poi导入Execl数据

 @GetMapping("/excel/upload")
    public void importExcel(@RequestParam("excelFile") MultipartFile multipartFile) throws IOException {


        if (multipartFile==null|| multipartFile.getSize()==0){
            log.error("文件上传错误，重新上传");
        }
        String filename = multipartFile.getOriginalFilename();
        if (!(filename.endsWith(".xls")|| filename.endsWith(".xlsx"))){
            log.error("文件上传格式错误，请重新上传");
        }
        List<RuleVo> ruleVoList = readXLS(multipartFile);
        System.out.println("完毕");


    }

    public List<RuleVo> readXLS(MultipartFile file) throws IOException {
        List<RuleVo> ruleVoList =new ArrayList<>();

        InputStream inputStream = file.getInputStream();
        HSSFWorkbook workbook = new HSSFWorkbook(inputStream);

        //读取第一张sheet
        HSSFSheet sheet = workbook.getSheetAt(0);
        String errorMsg="";
        //遍历每一行Excel获取内容
        for (int rowNum = 1; rowNum <= sheet.getLastRowNum(); rowNum++) {
            HSSFRow row = sheet.getRow(rowNum);
            if (row!=null){
                RuleVo ruleVo = new RuleVo();
                //使用了getStringCellValue()方法来获取值，POI会判断单元格的类型，如果非字符串类型就会抛出上面的异常。
                //所以先使用setCellType()方法先将该单元格的类型设置为STRING
                //然后poi会根据字符串读取它
                row.getCell(0).setCellType(CellType.STRING);
                HSSFCell cell = row.getCell(1);
                //todo  有指针异常风险 row.getCell记得判断。
                row.getCell(1).setCellType(CellType.STRING);
                row.getCell(2).setCellType(CellType.STRING);
                row.getCell(3).setCellType(CellType.STRING);
                row.getCell(5).setCellType(CellType.STRING);
                row.getCell(6).setCellType(CellType.STRING);
                ruleVo.setName(row.getCell(0).getStringCellValue());
                ruleVo.setGroupId(Long.parseLong(row.getCell(1).getStringCellValue()));
                ruleVo.setChannel(row.getCell(2).getStringCellValue());
                ruleVo.setVersion(Integer.parseInt(row.getCell(3).getStringCellValue()));
                String ruleContentList = row.getCell(5).getStringCellValue();
                RuleContent[] array = new Gson().fromJson(ruleContentList,RuleContent[].class);
                List<RuleContent> list = Arrays.asList(array);
                ruleVo.setContentList(list);
                ruleVo.setOperator(row.getCell(6).getStringCellValue());
                ruleVo.setCreateTime(row.getCell(7).getDateCellValue());
                ruleVo.setUpdateTime(row.getCell(8).getDateCellValue());
                ruleVoList.add(ruleVo);
            }
        }
        return ruleVoList;
    }