001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.apache.commons.discovery.resource.names;
018
019import java.util.Hashtable;
020import java.util.Map;
021
022import org.apache.commons.discovery.ResourceNameDiscover;
023import org.apache.commons.discovery.ResourceNameIterator;
024import org.apache.commons.logging.Log;
025import org.apache.commons.logging.LogFactory;
026
027/**
028 * Recover resource name from Managed Properties,
029 * using OLD property names.
030 * 
031 * This class maintains a mapping between old names and
032 * (new) the class names they represent.  The discovery
033 * mechanism uses the class names as property names.
034 * 
035 * @see org.apache.commons.discovery.tools.ManagedProperties
036 */
037public class DiscoverMappedNames extends ResourceNameDiscoverImpl implements ResourceNameDiscover {
038
039    private static Log log = LogFactory.getLog(DiscoverMappedNames.class);
040
041    /**
042     * Sets the {@code Log} for this class.
043     *
044     * @param _log This class {@code Log}
045     * @deprecated This method is not thread-safe
046     */
047    @Deprecated
048    public static void setLog(Log _log) {
049        log = _log;
050    }
051
052    /**
053     * The String name ==> String[] newNames mapping
054     */
055    private final Map<String, String[]> mapping = new Hashtable<String, String[]>();
056
057    /**
058     * Construct a new resource discoverer
059     */
060    public DiscoverMappedNames() {
061    }
062
063    /**
064     * Maps a name to another name.
065     *
066     * @param fromName The name has to be mapped
067     * @param toName The mapping target
068     */
069    public void map(String fromName, String toName) {
070        map(fromName, new String[]{ toName });
071    }
072
073    /**
074     * Maps a name to multiple names.
075     *
076     * @param fromName The name has to be mapped
077     * @param toNames The mapping targets
078     */
079    public void map(String fromName, String [] toNames) {
080        mapping.put(fromName, toNames);
081    }
082
083    /**
084     * {@inheritDoc}
085     */
086    @Override
087    public ResourceNameIterator findResourceNames(final String resourceName) {
088        if (log.isDebugEnabled()) {
089            log.debug("find: resourceName='" + resourceName + "', mapping to constants");
090        }
091
092        final String[] names = mapping.get(resourceName);
093
094        return new ResourceNameIterator() {
095
096            private int idx = 0;
097
098            public boolean hasNext() {
099                if (names != null) {
100                    while (idx < names.length  &&  names[idx] == null) {
101                        idx++;
102                    }
103                    return idx < names.length;
104                }
105                return false;
106            }
107
108            public String nextResourceName() {
109                return hasNext() ? names[idx++] : null;
110            }
111        };
112    }
113
114}