a Wicket Mapper that sets the locale based on the hostname of the request

gistfile1.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.example;

import org.apache.wicket.examples.requestmapper.LocaleHelper;
import org.apache.wicket.Session;
import org.apache.wicket.request.IRequestHandler;
import org.apache.wicket.request.IRequestMapper;
import org.apache.wicket.request.Request;
import org.apache.wicket.request.Url;
import org.apache.wicket.request.mapper.AbstractComponentMapper;
import org.apache.wicket.util.string.Strings;

import java.util.Locale;

/**
 * A modification of LocaleFirstMapper that uses the hostname of the Request to infer and set the user's locale.
 *
 * see: http://www.wicket-library.com/wicket-examples/mappers/en_US
 *
 * @author ivaynberg
 * @author matej.knopp
 * @author george armhold
 */
public class LocaleFromHostnameMapper extends AbstractComponentMapper
{
    /**
     * the base hostname, without any locale prefix, i.e. "example.com"
     */
    private String baseHostName;

    private final IRequestMapper chain;

    /**
     * Construct.
     *
     * @param chain
     */
    public LocaleFromHostnameMapper(final IRequestMapper chain, String baseHostName)
    {
        this.chain = chain;
        this.baseHostName = baseHostName;
    }

    /**
     * @see org.apache.wicket.request.IRequestMapper#getCompatibilityScore(org.apache.wicket.request.Request)
     */
    public int getCompatibilityScore(Request request)
    {
        if (getLocaleFromUrl(request) != null)
        {
            request = stripLocaleSegment(request);
        }

        // since we match all urls the score is simply delegated to the chain
        return chain.getCompatibilityScore(request);
    }

    private Request stripLocaleSegment(Request request)
    {
        Url url = request.getUrl();
//        url.getSegments().remove(0);
        url.setHost(baseHostName);
        return request.cloneWithUrl(url);
    }

    private Locale getLocaleFromUrl(Request request)
    {
        String host = request.getClientUrl().getHost();
        if (host == null) host = "";

        int langEnd = host.indexOf("." + baseHostName);
        if (langEnd > 0)
        {
            String localeAsString = host.substring(0, langEnd);
            if (!Strings.isEmpty(localeAsString))
            {
                return LocaleHelper.parseLocale(localeAsString);
            }
        }
        
        return null;
    }

    /**
     * @see org.apache.wicket.request.IRequestMapper#mapRequest(org.apache.wicket.request.Request)
     */
    public IRequestHandler mapRequest(Request request)
    {
        Locale locale = getLocaleFromUrl(request);
        if (locale != null)
        {
            Session.get().setLocale(locale);

            // now that we have proccessed the first segment we need to strip from the url
            request = stripLocaleSegment(request);
        }

        // chain url processing
        return chain.mapRequest(request);
    }

    /**
     * @see org.apache.wicket.request.IRequestMapper#mapHandler(org.apache.wicket.request.IRequestHandler)
     */
    public Url mapHandler(IRequestHandler handler)
    {
        // let the chain create the url
        Url url = chain.mapHandler(handler);

        if (url != null)
        {
            Locale locale = Session.get().getLocale();
            if (locale == null)
            {
                locale = Locale.US;
            }
//            url.getSegments().add(0, locale.toString());
            url.setHost(locale.getLanguage() + "." + baseHostName);
        }

        return url;
    }


}