winfrom 使用NPOI导入导出Excel(xls/xlsx)数据到DataTable中

// <summary>
/// Excel某sheet中内容导入到DataTable中
/// 区分xsl和xslx分别处理
/// </summary>
/// <param name="filePath">Excel文件路径,含文件全名</param>
/// <param name="sheetName">此Excel中sheet名</param>
/// <returns></returns>
public DataTable ExcelSheetImportToDataTable(string filePath, string sheetName)
{
             
    DataTable dt = new DataTable();
 
    if (Path.GetExtension(filePath).ToLower() == ".xls".ToLower())
    {//.xls
        #region .xls文件处理:HSSFWorkbook
        try
        {
            using (FileStream file = new FileStream(filePath, FileMode.Open, FileAccess.Read))
            {
 
                hssfworkbook = new HSSFWorkbook(file);
            }
        }
        catch (Exception e)
        {
            throw e;
        }           
 
        ISheet sheet = hssfworkbook.GetSheet(sheetName);
        System.Collections.IEnumerator rows = sheet.GetRowEnumerator();
        HSSFRow headerRow = (HSSFRow)sheet.GetRow(0);               
 
        //一行最后一个方格的编号 即总的列数 
        for (int j = 0; j < (sheet.GetRow(0).LastCellNum); j++)
        {
            //SET EVERY COLUMN NAME
            HSSFCell cell = (HSSFCell)headerRow.GetCell(j);
 
            dt.Columns.Add(cell.ToString());
        }
 
        while (rows.MoveNext())
        {
            IRow row = (HSSFRow)rows.Current;
            DataRow dr = dt.NewRow();
 
            if (row.RowNum == 0) continue;//The firt row is title,no need import
 
            for (int i = 0; i < row.LastCellNum; i++)
            {
                if (i>=dt.Columns.Count)//cell count>column count,then break //每条记录的单元格数量不能大于表格栏位数量 20140213
                {
                    break;
                }
 
                ICell cell = row.GetCell(i);
 
                if ((i==0)&&(string.IsNullOrEmpty(cell.ToString())==true))//每行第一个cell为空,break
                {
                    break;
                }
 
                if (cell == null)
                {
                    dr[i] = null;
                }
                else
                {
                    dr[i] = cell.ToString();
                }
            }
                     
            dt.Rows.Add(dr);
        }
        #endregion
    }
    else
    {//.xlsx
        #region .xlsx文件处理:XSSFWorkbook
        try
        {
            using (FileStream file = new FileStream(filePath, FileMode.Open, FileAccess.Read))
            {
 
                hssfworkbook = new XSSFWorkbook(file);
            }
        }
        catch (Exception e)
        {
            throw e;
        }           
 
        ISheet sheet = hssfworkbook.GetSheet(sheetName);
        System.Collections.IEnumerator rows = sheet.GetRowEnumerator();
        XSSFRow headerRow = (XSSFRow)sheet.GetRow(0);
 
                 
 
        //一行最后一个方格的编号 即总的列数 
        for (int j = 0; j < (sheet.GetRow(0).LastCellNum); j++)
        {
            //SET EVERY COLUMN NAME
            XSSFCell cell = (XSSFCell)headerRow.GetCell(j);
 
            dt.Columns.Add(cell.ToString());
 
        }
 
        while (rows.MoveNext())
        {
            IRow row = (XSSFRow)rows.Current;
            DataRow dr = dt.NewRow();
 
            if (row.RowNum == 0) continue;//The firt row is title,no need import
 
            for (int i = 0; i < row.LastCellNum; i++)
            {
                if (i >= dt.Columns.Count)//cell count>column count,then break //每条记录的单元格数量不能大于表格栏位数量 20140213
                {
                    break;
                }
 
                ICell cell = row.GetCell(i);
 
                if ((i == 0) && (string.IsNullOrEmpty(cell.ToString()) == true))//每行第一个cell为空,break
                {
                    break;
                }
 
                if (cell == null)
                {
                    dr[i] = null;
                }
                else
                {
                    dr[i] = cell.ToString();
                }
            }
            dt.Rows.Add(dr);
        }
        #endregion
    }
    return dt;
}

/// <summary>
       /// NPOI导出Excel，不依赖本地是否装有Excel，导出速度快
       /// </summary>
       /// <param name="dataGridView1">要导出的dataGridView控件</param>
       /// <param name="sheetName">sheet表名</param>
       ///
       public static void ExportToExcel(DataGridView dataGridView1, string sheetName)
       {
           SaveFileDialog fileDialog = new SaveFileDialog();
           fileDialog.Filter = "Excel(97-2003)|*.xls";
           if (fileDialog.ShowDialog() == System.Windows.Forms.DialogResult.Cancel)
           {
               return;
           }
           //不允许dataGridView显示添加行，负责导出时会报最后一行未实例化错误
           dataGridView1.AllowUserToAddRows = false;
           HSSFWorkbook workbook = new HSSFWorkbook();
           ISheet sheet = workbook.CreateSheet(sheetName);
           IRow rowHead = sheet.CreateRow(0);
 
           //填写表头
           for (int i = 0; i < dataGridView1.Columns.Count; i++)
           {
               rowHead.CreateCell(i, CellType.String).SetCellValue(dataGridView1.Columns[i].HeaderText.ToString());
           }
           //填写内容
           for (int i = 0; i < dataGridView1.Rows.Count; i++)
           {
               IRow row = sheet.CreateRow(i + 1);
               for (int j = 0; j < dataGridView1.Columns.Count; j++)
               {
                   row.CreateCell(j, CellType.String).SetCellValue(dataGridView1.Rows[i].Cells[j].Value.ToString());
               }
           }
 
           using (FileStream stream = File.OpenWrite(fileDialog.FileName))
           {
               workbook.Write(stream);
               stream.Close();
           }
           MessageBox.Show("导出数据成功!", "提示", MessageBoxButtons.OK, MessageBoxIcon.Information);
           GC.Collect();
       }