBeginEdit(object sender, DataGridViewCellCancelEventArgs e)
        {
            isEdit = true;//标识该行被编辑.
            stock = this.dgvStockList.SelectedRows[0].DataBoundItem as Model.Stock;//把该行的对象用存入变量stock
            if (isFirst)//如果是第一次要开始编辑该行,即该行还没有被编辑过.
            {
                temp = new Model.Stock();//存储该行最初的数据.
                temp.GoodsId = stock.GoodsId;
                temp.SCount = stock.SCount;
                temp.StockPrice = stock.StockPrice;
                isFirst = false;//标识该行不再是第一次被编辑了.
            }
        }
        int pageIndex = 1;//页索引
        int pageCount = 4;//每页显示几条数据
        private void LoadDataByPageIndex()
        {
            this.dgvStockList.DataSource = new BLL.StockBLL().GetStockListByPage(pageIndex, pageCount);
        }//加载dgvStockList的数据.

        //点击上一页
        private void btnPre_Click(object sender, EventArgs e)
        {
            pageIndex--;
            if (pageIndex < 1)
            {
                MessageBox.Show("已经第一页了"); pageIndex++; return;
            }
            LoadDataByPageIndex();
        }

        //点击下一页
        private void btnNext_Click(object sender, EventArgs e)
        {
            pageIndex++;
            if (pageIndex > Model.Save.TPageCount)//Model.Save.TPageCount存的是总的页数.
            {
                MessageBox.Show("已经最后一页了"); pageIndex--; return;
            }
            LoadDataByPageIndex();
        }
    }
}