Get all available values of @RequestMapping from controller in filter

I am writing an application using java and Spring MVC. My scope is that my URL would contain language smth like http://localhost:8080/School/en/xxx/... . In my application I use next code:

controller-servlet.xml

<bean id="localeResolver" class="org.springframework.web.servlet.i18n.SessionLocaleResolver"/>

web.xml

<filter>
    <filter-name>URLFilter</filter-name>
    <filter-class>filter.URLFilter</filter-class>
</filter>
<filter-mapping>
    <filter-name>URLFilter</filter-name>
    <url-pattern>/*</url-pattern>
</filter-mapping>

Filter

public void doFilter(ServletRequest hsRequest, ServletResponse hsResponse, FilterChain filterChain) throws IOException, ServletException {
    final HttpServletRequest request = (HttpServletRequest) hsRequest;
    final HttpServletResponse response = (HttpServletResponse) hsResponse;

    String servletPath = request.getRequestURI().substring(request.getContextPath().length());
    List<String> langList = new ArrayList<String>();
    langList.add("/it/");
    langList.add("/en/");
    for (String lang : langList) {
        if (StringUtils.startsWithIgnoreCase(servletPath, lang)) {
            filterChain.doFilter(hsRequest, hsResponse);
            return;
        }
    }
    String string = request.getContextPath() + "/en".concat(servletPath);
    response.sendRedirect(string);
}

Interceptor:

public class LangInterceptor extends HandlerInterceptorAdapter {

@Autowired
SessionLocaleResolver sessionLocaleResolver;

@Override
public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
    String language = request.getServletPath().substring(1, 3);
    Locale locale = new Locale(language);
    sessionLocaleResolver.setLocale(request, response, locale);
    return true;
}

I suppose next behavior:

1. User introduces URL like: "httр://localhost:8080/School/" - filter doesn't find any "/it/" or "/en/" and add by default "/en/" than redirect to httр://localhost:8080/School/en/ where next time will find that is OK.
2. User introduces URL like: httр://localhost:8080/School/add - filter doesn't find any "/it/" or "/en/" and add by default "/en/" after redirect to httр://localhost:8080/School/en/add where find such URL that is OK.
3. User introduces URL like: httр://localhost:8080/School/en1/add - filter doesn't find any "/it/" or "/en/" and add by default "/en/" after redirect to httр://localhost:8080/School/en/en1/add where doesn't find such URL and redirect to 404.jsp that is NOT OK.

So before redirect I need to verify what follows in url after "/en"/, so I need a list of values of @RequestMapping of @Controller. I tried to use RequestMappingHandlerMapping but it is impossible because at filter level beans are not initialized.

How can I solve this problem?