private void btnImport_Click(object sender, EventArgs e)        {            DataSet ds = new DataSet();            DataTable dt = null;            OpenFileDialog sflg = new OpenFileDialog();            sflg.Filter = "Excel(*.xls)|*.xls|Excel(*.xlsx)|*.xlsx";            if (sflg.ShowDialog() == System.Windows.Forms.DialogResult.Cancel)            {                return;            }            FileStream fs = new FileStream(sflg.FileName, FileMode.Open, FileAccess.Read);            NPOI.HSSF.UserModel.HSSFWorkbook book = new NPOI.HSSF.UserModel.HSSFWorkbook(fs);            int sheetCount = book.NumberOfSheets;            for (int sheetIndex = 0; sheetIndex < sheetCount; sheetIndex++)            {                NPOI.SS.UserModel.ISheet sheet = book.GetSheetAt(sheetIndex);                if (sheet == null) continue;                                NPOI.SS.UserModel.IRow row = sheet.GetRow(0);                if (row == null) continue;                int firstCellNum = row.FirstCellNum;                int lastCellNum = row.LastCellNum;                if (firstCellNum == lastCellNum) continue;                dt = new DataTable(sheet.SheetName);                for (int i = firstCellNum; i < lastCellNum; i++)                {                    dt.Columns.Add(row.GetCell(i).StringCellValue, typeof(string));                }                for (int i = 1; i <= sheet.LastRowNum; i++)                {                    DataRow newRow = dt.Rows.Add();                    for (int j = firstCellNum; j < lastCellNum; j++)                    {                        newRow[j] = sheet.GetRow(i).GetCell(j).StringCellValue;                    }                }                ds.Tables.Add(dt);            }                   }        private void btnExport_Click(object sender, EventArgs e)        {            SaveFileDialog sflg = new SaveFileDialog();            sflg.Filter = "Excel(*.xls)|*.xls|Excel(*.xlsx)|*.xlsx";            if (sflg.ShowDialog() == System.Windows.Forms.DialogResult.Cancel)            {                return;            }            //this.gridView1.ExportToXls(sflg.FileName);            //NPOI.xs book = new NPOI.HSSF.UserModel.HSSFWorkbook();            NPOI.SS.UserModel.IWorkbook book = null;            if (sflg.FilterIndex == 1)            {                book = new NPOI.HSSF.UserModel.HSSFWorkbook();            }            else            {                book = new NPOI.XSSF.UserModel.XSSFWorkbook();            }            NPOI.SS.UserModel.ISheet sheet = book.CreateSheet("test_001");            // 添加表头            NPOI.SS.UserModel.IRow row = sheet.CreateRow(0);            int index = 0;            foreach (GridColumn item in this.gridView1.Columns)            {                if (item.Visible)                {                    NPOI.SS.UserModel.ICell cell = row.CreateCell(index);                    cell.SetCellType(NPOI.SS.UserModel.CellType.String);                                        cell.SetCellValue(item.Caption);                    index++;                }            }            // 添加数据                       for (int i = 0; i < this.gridView1.DataRowCount; i++)            {                index = 0;                row = sheet.CreateRow(i + 1);                foreach (GridColumn item in this.gridView1.Columns)                {                    if (item.Visible)                    {                        NPOI.SS.UserModel.ICell cell = row.CreateCell(index);                        cell.SetCellType(NPOI.SS.UserModel.CellType.String);                        cell.SetCellValue(this.gridView1.GetRowCellValue(i, item).ToString());                        index++;                    }                }            }            // 写入             System.IO.MemoryStream ms = new System.IO.MemoryStream();            book.Write(ms);            book = null;            using (FileStream fs = new FileStream(sflg.FileName, FileMode.Create, FileAccess.Write))            {                byte[] data =http://www.mamicode.com/ ms.ToArray();                fs.Write(data, 0, data.Length);                fs.Flush();            }            ms.Close();            ms.Dispose();        }