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: 1.1 $
28 */
29 public class LRUCache extends LinkedHashMap {
30 protected static final int DEFAULT_INITIAL_CAPACITY = 1000;
31 protected static final float DEFAULT_LOAD_FACTOR = (float) 0.75;
32
33 private int maxSize;
34
35 public LRUCache(int initialCapacity, float loadFactor, boolean accessOrder, int maxSize) {
36 super(initialCapacity, loadFactor, accessOrder);
37 this.maxSize = maxSize;
38 }
39
40 public LRUCache(int maxSize) {
41 this(DEFAULT_INITIAL_CAPACITY, DEFAULT_LOAD_FACTOR, true, maxSize);
42 }
43
44 public LRUCache(int maxSize, boolean accessOrder) {
45 this(DEFAULT_INITIAL_CAPACITY, DEFAULT_LOAD_FACTOR, accessOrder, maxSize);
46 }
47
48 protected boolean removeEldestEntry(Map.Entry eldest) {
49 return size() > maxSize;
50 }
51 }