    001// Copyright 2006, 2009, 2011 The Apache Software Foundation
    002//
    003// Licensed under the Apache License, Version 2.0 (the "License");
    004// you may not use this file except in compliance with the License.
    005// You may obtain a copy of the License at
    006//
    007//     http://www.apache.org/licenses/LICENSE-2.0
    008//
    009// Unless required by applicable law or agreed to in writing, software
    010// distributed under the License is distributed on an "AS IS" BASIS,
    011// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    012// See the License for the specific language governing permissions and
    013// limitations under the License.
    014
    015package org.apache.tapestry5.ioc.util;
    016
    017import org.apache.tapestry5.ioc.MessageFormatter;
    018import org.apache.tapestry5.ioc.Messages;
    019import org.apache.tapestry5.ioc.internal.util.CollectionFactory;
    020import org.apache.tapestry5.ioc.internal.util.MessageFormatterImpl;
    021
    022import java.util.Locale;
    023import java.util.Map;
    024
    025/**
    026 * Abstract implementation of {@link Messages} that doesn't know where values come from (that information is supplied in
    027 * a subclass, via the {@link #valueForKey(String)} method).
    028 */
    029public abstract class AbstractMessages implements Messages
    030{
    031    /**
    032     * String key to MF instance.
    033     */
    034    private final Map<String, MessageFormatter> cache = CollectionFactory.newConcurrentMap();
    035
    036    private final Locale locale;
    037
    038    protected AbstractMessages(Locale locale)
    039    {
    040        this.locale = locale;
    041    }
    042
    043    /**
    044     * Invoked to provide the value for a particular key. This may be invoked multiple times even for the same key. The
    045     * implementation should <em>ignore the case of the key</em>.
    046     *
    047     * @param key the key to obtain a value for (case insensitive)
    048     * @return the value for the key, or null if this instance can not provide the value
    049     */
    050    protected abstract String valueForKey(String key);
    051
    052
    053    @Override
    054    public boolean contains(String key)
    055    {
    056        return valueForKey(key) != null;
    057    }
    058
    059    @Override
    060    public String get(String key)
    061    {
    062        if (contains(key)) return valueForKey(key);
    063
    064        return String.format("[[missing key: %s]]", key);
    065    }
    066
    067    @Override
    068    public MessageFormatter getFormatter(String key)
    069    {
    070        MessageFormatter result = cache.get(key);
    071
    072        if (result == null)
    073        {
    074            result = buildMessageFormatter(key);
    075            cache.put(key, result);
    076        }
    077
    078        return result;
    079    }
    080
    081    private MessageFormatter buildMessageFormatter(String key)
    082    {
    083        String format = get(key);
    084
    085        return new MessageFormatterImpl(format, locale);
    086    }
    087
    088    @Override
    089    public String format(String key, Object... args)
    090    {
    091        return getFormatter(key).format(args);
    092    }
    093
    094}