在C#中使用NPOI2.0操作Excel2003和Excel2007

Excel2003：

#region Excel2003  
    /// <summary>  
    /// 将Excel檔案中的資料讀出到DataTable中(xls)  
    /// </summary>  
    /// <param name="file"></param>  
    /// <returns></returns>  
    public static DataTable ExcelToTableForXLS(string file)  
    {  
        DataTable dt = new DataTable();  
        using (FileStream fs = new FileStream(file, FileMode.Open, FileAccess.Read))  
        {  
            XLS.HSSFWorkbook hssfworkbook = new XLS.HSSFWorkbook(fs);  
            ISheet sheet = hssfworkbook.GetSheetAt(0);  
      
            //表頭  
            IRow header = sheet.GetRow(sheet.FirstRowNum);  
            List<int> columns = new List<int>();  
            for (int i = 0; i < header.LastCellNum; i++)  
            {  
                object obj = GetValueTypeForXLS(header.GetCell(i) as XLS.HSSFCell);  
                if (obj == null || obj.ToString() == string.Empty)  
                {  
                    dt.Columns.Add(new DataColumn("Columns" + i.ToString()));  
                    //continue;  
                }  
                else  
                    dt.Columns.Add(new DataColumn(obj.ToString()));  
                columns.Add(i);  
            }  
            //資料  
            for (int i = sheet.FirstRowNum + 1; i <= sheet.LastRowNum; i++)  
            {  
                DataRow dr = dt.NewRow();  
                bool hasValue = false;  
                foreach (int j in columns)  
                {  
                    dr[j] = GetValueTypeForXLS(sheet.GetRow(i).GetCell(j) as XLS.HSSFCell);  
                    if (dr[j] != null && dr[j].ToString() != string.Empty)  
                    {  
                        hasValue = true;  
                    }  
                }  
                if (hasValue)  
                {  
                    dt.Rows.Add(dr);  
                }  
            }  
        }  
        return dt;  
    }  
      
    /// <summary>  
    /// 将DataTable資料導出到Excel檔案中(xls)  
    /// </summary>  
    /// <param name="dt"></param>  
    /// <param name="file"></param>  
    public static void TableToExcelForXLS(DataTable dt, string file)  
    {  
        XLS.HSSFWorkbook hssfworkbook = new XLS.HSSFWorkbook();  
        ISheet sheet = hssfworkbook.CreateSheet("Test");  
      
        //表頭  
        IRow row = sheet.CreateRow(0);  
        for (int i = 0; i < dt.Columns.Count; i++)  
        {  
            ICell cell = row.CreateCell(i);  
            cell.SetCellValue(dt.Columns[i].ColumnName);  
        }  
      
        //資料  
        for (int i = 0; i < dt.Rows.Count; i++)  
        {  
            IRow row1 = sheet.CreateRow(i + 1);  
            for (int j = 0; j < dt.Columns.Count; j++)  
            {  
                ICell cell = row1.CreateCell(j);  
                cell.SetCellValue(dt.Rows[i][j].ToString());  
            }  
        }  
      
        //轉為位元組數組  
        MemoryStream stream = new MemoryStream();  
        hssfworkbook.Write(stream);  
        var buf = stream.ToArray();  
      
        //儲存為Excel檔案  
        using (FileStream fs = new FileStream(file, FileMode.Create, FileAccess.Write))  
        {  
            fs.Write(buf, 0, buf.Length);  
            fs.Flush();  
        }  
    }  
      
    /// <summary>  
    /// 擷取單元格類型(xls)  
    /// </summary>  
    /// <param name="cell"></param>  
    /// <returns></returns>  
    private static object GetValueTypeForXLS(XLS.HSSFCell cell)  
    {  
        if (cell == null)  
            return null;  
        switch (cell.CellType)  
        {  
            case CellType.BLANK: //BLANK:  
                return null;  
            case CellType.BOOLEAN: //BOOLEAN:  
                return cell.BooleanCellValue;  
            case CellType.NUMERIC: //NUMERIC:  
                return cell.NumericCellValue;  
            case CellType.STRING: //STRING:  
                return cell.StringCellValue;  
            case CellType.ERROR: //ERROR:  
                return cell.ErrorCellValue;  
            case CellType.FORMULA: //FORMULA:  
            default:  
                return "=" + cell.CellFormula;  
        }  
    }  
    #endregion      

Excel2007：

#region Excel2007  
    /// <summary>  
    /// 将Excel檔案中的資料讀出到DataTable中(xlsx)  
    /// </summary>  
    /// <param name="file"></param>  
    /// <returns></returns>  
    public static DataTable ExcelToTableForXLSX(string file)  
    {  
        DataTable dt = new DataTable();  
        using (FileStream fs = new FileStream(file, FileMode.Open, FileAccess.Read))  
        {  
            XSSFWorkbook xssfworkbook = new XSSFWorkbook(fs);  
            ISheet sheet = xssfworkbook.GetSheetAt(0);  
      
            //表頭  
            IRow header = sheet.GetRow(sheet.FirstRowNum);  
            List<int> columns = new List<int>();  
            for (int i = 0; i < header.LastCellNum; i++)  
            {  
                object obj = GetValueTypeForXLSX(header.GetCell(i) as XSSFCell);  
                if (obj == null || obj.ToString() == string.Empty)  
                {  
                    dt.Columns.Add(new DataColumn("Columns" + i.ToString()));  
                    //continue;  
                }  
                else  
                    dt.Columns.Add(new DataColumn(obj.ToString()));  
                columns.Add(i);  
            }  
            //資料  
            for (int i = sheet.FirstRowNum + 1; i <= sheet.LastRowNum; i++)  
            {  
                DataRow dr = dt.NewRow();  
                bool hasValue = false;  
                foreach (int j in columns)  
                {  
                    dr[j] = GetValueTypeForXLSX(sheet.GetRow(i).GetCell(j) as XSSFCell);  
                    if (dr[j] != null && dr[j].ToString() != string.Empty)  
                    {  
                        hasValue = true;  
                    }  
                }  
                if (hasValue)  
                {  
                    dt.Rows.Add(dr);  
                }  
            }  
        }  
        return dt;  
    }  
      
    /// <summary>  
    /// 将DataTable資料導出到Excel檔案中(xlsx)  
    /// </summary>  
    /// <param name="dt"></param>  
    /// <param name="file"></param>  
    public static void TableToExcelForXLSX(DataTable dt, string file)  
    {  
        XSSFWorkbook xssfworkbook = new XSSFWorkbook();  
        ISheet sheet = xssfworkbook.CreateSheet("Test");  
      
        //表頭  
        IRow row = sheet.CreateRow(0);  
        for (int i = 0; i < dt.Columns.Count; i++)  
        {  
            ICell cell = row.CreateCell(i);  
            cell.SetCellValue(dt.Columns[i].ColumnName);  
        }  
      
        //資料  
        for (int i = 0; i < dt.Rows.Count; i++)  
        {  
            IRow row1 = sheet.CreateRow(i + 1);  
            for (int j = 0; j < dt.Columns.Count; j++)  
            {  
                ICell cell = row1.CreateCell(j);  
                cell.SetCellValue(dt.Rows[i][j].ToString());  
            }  
        }  
      
        //轉為位元組數組  
        MemoryStream stream = new MemoryStream();  
        xssfworkbook.Write(stream);  
        var buf = stream.ToArray();  
      
        //儲存為Excel檔案  
        using (FileStream fs = new FileStream(file, FileMode.Create, FileAccess.Write))  
        {  
            fs.Write(buf, 0, buf.Length);  
            fs.Flush();  
        }  
    }  
      
    /// <summary>  
    /// 擷取單元格類型(xlsx)  
    /// </summary>  
    /// <param name="cell"></param>  
    /// <returns></returns>  
    private static object GetValueTypeForXLSX(XSSFCell cell)  
    {  
        if (cell == null)  
            return null;  
        switch (cell.CellType)  
        {  
            case CellType.BLANK: //BLANK:  
                return null;  
            case CellType.BOOLEAN: //BOOLEAN:  
                return cell.BooleanCellValue;  
            case CellType.NUMERIC: //NUMERIC:  
                return cell.NumericCellValue;  
            case CellType.STRING: //STRING:  
                return cell.StringCellValue;  
            case CellType.ERROR: //ERROR:  
                return cell.ErrorCellValue;  
            case CellType.FORMULA: //FORMULA:  
            default:  
                return "=" + cell.CellFormula;  
        }  
    }      

注意：操作Excel2003與操作Excel2007使用的是不同的命名空間下的内容

使用NPOI.HSSF.UserModel空間下的HSSFWorkbook操作Excel2003

使用NPOI.XSSF.UserModel空間下的XSSFWorkbook操作Excel2007

/// <summary>
        /// 寫入到檔案  IWorkbook 接口實作
        /// </summary>
        /// <param name="book"></param>
        /// <param name="fileName"></param>
        /// <returns></returns>
        private bool WriteToFile(IWorkbook book, string fileName)
        {
            bool result = true;
            try
            {
                using (MemoryStream ms = new MemoryStream())
                {
                    string filePath = Path.GetDirectoryName(fileName);
                    if (!Directory.Exists(filePath))
                    {
                        Directory.CreateDirectory(filePath);
                    }
                    book.Write(ms);
                    //儲存為Excel檔案  
                    var buf = ms.ToArray();
                    using (FileStream fs = new FileStream(fileName, FileMode.Create, FileAccess.Write))
                    {
                        fs.Write(buf, 0, buf.Length);
                        fs.Flush();
                    }
                }
            }
            catch (Exception e)
            {
                LogHelper.WriteErrorLog(e.Message, e);
                result = false;
            }
            finally
            {
                GC.Collect();
            }
            return result;
        }