jsf locale changer filter

LangFilter.java

package com.dominikdorn.lyrix.filters;

import javax.servlet.*;
import javax.servlet.annotation.WebFilter;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServletRequest;
import java.io.IOException;
import java.util.Locale;

/**
 * Filter for changing the locale of a request if a language cookie is present.
 */
public class LangFilter implements Filter {
    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
      // intentionally left blank as no initialization is needed
    }

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        if (servletRequest instanceof HttpServletRequest) {
            HttpServletRequest req = (HttpServletRequest) servletRequest;
// implement the logic you want here... set the locale by cookie or URL param or whatever you like
            Locale l = getSiteLang(req.getCookies());

            if (l != null) {
                filterChain.doFilter(new LocaleWrapper(req, l), servletResponse);
            } else {
                filterChain.doFilter(servletRequest, servletResponse);
            }

        } else {
            filterChain.doFilter(servletRequest, servletResponse);
        }
    }

    @Override
    public void destroy() {
    }


  /**
   * Returns the preferred Locale based on the given cookies
    * @param cookies an Array of Cookies
   * @return the preferred Locale, null if no cookie is found
   * or the cookies are null
   */
  public Locale getSiteLang(Cookie[] cookies) {
        if(cookies == null)
            return null;
        for (Cookie c : cookies) {
            if (c.getName().equals("siteLang")) {
                if (c.getValue().equals("de")) {
                    return Locale.GERMAN;
                }
                if (c.getValue().equals("en")) {
                    return Locale.ENGLISH;
                }
            }
        }
        return null;
    }

}

LocaleViewHandler.java

package com.dominikdorn.dc.viewhandlers;

import javax.faces.application.ViewHandler;
import javax.faces.application.ViewHandlerWrapper;
import javax.faces.context.FacesContext;
import java.util.Locale;

/**
 * This ViewHandler sets the Locale of the View to the locale given by the
 * HttpServletRequest. This is usually done in a ServletFilter
 * or a PhaseListener
 */
public class LocaleViewHandler extends ViewHandlerWrapper {

    ViewHandler parent;

    public LocaleViewHandler(ViewHandler parent) {
        this.parent = parent;
    }

    @Override
    public ViewHandler getWrapped() {
        return parent;
    }

    @Override
    /**
     * Simply delegates to the external Context (HttpServletContext)
     */
    public Locale calculateLocale(FacesContext context) {
        return context.getExternalContext().getRequestLocale();
    }
}

LocaleWrapper.java

package com.dominikdorn.lyrix.filters;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;
import java.util.*;

/**
 * Dominik Dorn
 * http://dominikdorn.com
 * http://twitter.com/domdorn
 */
public class LocaleWrapper extends HttpServletRequestWrapper {

    Locale l;
    Enumeration<Locale> e;

    public LocaleWrapper(HttpServletRequest request, Locale l) {
        super(request);
        this.l = l;

        Enumeration xe = super.getLocales();
        List<Locale> list = new ArrayList<Locale>();
        list.add(l);
        list.addAll(Collections.list(xe));
        e = Collections.enumeration(list);
    }

    @Override
    public Locale getLocale() {
        return l;
    }

    @Override
    public Enumeration<Locale> getLocales() {
        return e;
    }
}

WEB-INF_faces-config.xml

<?xml version='1.0' encoding='UTF-8'?>

<!-- =========== FULL CONFIGURATION FILE ================================== -->

<faces-config version="2.0"
              xmlns="http://java.sun.com/xml/ns/javaee"
              xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
              xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-facesconfig_2_0.xsd">

    <application>
        <resource-bundle>
            <base-name>messages</base-name>
            <var>msg</var>
        </resource-bundle>
        <locale-config>
            <default-locale>de</default-locale>
            <supported-locale>de</supported-locale>
            <supported-locale>en</supported-locale>
        </locale-config>
        <view-handler>com.dominikdorn.dc.viewhandlers.LocaleViewHandler</view-handler>
    </application>
</faces-config>

WEB-INF_web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app
        xmlns="http://java.sun.com/xml/ns/javaee"
        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"

         version="3.0">

    <filter>
        <filter-name>Pretty Filter</filter-name>
        <filter-class>com.ocpsoft.pretty.PrettyFilter</filter-class>
    </filter>

    <filter>
        <filter-name>LangFilter</filter-name>
        <filter-class>com.dominikdorn.lyrix.filters.LangFilter</filter-class>
    </filter>

    <filter-mapping>
        <filter-name>Pretty Filter</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>

    <filter-mapping>
        <filter-name>LangFilter</filter-name>
        <url-pattern>/*</url-pattern>
        <dispatcher>ERROR</dispatcher>
        <dispatcher>REQUEST</dispatcher>
    </filter-mapping>

</web-app>