public Map act(Redirector redirector,
    SourceResolver resolver,
    Map objectModel,
    String source,
    Parameters par) throws Exception 
{
        String lang;
        if (objectModel.containsKey(PARAM_LANG)) {
            lang = (String)(objectModel.get(PARAM_LANG));
        } else {
            lang = getLang(objectModel, par);
            objectModel.put(PARAM_LANG, lang);
        }
        // Creating session to store the language code
        Request request = ObjectModelHelper.getRequest(objectModel);
        request.getSession(createSession);
        if (storeInSession || storeInCookie) {
                storeLang(objectModel, lang);
        }
        Map m = new HashMap(1);
        m.put(PARAM_LANG, lang);
        return m;
}

Selects language if it is not set already in objectModel Puts lang parameter to session and to objectModel if it is not already there.

 public  void configure(Configuration conf) throws ConfigurationException 
{
            
        getLogger().warn("LangSelect action is deprecated. Please use LocaleAction");
        if (conf != null) {
            Configuration child = conf.getChild("store-in-request");
            this.storeInRequest = child.getValueAsBoolean(false);
            child = conf.getChild("create-session");
            this.createSession = child.getValueAsBoolean(false);
            child = conf.getChild("store-in-session");
            this.storeInSession = child.getValueAsBoolean(false);
            child = conf.getChild("store-in-cookie");
            this.storeInCookie = child.getValueAsBoolean(false);
        }
}

Configure this action.

 public static String getLang(Map objectModel,
    Parameters par) 
{
        List langs_avail = new ArrayList();
        List langs_user = new ArrayList();
        Iterator params = par.getParameterNames();
        while (params.hasNext()) {
            String paramname = (String)(params.next());
            if (paramname.startsWith("available_lang")) {
                langs_avail.add(par.getParameter(paramname, null));
            }
        }
        String def_lang = par.getParameter("default_lang", LangSelect.DEFAULT_LANG);
        Request request = ObjectModelHelper.getRequest(objectModel);
        String lang = null;
        lang = request.getParameter(PARAM_LANG);
        if (lang == null) {
            Session session = request.getSession(false);
            if (session != null) {
                Object session_lang = session.getAttribute(PARAM_LANG);
                if (session_lang != null) {
                    lang = session_lang.toString();
                }
            }
        }
        if (lang == null) {
            Cookie[] cookies = request.getCookies();
            if (cookies != null) {
                for ( int i = 0; i <  cookies.length; i++) {
                    Cookie cookie = cookies[i];
                    if (cookie.getName().equals(PARAM_LANG)) {
                        lang = cookie.getValue();
                    }
                }
            }
        }
        if (lang == null) {
            Enumeration locales = request.getLocales();
            while (locales.hasMoreElements()) {
                Locale locale = (Locale)(locales.nextElement());
                langs_user.add(locale.getLanguage());
            }
            boolean match = false;
            int i = 0;
            for ( ; i <  langs_user.size() && !match; i++) {
                for ( int j = 0; j <  langs_avail.size(); j++) {
                    if (((String)(langs_user.get(i))).equals(
                            (String)(langs_avail.get(j)))) {
                        match = true;
                        break;
                    }
                }
            }
            if (match) {
                lang = (String)(langs_user.get(i - 1));
            } else {
                lang = def_lang;
            }
        }
        return lang;
}

Returns two character language code by checking environment in following order
1. Http request has parameter lang
2. Http session has parameter lang
3. Cookies has parameter lang
4. User locales has matching language we are providing
5. Otherwise we return default_lang from sitemap or if that is not found then 'en'

 public  void storeLang(Map objectModel,
    String lang) throws Exception 
{
        if (lang == null) {
            lang = DEFAULT_LANG;
        }
         Request request = ObjectModelHelper.getRequest(objectModel);
        if (storeInRequest) {
            request.setAttribute(PARAM_LANG, lang);
        }
        if (storeInSession) {
            // We do not create session here to keep this method static.
            // Session must be created outside if needed.
            Session session = request.getSession(false);
            // Try to store in a session.
            if (session != null) {
                synchronized (session) {
                    session.setAttribute(PARAM_LANG, lang);
                }
            }
            else {
                throw new Exception("LangSelect: session is not available.");
            }
        }
        if (storeInCookie) {
            Response response = ObjectModelHelper.getResponse(objectModel);
            Cookie langCookie = response.createCookie(PARAM_LANG, lang);
            response.addCookie(langCookie);
        }
}

Stores language code in the session or a cookie