@RequestMapping(value = "/loginUser", produces = {"text/html;charset=utf-8"}, method = RequestMethod.POST)
public String login(@RequestParam(value = "user", required = false) String user,
                        @RequestParam(value = "password") String password,
                        @RequestParam(value = "telephone") String telephone,
                        HttpSession session) {
   。。。。。。省略一大段代码
   //这里设置一下session，保存登录的用户信息到session中去
                session.setAttribute("user",userDO);
}

获取session。
 /**
     * 登录的时候进到主页面
     * @return
     */
    @RequestMapping("/")
    public ModelAndView requestMapping(HttpSession session) {
        ModelAndView map = new ModelAndView("index");
        System.out.println(session.getAttribute("user"));
        userMapper userMapper = (userMapper)session.getAttribute("user");
        if(userMapper!=null)
        map.addObject("userid", userMapper.getUserid());
        return map;
    }