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     */
017    
018    package org.apache.commons.configuration;
019    
020    import java.util.ArrayList;
021    import java.util.Iterator;
022    import java.util.List;
023    import java.util.Map;
024    
025    import org.apache.commons.collections.map.LinkedMap;
026    
027    /**
028     * Basic configuration classe. Stores the configuration data but does not
029     * provide any load or save functions. If you want to load your Configuration
030     * from a file use PropertiesConfiguration or XmlConfiguration.
031     *
032     * This class extends normal Java properties by adding the possibility
033     * to use the same key many times concatenating the value strings
034     * instead of overwriting them.
035     *
036     * @author <a href="mailto:stefano@apache.org">Stefano Mazzocchi</a>
037     * @author <a href="mailto:jon@latchkey.com">Jon S. Stevens</a>
038     * @author <a href="mailto:daveb@miceda-data">Dave Bryson</a>
039     * @author <a href="mailto:geirm@optonline.net">Geir Magnusson Jr.</a>
040     * @author <a href="mailto:leon@opticode.co.za">Leon Messerschmidt</a>
041     * @author <a href="mailto:kjohnson@transparent.com">Kent Johnson</a>
042     * @author <a href="mailto:dlr@finemaltcoding.com">Daniel Rall</a>
043     * @author <a href="mailto:ipriha@surfeu.fi">Ilkka Priha</a>
044     * @author <a href="mailto:jvanzyl@apache.org">Jason van Zyl</a>
045     * @author <a href="mailto:mpoeschl@marmot.at">Martin Poeschl</a>
046     * @author <a href="mailto:hps@intermeta.de">Henning P. Schmiedehausen</a>
047     * @author <a href="mailto:ksh@scand.com">Konstantin Shaposhnikov</a>
048     * @author <a href="mailto:oliver.heger@t-online.de">Oliver Heger</a>
049     * @version $Id: BaseConfiguration.java 529531 2007-04-17 08:52:41Z ebourg $
050     */
051    public class BaseConfiguration extends AbstractConfiguration implements Cloneable
052    {
053        /** stores the configuration key-value pairs */
054        private Map store = new LinkedMap();
055    
056        /**
057         * Adds a key/value pair to the map.  This routine does no magic morphing.
058         * It ensures the keylist is maintained
059         *
060         * @param key key to use for mapping
061         * @param value object to store
062         */
063        protected void addPropertyDirect(String key, Object value)
064        {
065            Object previousValue = getProperty(key);
066    
067            if (previousValue == null)
068            {
069                store.put(key, value);
070            }
071            else if (previousValue instanceof List)
072            {
073                // the value is added to the existing list
074                ((List) previousValue).add(value);
075            }
076            else
077            {
078                // the previous value is replaced by a list containing the previous value and the new value
079                List list = new ArrayList();
080                list.add(previousValue);
081                list.add(value);
082    
083                store.put(key, list);
084            }
085        }
086    
087        /**
088         * Read property from underlying map.
089         *
090         * @param key key to use for mapping
091         *
092         * @return object associated with the given configuration key.
093         */
094        public Object getProperty(String key)
095        {
096            return store.get(key);
097        }
098    
099        /**
100         * Check if the configuration is empty
101         *
102         * @return <code>true</code> if Configuration is empty,
103         * <code>false</code> otherwise.
104         */
105        public boolean isEmpty()
106        {
107            return store.isEmpty();
108        }
109    
110        /**
111         * check if the configuration contains the key
112         *
113         * @param key the configuration key
114         *
115         * @return <code>true</code> if Configuration contain given key,
116         * <code>false</code> otherwise.
117         */
118        public boolean containsKey(String key)
119        {
120            return store.containsKey(key);
121        }
122    
123        /**
124         * Clear a property in the configuration.
125         *
126         * @param key the key to remove along with corresponding value.
127         */
128        protected void clearPropertyDirect(String key)
129        {
130            if (containsKey(key))
131            {
132                store.remove(key);
133            }
134        }
135    
136        public void clear()
137        {
138            fireEvent(EVENT_CLEAR, null, null, true);
139            store.clear();
140            fireEvent(EVENT_CLEAR, null, null, false);
141        }
142    
143        /**
144         * Get the list of the keys contained in the configuration
145         * repository.
146         *
147         * @return An Iterator.
148         */
149        public Iterator getKeys()
150        {
151            return store.keySet().iterator();
152        }
153    
154        /**
155         * Creates a copy of this object. This implementation will create a deep
156         * clone, i.e. the map that stores the properties is cloned, too. So changes
157         * performed at the copy won't affect the original and vice versa.
158         *
159         * @return the copy
160         * @since 1.3
161         */
162        public Object clone()
163        {
164            try
165            {
166                BaseConfiguration copy = (BaseConfiguration) super.clone();
167                copy.store = (Map) ConfigurationUtils.clone(store);
168                return copy;
169            }
170            catch (CloneNotSupportedException cex)
171            {
172                // should not happen
173                throw new ConfigurationRuntimeException(cex);
174            }
175        }
176    }