/* * Copyright 2001-2004 The Apache Software Foundation. *  * Licensed 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.logging.impl;import java.util.Enumeration;import java.util.Hashtable;import java.util.Vector;import org.apache.commons.logging.Log;import org.apache.commons.logging.LogConfigurationException;import org.apache.commons.logging.LogFactory;import org.apache.log4j.Logger;/** * <p>Concrete subclass of {@link LogFactory} specific to log4j. * * @deprecated Per discussion on COMMONS-DEV, the behind-the-scenes use *  of this class as a proxy factory has been removed.  For 1.0, you *  can still request it directly if you wish, but it doesn't really *  do anything useful, and will be removed in 1.1. * * @author Costin Manolache */public final class Log4jFactory extends LogFactory {    public Log4jFactory() {        super();    }    /**     * The configuration attributes for this {@link LogFactory}.     */    private Hashtable attributes = new Hashtable();    // Previously returned instances, to avoid creation of proxies    private Hashtable instances = new Hashtable();    // --------------------------------------------------------- Public Methods    /**     * Return the configuration attribute with the specified name (if any),     * or <code>null</code> if there is no such attribute.     *     * @param name Name of the attribute to return     */    public Object getAttribute(String name) {        return (attributes.get(name));    }    /**     * Return an array containing the names of all currently defined     * configuration attributes.  If there are no such attributes, a zero     * length array is returned.     */    public String[] getAttributeNames() {        Vector names = new Vector();        Enumeration keys = attributes.keys();        while (keys.hasMoreElements()) {            names.addElement((String) keys.nextElement());        }        String results[] = new String[names.size()];        for (int i = 0; i < results.length; i++) {            results[i] = (String) names.elementAt(i);        }        return (results);    }    /**     * Convenience method to derive a name from the specified class and     * call <code>getInstance(String)</code> with it.     *     * @param clazz Class for which a suitable Log name will be derived     *     * @exception LogConfigurationException if a suitable <code>Log</code>     *  instance cannot be returned     */    public Log getInstance(Class clazz)        throws LogConfigurationException    {        Log instance = (Log) instances.get(clazz);        if( instance != null )            return instance;        instance=new Log4JLogger( Logger.getLogger( clazz ));        instances.put( clazz, instance );        return instance;    }    public Log getInstance(String name)        throws LogConfigurationException    {        Log instance = (Log) instances.get(name);        if( instance != null )            return instance;        instance=new Log4JLogger( Logger.getLogger( name ));        instances.put( name, instance );        return instance;    }    /**     * Release any internal references to previously created {@link Log}     * instances returned by this factory.  This is useful in environments     * like servlet containers, which implement application reloading by     * throwing away a ClassLoader.  Dangling references to objects in that     * class loader would prevent garbage collection.     */    public void release() {        instances.clear();        // what's the log4j mechanism to cleanup ???    }    /**     * Remove any configuration attribute associated with the specified name.     * If there is no such attribute, no action is taken.     *     * @param name Name of the attribute to remove     */    public void removeAttribute(String name) {        attributes.remove(name);    }    /**     * Set the configuration attribute with the specified name.  Calling     * this with a <code>null</code> value is equivalent to calling     * <code>removeAttribute(name)</code>.     *     * @param name Name of the attribute to set     * @param value Value of the attribute to set, or <code>null</code>     *  to remove any setting for this attribute     */    public void setAttribute(String name, Object value) {        if (value == null) {            attributes.remove(name);        } else {            attributes.put(name, value);        }    }}