/**

     * 使用session - 传统方式

     */

    @RequestMapping("/hello13.action")

    public String hello13(HttpSession session){

        session.setAttribute("prod", "电视机");

        return "hello";

    }

    @RequestMapping("/hello14.action")

    public String hello14(HttpSession session){

        String prod = (String) session.getAttribute("prod");

        System.out.println(prod);

        return "hello";

    }

    /**

     * 使用session - 注解方式

     * @throws Exception

     */

    @RequestMapping("/hello15.action")

    public String hello15(Model model){

        model.addAttribute("prod","洗衣机");

        return "hello";

    }

    @RequestMapping("/hello16.action")

    public String hello16(HttpSession session){

        String prod = (String) session.getAttribute("prod");

        System.out.println(prod);

        return "hello";

    }