/* * Copyright (c) 2005, John Mettraux, OpenWFE.org * All rights reserved. *  * Redistribution and use in source and binary forms, with or without  * modification, are permitted provided that the following conditions are met: *  * . Redistributions of source code must retain the above copyright notice, this *   list of conditions and the following disclaimer.   *  * . Redistributions in binary form must reproduce the above copyright notice,  *   this list of conditions and the following disclaimer in the documentation  *   and/or other materials provided with the distribution. *  * . Neither the name of the "OpenWFE" nor the names of its contributors may be *   used to endorse or promote products derived from this software without *   specific prior written permission. *  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE  * POSSIBILITY OF SUCH DAMAGE. * * $Id: Cache.java,v 1.15 2005/05/17 16:40:12 jmettraux Exp $ *///// Cache.java//// jmettraux@openwfe.org//// generated with // jtmpl 1.0.04 20.11.2001 John Mettraux (jmettraux@openwfe.org)//package openwfe.org;import openwfe.org.xml.XmlUtils;/** * A cache implementation : it's in fact a map with a max capacity. * When you put an item in a cache that is full, the least recently used item * will be thrown out to give its place to the incoming item. * * <p><font size=2>CVS Info : * <br>$Author: jmettraux $ * <br>$Date: 2005/05/17 16:40:12 $ * <br>$Id: Cache.java,v 1.15 2005/05/17 16:40:12 jmettraux Exp $ </font> * * @author jmettraux@openwfe.org */public class Cache{    /*    private final static org.apache.log4j.Logger log = org.apache.log4j.Logger        .getLogger(Cache.class.getName());    */    //    // FIELDS    private java.util.Map cache = new java.util.HashMap();    private java.util.List lru = new java.util.ArrayList(0);    private int maxSize = 100;    //    // CONSTRUCTORS    /**     * Builds a cache with a custom maxSize.     */    public Cache (final int maxSize)    {        super();        if (maxSize < 1)         {            throw new IllegalArgumentException                ("Cannot build a cache with a maxSize < 1 : "+maxSize);        }        this.maxSize = maxSize;    }    /**     * Builds a cache with the default capacity (maxSize set to 100).     */    public Cache ()    {        super();    }    //    // METHODS    /**     * Like the get() method of a Map.     */    public synchronized Object get (final Object key)    {        Object result = this.cache.get(key);        if (result != null)        {            if (this.lru.contains(key)) this.lru.remove(key);            this.lru.add(0, key);        }        adjust();        return result;    }    /**     * Like the remove() method of a Map.     */    public synchronized void remove (final Object key)    {        this.cache.remove(key);        this.lru.remove(key);    }    /**     * Like the put() method of a Map.     */    public synchronized void put (final Object key, final Object value)    {        this.cache.put(key, value);        this.lru.add(0, key);        adjust();    }    private void adjust()    {        while (this.lru.size() > maxSize)        {            Object key = this.lru.remove(this.lru.size()-1);            this.cache.remove(key);        }    }    /**     * Returns the count of items currently stored in this cache.     */    public int size ()    {        return this.cache.size();    }    /**     * Returns the capacity attributed to this cache.     */    public int getMaxSize ()    {        return this.maxSize;    }    /**     * Beware : you have to handle sync by yourself     */    public java.util.Iterator iterator ()    {        return this.cache.values().iterator();    }    /**     * Like the keySet() method of a Map.     */    public java.util.Set keySet ()    {        return this.cache.keySet();    }    /**     * This method is used by the getStatus() method of services      * using a cache     */    public org.jdom.Element getStatus ()    {        org.jdom.Element cacheElt = new org.jdom.Element("cache");        cacheElt.addContent(XmlUtils.getRevisionElt("$Id: Cache.java,v 1.15 2005/05/17 16:40:12 jmettraux Exp $"));        java.util.Iterator it = this.cache.keySet().iterator();        while (it.hasNext())        {            org.jdom.Element keyElt = new org.jdom.Element("key");            keyElt.addContent(it.next().toString());            cacheElt.addContent(keyElt);        }        return cacheElt;    }}