java – 对多部分文件进行空检查

我正在Spring控制器中处理两个不同的多部分文件.

然后将这两个文件发送到服务以设置实体.但是如果两个或一个为null,则抛出NullPointerException.如何检查两个文件中的任何一个(projectImg / chartImg)是否为空？

到目前为止,这是我的代码：

public void uploadImages(MultipartFile projectImg,MultipartFile chartImg,Long projectId) throws ValidationException,IOException {
    Project project = projectRepository.findOne(projectId);
    Project save = projectRepository.save(project);

    int maximumSizeMB = 15000000;

    if (!projectImg.isEmpty()) {
        if (projectImg.getSize() > maximumSizeMB) {
            throw new ValidationException("Image size is too big. Maximum size is 15 MB");
        }

        byte[] projectFile = ImageCompression.compressImage(projectImg);
        project.setProjectImg(projectFile);
        save.getProjectImg();
    }
    if (!chartImg.isEmpty()) {
        if (chartImg.getSize() > maximumSizeMB) {
            throw new ValidationException("Image size is too big. Maximum size is 15 MB");
        }

        byte[] chartFile = ImageCompression.compressImage(chartImg);
        project.setChartImg(chartFile);
        save.getChartImg();
    }
    projectRepository.save(project);
}

谢谢！