NPOI

通过Nuget安装NPOI类库

  public class ExcelOperator
    {
        /// <summary>
        /// Init Workbook
        /// </summary>
        /// <param name="path">excel file path</param>
        /// <returns></returns>
        private IWorkbook InitializeWorkbook(string path)
        {
            string extension = Path.GetExtension(path);
            if (string.IsNullOrEmpty(extension) ||
                (
                 !".xlsx".Equals(extension.ToLower()) &&
                 !".xls".Equals(extension.ToLower())
                )
               )
            {
                throw new InvalidOperationException("this is not a excel file");
            }

            IWorkbook workbook;

            if (".xlsx".Equals(extension.ToLower()))
            {
                workbook = new XSSFWorkbook();
            }
            else
            {
                workbook = new HSSFWorkbook();
            }

            return workbook;
        }

        /// <summary>
        /// Init Workbook
        /// </summary>
        /// <param name="path">excel file path</param>
        /// <param name="fileStream"></param>
        /// <returns></returns>
        private IWorkbook InitializeWorkbook(string path, out FileStream fileStream)
        {
            string extension = Path.GetExtension(path);
            if (string.IsNullOrEmpty(extension) ||
                (
                 !".xlsx".Equals(extension.ToLower()) &&
                 !".xls".Equals(extension.ToLower())
                )
               )
            {
                throw new InvalidOperationException("this is not a excel file");
            }

            IWorkbook workbook;
            fileStream = new FileStream(path, FileMode.OpenOrCreate, FileAccess.ReadWrite);

            if (".xlsx".Equals(extension.ToLower()))
            {
                workbook = new XSSFWorkbook(fileStream);
            }
            else
            {
                workbook = new HSSFWorkbook(fileStream);
            }

            return workbook;
        }

        /// <summary>
        /// 将excel中的数据导入到DataTable中
        /// </summary>
        /// <param name="path">excel路径</param>
        /// <param name="sheetName">excel工作薄sheet的名称</param>
        /// <param name="isFirstRowColumn">第一行是否是DataTable的列名</param>
        /// <returns>返回的DataTable</returns>
        public DataTable ExcelToDataTable(string path, string sheetName, bool isFirstRowColumn)
        {
            FileStream fileStream = null;

            try
            {
                DataTable data = new DataTable();

                IWorkbook workbook = InitializeWorkbook(path, out fileStream);

                //如果不指定sheet,则获取第一个sheet
                ISheet sheet = sheetName != null ? workbook.GetSheet(sheetName) : workbook.GetSheetAt(0);

                //check sheet是否存在
                if (sheet == null)
                {
                    throw new InvalidOperationException("Sheet does not exist");
                }

                IRow firstRow = sheet.GetRow(0);
                int firstCellNum = firstRow.FirstCellNum;
                int lastCellNum = firstRow.LastCellNum;

                int startRow = 0;
                if (isFirstRowColumn)
                {
                    //添加列
                    for (int i = firstCellNum; i < lastCellNum; i++)
                    {
                        ICell cell = firstRow.GetCell(i);
                        if (cell != null)
                        {
                            string cellValue = cell.StringCellValue;
                            if (cellValue != null)
                            {
                                var column = new DataColumn(cellValue);
                                data.Columns.Add(column);
                            }
                        }
                    }
                    startRow = sheet.FirstRowNum + 1;
                }
                else
                {
                    startRow = sheet.FirstRowNum;
                }

                //最后一列的标号
                int rowCount = sheet.LastRowNum;
                for (int i = startRow; i <= rowCount; i++)
                {
                    IRow row = sheet.GetRow(i);
                    if (row == null) continue;

                    DataRow dataRow = data.NewRow();
                    for (int j = firstCellNum; j < lastCellNum; j++)
                    {
                        if (row.GetCell(j) != null)
                            dataRow[j] = row.GetCell(j).ToString();
                    }
                    data.Rows.Add(dataRow);
                }

                return data;
            }
            catch (Exception)
            {
                throw;
            }
            finally
            {
                if (fileStream != null) fileStream.Close();
            }
        }

        /// <summary>
        /// 将DataTable数据导入到excel中
        /// </summary>
        /// <param name="data">要导入的数据</param>
        /// <param name="sheetName">要导入的excel的sheet的名称</param>
        /// <param name="isColumnWritten">DataTable的列名是否要导入</param>
        /// <param name="path">要导入数据的excel路径</param>
        /// <returns>导入数据行数(包含列名那一行)</returns>
        public int DataTableToExcel(DataTable data, string sheetName, bool isColumnWritten, string path)
        {
            int count;

            IWorkbook workbook = InitializeWorkbook(path);

            if (string.IsNullOrEmpty(sheetName))
            {
                sheetName = "Sheet1";
            }

            ISheet sheet = workbook.CreateSheet(sheetName);
            //写入DataTable的列名
            if (isColumnWritten)
            {
                IRow row = sheet.CreateRow(0);
                for (int j = 0; j < data.Columns.Count; ++j)
                {
                    row.CreateCell(j).SetCellValue(data.Columns[j].ColumnName);
                }
                count = 1;
            }
            else
            {
                count = 0;
            }

            //写入行数据
            for (int i = 0; i < data.Rows.Count; ++i)
            {
                IRow row = sheet.CreateRow(count);
                for (int j = 0; j < data.Columns.Count; ++j)
                {
                    row.CreateCell(j).SetCellValue(data.Rows[i][j].ToString());
                }
                count++;
            }

            using (var fileStream = new FileStream(path, FileMode.OpenOrCreate, FileAccess.Write))
            {
                workbook.Write(fileStream);
            }

            return count;
        }

    }