限制上传图片大小，格式为jpg 或者 png

在Constants.java中：
public static HashMap<String, String> getPhotoTypeMap() {
HashMap<String, String> resultMap = new HashMap<String, String>();
resultMap.put("jpg", "");
resultMap.put("png", "");
return resultMap;
}
@RequestMapping(value = "/uploadAvatarImage", method = RequestMethod.POST)
public String uploadAvatarImage(Model uiModel, @RequestParam("avatarImageFile") MultipartFile file) {
String originalFileName=file.getOriginalFilename();
if (!"".equals(file.getOriginalFilename()) && file.getSize() <= Constants.SYSTEM_IMAGE_MAX_SIZE) {
String type=originalFileName.substring(originalFileName.lastIndexOf(".")+1);
if (!Constants.getPhotoTypeMap().containsKey(type.toLowerCase())) {
uiModel.addAttribute("validateMessage", "The format of the image is not supported, you can only upload the format of jpg or png.");
return showProfile(uiModel,"Y");
}
}

if (file == null || file.getSize() <= 0) {
uiModel.addAttribute("validateMessage", "The image size can not be zero.");
return showProfile(uiModel,"Y");
}

if (file.getSize() > Constants.SYSTEM_IMAGE_MAX_SIZE) {
uiModel.addAttribute("validateMessage", "The image size can not exceed 1024K.");
return showProfile(uiModel,"Y");
}

try {
UploadFile uploadThumbnailImage = Tools.uploadImageWithThumbnail(file, Constants.UPLOADFILE_HOMEOWNER_AVATAR_PATH, Constants.SYSTEM_THUMBNAIL_IMAGE_WIDTH, Constants.SYSTEM_THUMBNAIL_IMAGE_HEIGHT);

if (uploadThumbnailImage != null) {
User currentUser = getCurrentUser();

uploadThumbnailImage.setUser(currentUser);
uploadThumbnailImage.setCategory(Constants.UPLOADFILE_AVATAR_TYPE);

uploadFileService.saveUploadImage(uploadThumbnailImage);
}

} catch (IOException e) {
e.printStackTrace();
}

showProfile(uiModel,"N");

return "redirect:/homeowner/profile";
}