springboot上传文件并检查图片大小与格式

@PostMapping(value = "/uploadDriverImage")
    public JsonResVo uploadDriverImage(@RequestParam("file") MultipartFile file) {
        try {
            //检查文件是否为空
            if(file.isEmpty()) {
                return JsonResVo.buildErrorResult(ErrorEnum.ERROR_DEFAULT.getErrorCode(), "请选择图片");
            }
            //检查文件大小
            if(file.getSize() > Constant.M2_TO_BYTE) {
                return JsonResVo.buildErrorResult(ErrorEnum.ERROR_DEFAULT.getErrorCode(), "请上传2M以内的图片");    
            }
            //检查是否是图片
            BufferedImage bi = ImageIO.read(file.getInputStream());
            if(bi == null){ 
                return JsonResVo.buildErrorResult(ErrorEnum.ERROR_DEFAULT.getErrorCode(), "上传的文件不是图片");    
            }
            
            String originalFilename = file.getOriginalFilename();
            String fileType = null;
            if(originalFilename.contains(".")) {
                fileType = originalFilename.substring(originalFilename.lastIndexOf(".")+1);
            } else {
                fileType = Constant.IMAGE_TYPE_JPG;
            }
            String ossFilePath = OSSUtil.upload(file.getInputStream(), System.currentTimeMillis()+"", fileType, "driverimage");
            return JsonResVo.buildSuccess(ossFilePath);
        } catch (Exception e) {
            e.printStackTrace();
            return JsonResVo.buildErrorResult(ErrorEnum.ERROR_DEFAULT.getErrorCode(), e.getMessage());
        }
    }