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.activemq.memory; 018 019 import java.util.LinkedHashMap; 020 import java.util.Map; 021 022 /** 023 * A simple least-recently-used cache of a fixed size. 024 * 025 * @version $Revision:$ 026 */ 027 public class LRUMap<K,V> extends LinkedHashMap<K,V>{ 028 029 protected static final float DEFAULT_LOAD_FACTOR = (float) 0.75; 030 protected static final int DEFAULT_INITIAL_CAPACITY = 5000; 031 private static final long serialVersionUID = -9179676638408888162L; 032 033 private int maximumSize; 034 035 public LRUMap(int maximumSize) { 036 this(DEFAULT_INITIAL_CAPACITY, DEFAULT_LOAD_FACTOR, true, maximumSize); 037 } 038 039 public LRUMap(int maximumSize, boolean accessOrder) { 040 this(DEFAULT_INITIAL_CAPACITY, DEFAULT_LOAD_FACTOR, accessOrder, maximumSize); 041 } 042 043 public LRUMap(int initialCapacity, float loadFactor, boolean accessOrder, int maximumSize) { 044 super(initialCapacity, loadFactor, accessOrder); 045 this.maximumSize = maximumSize; 046 } 047 048 protected boolean removeEldestEntry(Map.Entry<K,V> eldest) { 049 return size() > maximumSize; 050 } 051 }