1 /*** 2 * 3 * Copyright 2004 Protique Ltd 4 * 5 * Licensed under the Apache License, Version 2.0 (the "License"); 6 * you may not use this file except in compliance with the License. 7 * You may obtain a copy of the License at 8 * 9 * http://www.apache.org/licenses/LICENSE-2.0 10 * 11 * Unless required by applicable law or agreed to in writing, software 12 * distributed under the License is distributed on an "AS IS" BASIS, 13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 14 * See the License for the specific language governing permissions and 15 * limitations under the License. 16 * 17 **/ 18 package org.codehaus.activemq.util; 19 20 import java.util.LinkedHashMap; 21 import java.util.Map; 22 23 /*** 24 * Represnts an LRUCache of a fixed maximum size which by default will 25 * remove items based on access order but can be used to use insertion order 26 * 27 * @version $Revision: 1.2 $ 28 */ 29 public class LRUCache extends LinkedHashMap { 30 private static final long serialVersionUID = -5754338187296859149L; 31 32 protected static final int DEFAULT_INITIAL_CAPACITY = 1000; 33 protected static final float DEFAULT_LOAD_FACTOR = (float) 0.75; 34 35 private int maxSize; 36 37 public LRUCache(int initialCapacity, float loadFactor, boolean accessOrder, int maxSize) { 38 super(initialCapacity, loadFactor, accessOrder); 39 this.maxSize = maxSize; 40 } 41 42 public LRUCache(int maxSize) { 43 this(DEFAULT_INITIAL_CAPACITY, DEFAULT_LOAD_FACTOR, true, maxSize); 44 } 45 46 public LRUCache(int maxSize, boolean accessOrder) { 47 this(DEFAULT_INITIAL_CAPACITY, DEFAULT_LOAD_FACTOR, accessOrder, maxSize); 48 } 49 50 protected boolean removeEldestEntry(Map.Entry eldest) { 51 return size() > maxSize; 52 } 53 }