How to use Session attributes in Spring-mvc

Question

Could you help me write spring mvc style analog of this code?

 session.setAttribute("name","value");

And how to add an element that is annotated by @ModelAttribute annotation to session and then get access to it?

Answer 1

If you want to delete object after each response you don't need session,

If you want keep object during user session , There are some ways:

1. directly add one attribute to session:

   @RequestMapping(method = RequestMethod.GET)
   public String testMestod(HttpServletRequest request){
      ShoppingCart cart = (ShoppingCart)request.getSession().setAttribute("cart",value);
      return "testJsp";
   }
   

   and you can get it from controller like this :

   ShoppingCart cart = (ShoppingCart)session.getAttribute("cart");
   

2. Make your controller session scoped

   @Controller
   @Scope("session")
   

3. Scope the Objects ,for example you have user object that should be in session every time:

   @Component
   @Scope("session")
   public class User
    {
       String user;
       /*  setter getter*/
     }
   

   then inject class in each controller that you want

      @Autowired
      private User user
   

   that keeps class on session.

4. The AOP proxy injection : in spring -xml:

   <beans xmlns="http://www.springframework.org/schema/beans"
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xmlns:aop="http://www.springframework.org/schema/aop"
     xsi:schemaLocation="http://www.springframework.org/schema/beans
       http://www.springframework.org/schema/beans/spring-beans-3.1.xsd
       http://www.springframework.org/schema/aop
       http://www.springframework.org/schema/aop/spring-aop-3.1.xsd">
   
     <bean id="user"    class="com.User" scope="session">     
         <aop:scoped-proxy/>
     </bean>
   </beans>
   

   then inject class in each controller that you want

   @Autowired
   private User user
   

5.Pass HttpSession to method:

 String index(HttpSession session) {
            session.setAttribute("mySessionAttribute", "someValue");
            return "index";
        }

6.Make ModelAttribute in session By @SessionAttributes("ShoppingCart"):

  public String index (@ModelAttribute("ShoppingCart") ShoppingCart shoppingCart, SessionStatus sessionStatus) {
//Spring V4
//you can modify session status  by sessionStatus.setComplete();
}

or you can add Model To entire Controller Class like,

@Controller
    @SessionAttributes("ShoppingCart")
    @RequestMapping("/req")
    public class MYController {

        @ModelAttribute("ShoppingCart")
        public Visitor getShopCart (....) {
            return new ShoppingCart(....); //get From DB Or Session
        }  
      }

each one has advantage and disadvantage:

@session may use more memory in cloud systems it copies session to all nodes, and direct method (1 and 5) has messy approach, it is not good to unit test.

To access session jsp

<%=session.getAttribute("ShoppingCart.prop")%>

in Jstl :

<c:out value="${sessionScope.ShoppingCart.prop}"/>

in Thymeleaf:

<p th:text="${session.ShoppingCart.prop}" th:unless="${session == null}"> . </p>