//图片验证 根据文件流判断文件是否时图片：
public static boolean isImage(MultipartFile multfile) {
String suffix = ImgUtil.getImgSuffix(multfile.getOriginalFilename());
boolean isImage;
String uuid = UUID.randomUUID().toString().replace("-", "").toLowerCase();
final File excelFile;
try {
excelFile = File.createTempFile(uuid, suffix);
multfile.transferTo(excelFile);
Image image = ImageIO.read(excelFile);
isImage = image != null;
excelFile.delete();
} catch (IOException e) {
logger.error("图片上传时，验证出错",e);
isImage = false;
}
return isImage;
}