Passing model attribute during redirect in spring MVC and avoiding the same in URL

Question

My objective is to pass model attributes from controller to JSP page during a redirect and avoid the attribute being displayed in URL. The source code below is validating login from datastore using java data objects.

Controller:

@Controller public class LoginController {     int count;     PersistenceManager pm = PMF.get().getPersistenceManager();      //Instance of data class         User user;     ModelAndView modelAndView=new ModelAndView();      @RequestMapping(value="/Login",method = RequestMethod.POST)     public ModelAndView loginValidate(HttpServletRequest req){          //Getting login values         String uname=req.getParameter("nameLogin");         String pswd1=req.getParameter("pswdLogin");         count=0;           user=new User();          //Generating Query         Query q = pm.newQuery(User.class);         q.setFilter("userName == userNameParam");         q.declareParameters("String userNameParam");          try{             List<User> results = (List<User>) q.execute(uname);               for (User u: results) {                  String userName=u.getUserName();                  if(userName.equals(uname)){                      System.out.println(u.getPassword());                      if(u.getPassword().equals(pswd1)){                         count=count+1;                         modelAndView.setViewName("redirect:welcome");                         modelAndView.addObject("USERNAME",uname);                         return modelAndView;                      }          //rest of the logic      } 

JSP:

 <h1>Welcome ${USERNAME} </h1> 

My current URL is /welcome?USERNAME=robin
My goal is to display it as /welcome
Also, my page is supposed to display "Welcome robin" whereas it displays only Welcome.

Answer 1

RedirectAttributes only work with RedirectView, please follow the same

@RequestMapping(value="/Login",method = RequestMethod.POST) public RedirectView loginValidate(HttpServletRequest req, RedirectAttributes redir){ ...      redirectView= new RedirectView("/foo",true);     redir.addFlashAttribute("USERNAME",uname);     return redirectView; } 

Those flash attributes are passed via the session (and are destroyed immediately after being used - see Spring Reference Manual for details). This has two interests :

• they are not visible in URL
• you are not restricted to String, but may pass arbitrary objects.