Thymeleaf - ${…}

@GetMapping("/upload/{id}")
public String uploadFile(@PathVariable("id") String id, ModelMap modelMap, HttpServletRequest request, HttpSession session)
{
    //两种获取HttpSession方式相同
    request.getSession().setAttribute("aa","556");
    session.setAttribute("bb","996");
    
    modelMap.addAttribute("id",id);
    return prefix + "/upload";
}

注意：session中的属性获取需要session.*方式获取