BaseConfiguration.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 org.apache.commons.configuration;

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.Map;

import org.apache.commons.collections.map.LinkedMap;

/**
 * Basic configuration classe. Stores the configuration data but does not
 * provide any load or save functions. If you want to load your Configuration
 * from a file use PropertiesConfiguration or XmlConfiguration.
 *
 * This class extends normal Java properties by adding the possibility
 * to use the same key many times concatenating the value strings
 * instead of overwriting them.
 *
 * @author <a href="mailto:stefano@apache.org">Stefano Mazzocchi</a>
 * @author <a href="mailto:jon@latchkey.com">Jon S. Stevens</a>
 * @author <a href="mailto:daveb@miceda-data">Dave Bryson</a>
 * @author <a href="mailto:geirm@optonline.net">Geir Magnusson Jr.</a>
 * @author <a href="mailto:leon@opticode.co.za">Leon Messerschmidt</a>
 * @author <a href="mailto:kjohnson@transparent.com">Kent Johnson</a>
 * @author <a href="mailto:dlr@finemaltcoding.com">Daniel Rall</a>
 * @author <a href="mailto:ipriha@surfeu.fi">Ilkka Priha</a>
 * @author <a href="mailto:jvanzyl@apache.org">Jason van Zyl</a>
 * @author <a href="mailto:mpoeschl@marmot.at">Martin Poeschl</a>
 * @author <a href="mailto:hps@intermeta.de">Henning P. Schmiedehausen</a>
 * @author <a href="mailto:ksh@scand.com">Konstantin Shaposhnikov</a>
 * @author <a href="mailto:oliver.heger@t-online.de">Oliver Heger</a>
 * @version $Id: BaseConfiguration.java 529531 2007-04-17 08:52:41Z ebourg $
 */
public class BaseConfiguration extends AbstractConfiguration implements Cloneable
{
    /** stores the configuration key-value pairs */
    private Map store = new LinkedMap();

    /**
     * Adds a key/value pair to the map.  This routine does no magic morphing.
     * It ensures the keylist is maintained
     *
     * @param key key to use for mapping
     * @param value object to store
     */
    protected void addPropertyDirect(String key, Object value)
    {
        Object previousValue = getProperty(key);

        if (previousValue == null)
        {
            store.put(key, value);
        }
        else if (previousValue instanceof List)
        {
            // the value is added to the existing list
            ((List) previousValue).add(value);
        }
        else
        {
            // the previous value is replaced by a list containing the previous value and the new value
            List list = new ArrayList();
            list.add(previousValue);
            list.add(value);

            store.put(key, list);
        }
    }

    /**
     * Read property from underlying map.
     *
     * @param key key to use for mapping
     *
     * @return object associated with the given configuration key.
     */
    public Object getProperty(String key)
    {
        return store.get(key);
    }

    /**
     * Check if the configuration is empty
     *
     * @return <code>true</code> if Configuration is empty,
     * <code>false</code> otherwise.
     */
    public boolean isEmpty()
    {
        return store.isEmpty();
    }

    /**
     * check if the configuration contains the key
     *
     * @param key the configuration key
     *
     * @return <code>true</code> if Configuration contain given key,
     * <code>false</code> otherwise.
     */
    public boolean containsKey(String key)
    {
        return store.containsKey(key);
    }

    /**
     * Clear a property in the configuration.
     *
     * @param key the key to remove along with corresponding value.
     */
    protected void clearPropertyDirect(String key)
    {
        if (containsKey(key))
        {
            store.remove(key);
        }
    }

    public void clear()
    {
        fireEvent(EVENT_CLEAR, null, null, true);
        store.clear();
        fireEvent(EVENT_CLEAR, null, null, false);
    }

    /**
     * Get the list of the keys contained in the configuration
     * repository.
     *
     * @return An Iterator.
     */
    public Iterator getKeys()
    {
        return store.keySet().iterator();
    }

    /**
     * Creates a copy of this object. This implementation will create a deep
     * clone, i.e. the map that stores the properties is cloned, too. So changes
     * performed at the copy won't affect the original and vice versa.
     *
     * @return the copy
     * @since 1.3
     */
    public Object clone()
    {
        try
        {
            BaseConfiguration copy = (BaseConfiguration) super.clone();
            copy.store = (Map) ConfigurationUtils.clone(store);
            return copy;
        }
        catch (CloneNotSupportedException cex)
        {
            // should not happen
            throw new ConfigurationRuntimeException(cex);
        }
    }
}