001    /**
002     *
003     * Licensed to the Apache Software Foundation (ASF) under one or more
004     * contributor license agreements.  See the NOTICE file distributed with
005     * this work for additional information regarding copyright ownership.
006     * The ASF licenses this file to You under the Apache License, Version 2.0
007     * (the "License"); you may not use this file except in compliance with
008     * the License.  You may obtain a copy of the License at
009     *
010     * http://www.apache.org/licenses/LICENSE-2.0
011     *
012     * Unless required by applicable law or agreed to in writing, software
013     * distributed under the License is distributed on an "AS IS" BASIS,
014     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015     * See the License for the specific language governing permissions and
016     * limitations under the License.
017     */
018    package org.apache.camel.util;
019    
020    import java.util.LinkedHashMap;
021    import java.util.Map;
022    
023    /**
024     * A Least Recently Used Cache
025     *
026     * @version $Revision: 1.1 $
027     */
028    public class LRUCache<K, V> extends LinkedHashMap<K, V> {
029        private static final long serialVersionUID = -342098639681884413L;
030        private int maxCacheSize = 10000;
031    
032        public LRUCache(int maximumCacheSize) {
033            this(maximumCacheSize, maximumCacheSize, 0.75f, true);
034        }
035    
036        /**
037         * Constructs an empty <tt>LRUCache</tt> instance with the
038         * specified initial capacity, maximumCacheSize,load factor and ordering mode.
039         *
040         * @param initialCapacity  the initial capacity.
041         * @param maximumCacheSize
042         * @param loadFactor       the load factor.
043         * @param accessOrder      the ordering mode - <tt>true</tt> for
044         *                         access-order, <tt>false</tt> for insertion-order.
045         * @throws IllegalArgumentException if the initial capacity is negative
046         *                                  or the load factor is nonpositive.
047         */
048        public LRUCache(int initialCapacity, int maximumCacheSize, float loadFactor, boolean accessOrder) {
049            super(initialCapacity, loadFactor, accessOrder);
050            this.maxCacheSize = maximumCacheSize;
051        }
052    
053        /**
054         * @return Returns the maxCacheSize.
055         */
056        public int getMaxCacheSize() {
057            return maxCacheSize;
058        }
059    
060        protected boolean removeEldestEntry(Map.Entry entry) {
061            return size() > maxCacheSize;
062        }
063    }