如何导入一个excel

public List<String[]> importExcel(File file) throws IOException {
        FileInputStream fileInputStream = new FileInputStream(file);
        //创建核心对象
        XSSFWorkbook xw = new XSSFWorkbook(fileInputStream);
        //获取sheet表
        XSSFSheet sheet = xw.getSheetAt(0);
        //获取sheet表中对应总共有多少行
        int lastRowNum = sheet.getLastRowNum();
        List<String[]> listDatas = new ArrayList<String[]>();
        for (int i = 1; i <= lastRowNum; i++) {
            //获取指定的行
            XSSFRow row = sheet.getRow(i);
            //获取行对应总共有多少个单元格
            short lastCellNum = row.getLastCellNum();
            String[] datas = new String[lastCellNum];
            for (int j = 0; j < lastCellNum; j++) {
                //获取指定的单元格
                XSSFCell cell = row.getCell(j);
                //获取单元格对应指定的值
                datas[j] = cell.getStringCellValue();
            }
            listDatas.add(datas);
        }
        return listDatas;



    }