    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
    015    package org.apache.tapestry5.ioc.util;
    016
    017    import org.apache.tapestry5.ioc.MessageFormatter;
    018    import org.apache.tapestry5.ioc.Messages;
    019    import org.apache.tapestry5.ioc.internal.util.CollectionFactory;
    020    import org.apache.tapestry5.ioc.internal.util.MessageFormatterImpl;
    021
    022    import java.util.Locale;
    023    import 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     */
    029    public 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        public boolean contains(String key)
    054        {
    055            return valueForKey(key) != null;
    056        }
    057
    058        public String get(String key)
    059        {
    060            if (contains(key)) return valueForKey(key);
    061
    062            return String.format("[[missing key: %s]]", key);
    063        }
    064
    065        public MessageFormatter getFormatter(String key)
    066        {
    067            MessageFormatter result = cache.get(key);
    068
    069            if (result == null)
    070            {
    071                result = buildMessageFormatter(key);
    072                cache.put(key, result);
    073            }
    074
    075            return result;
    076        }
    077
    078        private MessageFormatter buildMessageFormatter(String key)
    079        {
    080            String format = get(key);
    081
    082            return new MessageFormatterImpl(format, locale);
    083        }
    084
    085        public String format(String key, Object... args)
    086        {
    087            return getFormatter(key).format(args);
    088        }
    089
    090    }