CommonsMultipartFile shopImg = null;
CommonsMultipartResolver commonsMultipartResolver = new CommonsMultipartResolver(request.getSession().getServletContext());
if(commonsMultipartResolver.isMultipart(request)){
   MultipartHttpServletRequest multipartHttpServletRequest = (MultipartHttpServletRequest)request;
   shopImg = (CommonsMultipartFile) multipartHttpServletRequest.getFile("shopImg");
}else{
   modelMap.put("success",false);
   modelMap.put("errMsg","上传图片不能为空");
   return modelMap;
}

老师，我没有上传图片，但打断点调试的时候isMultipart(request)的结果返回了true，怎么回事呢？