Change JForum Locale in real time

[Migrated From Jforum.net]

Hi, i have integrated JForum in my webapp, I create and edit users out of JForum, and all found ok, but i want know how i can change Locale value in real time, to user do click in JForum link and JForum appear in the previus select language. Now i change lenguage value in DB, and if user change it, and restart web browser (restart session web browser) JForum appear in new language. but i want can change the Locale value IN SAME SESSION.

Somebody can help me?, thanks!
[originally posted on jforum.net by MiLLeN]

[Migrated From Jforum.net]

I see this post https://coderanch.com/t/578473

THen, i add to SessionFacade my personal method:

public static void setUserLang(Locale lang){
    getUserSession().setLang(lang.getLanguage());
}

And i try to get my set Language in my webapp Spring context in services method of JForum class.

...
context.put("logged", SessionFacade.isLogged());

/* MY CODE */

// Actualiza lenguaje del usuario.
if (SessionFacade.getUserSession() != null) {
    Locale lang = RequestContextUtils.getLocaleResolver(req).resolveLocale(req);
    SessionFacade.setUserLang(lang);
}

/* END MY CODE */

// Process security data
SecurityRepository.load(SessionFacade.getUserSession().getUserId());
...

But say me one NullPointerException error, Why?, How i can fix?. is why my webapp Spring context is not possible to access from JForum?, if is possible... how?

Thanks!
[originally posted on jforum.net by MiLLeN]