读取ecxel中数据

//在nuget中导入npoi.excel管理器



        /// </summary>
        /// 读取excel,放入datatable中
        /// <param name="filename">文件路劲</param>
        /// <param name="sheetname">表名</param>
        /// <param name="isfirstrowcolumn">是否有表头</param>
        /// <returns></returns>
public static datatable readexceltodatatable(string filename, string sheetname = null, bool isfirstrowcolumn = false)
        {
            //定义要返回的datatable对象
            datatable data = new datatable();
            npoi.ss.usermodel.isheet sheet = null;
            //数据开始行(排除标题行)
            int startrow = 0;

            if (!file.exists(filename))
            {
                return null;
            }
            //根据指定路径读取文件
            filestream fs = new filestream(filename, filemode.open, fileaccess.read);
            npoi.ss.usermodel.iworkbook workbook = npoi.ss.usermodel.workbookfactory.create(fs);
            //iworkbook workbook = new hssfworkbook(fs);
            //如果有指定工作表名称
            if (!string.isnullorempty(sheetname))
            {
                sheet = workbook.getsheet(sheetname);
                //如果没有找到指定的sheetname对应的sheet，则尝试获取第一个sheet
                if (sheet == null)
                {
                    sheet = workbook.getsheetat(0);
                }
            }
            else
            {
                //如果没有指定的sheetname，则尝试获取第一个sheet
                sheet = workbook.getsheetat(0);
            }
            if (sheet != null)
            {
                npoi.ss.usermodel.irow firstrow = sheet.getrow(0);
                //一行最后一个cell的编号 即总的列数
                int cellcount = firstrow.lastcellnum;
                //如果第一行是标题列名

                for (int i = firstrow.firstcellnum; i < cellcount; ++i)
                {
                    npoi.ss.usermodel.icell cell = firstrow.getcell(i);
                    if (cell != null)             //遍历excel表
                    {

                        //     string cellvalue = cell.stringcellvalue;
                        if (cell != null)
                        {
                            datacolumn column = new datacolumn(cell.tostring());
                            data.columns.add(column);
                        }
                    }
                }
                if (isfirstrowcolumn)
                {
                    startrow = sheet.firstrownum + 1;      //有表头时不读取表头
                }
                else
                {
                    startrow = sheet.firstrownum;
                }
                //最后一列的标号
                int rowcount = sheet.lastrownum;
                for (int i = startrow; i <= rowcount; ++i)
                {
                    npoi.ss.usermodel.irow row = sheet.getrow(i);
                    if (row == null) continue; //没有数据的行默认是null　　　　　　　

                    datarow datarow = data.newrow();
                    for (int j = row.firstcellnum; j < cellcount; ++j)
                    {
                        if (row.getcell(j) != null) //同理，没有数据的单元格都默认是null
                            datarow[j] = row.getcell(j).tostring();
                    }
                    data.rows.add(datarow);
                }
            }
            return data;

        }