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

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

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

@Controller
@Scope("session")

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

@Autowired
   private User user

<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>

@Autowired
private User user

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

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

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

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

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

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

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

@Controller
@SessionAttributes("personObj")
public class PersonController {

    @RequestMapping(value="/person-form")
    public ModelAndView personPage() {
        return new ModelAndView("person-page", "person-entity", new Person());
    }

    @RequestMapping(value="/process-person")
    public ModelAndView processPerson(@ModelAttribute Person person) {
        ModelAndView modelAndView = new ModelAndView();
        modelAndView.setViewName("person-result-page");

        modelAndView.addObject("pers", person);
        modelAndView.addObject("personObj", person);

        return modelAndView;
    }

}

@RequestMapping("/testing")
@Controller
public class TestController {
@RequestMapping(method = RequestMethod.GET)
public String testMestod(HttpServletRequest request){
    request.getSession().setAttribute("name", "value");
    return "testJsp";
  }
}

@RequestMapping(value = "/login")
        @ResponseBody
        public BooleanResponse login(HttpSession session,HttpServletRequest request){
            //HttpServletRequest used to take data to the controller
            String username = request.getParameter("username");
            String password = request.getParameter("password");

           //Here you set your values to the session
           session.setAttribute("username", username);
           session.setAttribute("email", email);

          //your code goes here
}

<c:out value="${username}"></c:out>
<c:out value="${email}"></c:out>

@GetMapping
public String hello(HttpSession session) {
    session.setAttribute("name","value");
    return "hello";
}

hi dear try this...
@Controller
@RequestMapping("/owners/{ownerId}/pets/{petId}/edit")
@SessionAttributes("pet")
public class EditPetForm {

    @ModelAttribute("types")

    public Collection<PetType> populatePetTypes() {
        return this.clinic.getPetTypes();
    }

    @RequestMapping(method = RequestMethod.POST)
    public String processSubmit(@ModelAttribute("pet") Pet pet,
            BindingResult result, SessionStatus status) {
        new PetValidator().validate(pet, result);
        if (result.hasErrors()) {
            return "petForm";
        }else {
            this.clinic.storePet(pet);
            status.setComplete();
            return "redirect:owner.do?ownerId="
                + pet.getOwner().getId();
        }
    }
}

HttpServletRequest request = (HttpServletRequest) context.getExternalContext().getNativeRequest();

                                                            request.getSession().setAttribute("errorMsg", "your massage");

<c:remove var="errorMsg" scope="session"/>