NPOI導入導出Excel（.Net framework，.Net Core面向對象操作，轉換一下即可）

直接上代碼吧，工具類，爲了以後要使用可以直接拷貝過去使用方便~

public class ExcelService
    {
        public static DataTable ReadExcelToDataTable(string filePath, string sheetName)
        {
            var data = new DataTable();

            if (string.IsNullOrWhiteSpace(filePath)) throw new Exception("要讀取的文件路徑不能爲空！");

            //讀取文件
            IWorkbook workbook = null;
            using (var fs = new FileStream(filePath, FileMode.Open, FileAccess.Read))
            {
                string a = ".xlsx";
                string b = ".xls";
                string exName = Path.GetExtension(filePath);
                if (exName.IndexOf(a) > 0) workbook = new XSSFWorkbook(fs);
                if (exName.IndexOf(b) > 0) workbook = new HSSFWorkbook(fs);
            }
            if (workbook == null) throw new Exception("文件不合法！");

            //讀取Sheet
            ISheet sheet = null;
            if (!string.IsNullOrWhiteSpace(sheetName)) sheet = workbook.GetSheet(sheetName);
            if (sheet == null) sheet = workbook.GetSheetAt(0);
            if (sheet == null) throw new Exception("未讀取到任何Sheet信息！");

            IRow firstRow = sheet.GetRow(0);//讀取第一行
            int cellCount = firstRow.LastCellNum;//拿到第一行的列的數量

            //第一行是列信息，初始化表格列
            for (int i = firstRow.FirstCellNum; i < cellCount; i++)
            {
                ICell cell = firstRow.GetCell(i);
                if (cell == null) throw new Exception(string.Format("未讀取到第{0}列列名！", i));
                string cellValue = cell.StringCellValue;
                if (!string.IsNullOrWhiteSpace(cellValue))
                {
                    DataColumn column = new DataColumn(cellValue);
                    data.Columns.Add(column);
                }
            }

            int startRow = sheet.FirstRowNum + 1;//行開始索引
            int rowCount = sheet.LastRowNum + 1;//總行數，因爲第一行是列信息，所以需要+1

            for (int i = startRow; i < rowCount; i++)
            {
                IRow row = sheet.GetRow(i);
                if (row == null) continue;

                DataRow dataRow = data.NewRow();
                for (int j = row.FirstCellNum; j < cellCount; ++j)
                {
                    var cell = row.GetCell(j);
                    if (cell != null) dataRow[j] = cell.ToString();
                }
                data.Rows.Add(dataRow);
            }
            return data;
        }

        public static void Export(string filePath, params Tuple<string, DataTable>[] dataList)
        {
            if (string.IsNullOrWhiteSpace(filePath)) throw new Exception("導出路徑不能爲空！");
            if (dataList == null || dataList.Length <= 0) throw new Exception("沒有需要導出的數據！");

            var workbook = new XSSFWorkbook();

            int index = 0;
            foreach (var dataItem in dataList)
            {
                string sheetName = dataItem.Item1;
                var data = dataItem.Item2;
                index++;

                if (string.IsNullOrWhiteSpace(sheetName)) sheetName = "Sheet" + index;
                var sheet = workbook.CreateSheet(sheetName);

                IRow row;
                ICell cell;

                int startRowIndex = 0;

                //列頭
                row = sheet.CreateRow(startRowIndex++);
                for (int i = 0; i < data.Columns.Count; i++)
                {
                    cell = row.CreateCell(i);
                    string columnName = data.Columns[i].ColumnName;
                    cell.SetCellValue(columnName);
                }

                //數據
                for (int i = 0; i < data.Rows.Count; i++)
                {
                    int rowIndexItem = i + startRowIndex;
                    row = sheet.CreateRow(rowIndexItem);

                    var rowData = data.Rows[i];
                    for (int j = 0; j < data.Columns.Count; j++)
                    {
                        cell = row.CreateCell(j);
                        string columnValue = rowData[j].ToString();
                        cell.SetCellValue(columnValue);
                    }
                }

                //自動列寬
                for (int i = 0; i < data.Rows.Count + 1; i++)
                {
                    sheet.AutoSizeColumn(i);
                }
            }

            using (FileStream fs = new FileStream(filePath, FileMode.Create))
            {
                workbook.Write(fs);
            }
        }
    }

 

Ending~