NOPI操作EXCEL导入导出

        private void btnOutput_Click(object sender, EventArgs e)
        {
            List<MODEL.Classes> list = cm.GetClassInfo(false);    //获取对象数据集合
            HSSFWorkbook workbook=new HSSFWorkbook ();    //新建Excel工作表
            HSSFSheet sheet=workbook.CreateSheet("classes");   //在工作文档中新建页
            for(int i=0;i<list.Count;i++)     //遍历lis对象数据集合
            {
                HSSFRow row=sheet.CreateRow(i);    //在页中创建行
                HSSFCell cell1=row.CreateCell(0);    //在行中创建列
                cell1.SetCellValue(list[i].CID);     //给列字段赋值
                HSSFCell cell2=row.CreateCell(1);
                cell2.SetCellValue(list[i].CName);
                HSSFCell cell3=row.CreateCell(2);
                cell3.SetCellValue(list[i].CCount);
                HSSFCell cell4=row.CreateCell(3);
                cell4.SetCellValue(list[i].CImg);
                HSSFCell cell5=row.CreateCell(4);
                cell5.SetCellValue(list[i].CIsDel);
                HSSFCell cell6=row.CreateCell(5);
                cell6.SetCellValue(list[i].CAddTime);
                HSSFDataFormat date = workbook.CreateDataFormat();    //为工作表创建日期格式
                HSSFCellStyle style = workbook.CreateCellStyle();     //为工作表创建单元格格式
                style.DataFormat = date.GetFormat("yyyy-mm-dd hh-mm-ss");   //将日期格式赋值到单元格格式中
                cell6.CellStyle = style;   //设置具体单元格格式为已定义的日期格式
            }
            using(FileStream fs=new FileStream (txtOutPut.Text.Trim(),FileMode.Create))    //获取路径并创建对应文件
            {
                workbook.Write(fs);      //写入对应文件
                MessageBox.Show("写入成功");
            }
        }

        private void btnInput_Click(object sender, EventArgs e)
        {
            List<MODEL.Classes> list = new List<MODEL.Classes>();      //实例化集合对象接受数据
            using(FileStream fs=new FileStream (txtInput.Text.Trim(),FileMode.Open))    //打开对应文件
            {
                HSSFWorkbook workbook = new HSSFWorkbook(fs);   //读取工作表内容
                HSSFSheet sheet = workbook.GetSheet("classes");   //读取页内容
                for(int i=sheet.FirstRowNum;i<sheet.LastRowNum;i++)    //遍历行
                {
                    MODEL.Classes temp = new MODEL.Classes();    //实例化对象接受数据
                    HSSFRow row = sheet.GetRow(i);      //读取行内容
                    temp.CID = (int)row.GetCell(0).NumericCellValue;
                    temp.CName = row.GetCell(1).StringCellValue;
                    temp.CCount =(int) row.GetCell(2).NumericCellValue;
                    temp.CImg = row.GetCell(3).StringCellValue;
                    temp.CIsDel = row.GetCell(4).BooleanCellValue;
                    temp.CAddTime = row.GetCell(5).DateCellValue;
                    list.Add(temp);
                }
            }
            this.dgvClassList.DataSource = list;
        }