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 package org.apache.camel.util;
018
019 import java.util.LinkedHashMap;
020 import java.util.Map;
021
022 /**
023 * A Least Recently Used Cache
024 *
025 * @version $Revision: 747062 $
026 */
027 public class LRUCache<K, V> extends LinkedHashMap<K, V> {
028 private static final long serialVersionUID = -342098639681884413L;
029 private int maxCacheSize = 10000;
030
031 public LRUCache(int maximumCacheSize) {
032 this(maximumCacheSize, maximumCacheSize, 0.75f, true);
033 }
034
035 /**
036 * Constructs an empty <tt>LRUCache</tt> instance with the
037 * specified initial capacity, maximumCacheSize,load factor and ordering mode.
038 *
039 * @param initialCapacity the initial capacity.
040 * @param maximumCacheSize the max capacity.
041 * @param loadFactor the load factor.
042 * @param accessOrder the ordering mode - <tt>true</tt> for
043 * access-order, <tt>false</tt> for insertion-order.
044 * @throws IllegalArgumentException if the initial capacity is negative
045 * or the load factor is non positive.
046 */
047 public LRUCache(int initialCapacity, int maximumCacheSize, float loadFactor, boolean accessOrder) {
048 super(initialCapacity, loadFactor, accessOrder);
049 this.maxCacheSize = maximumCacheSize;
050 }
051
052 /**
053 * Returns the maxCacheSize.
054 */
055 public int getMaxCacheSize() {
056 return maxCacheSize;
057 }
058
059 protected boolean removeEldestEntry(Map.Entry entry) {
060 return size() > maxCacheSize;
061 }
062 }