001    /*
002     * Licensed to the Apache Software Foundation (ASF) under one
003     * or more contributor license agreements.  See the NOTICE file
004     * distributed with this work for additional information
005     * regarding copyright ownership.  The ASF licenses this file
006     * to you under the Apache License, Version 2.0 (the
007     * "License"); you may not use this file except in compliance
008     * with 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,
013     * software distributed under the License is distributed on an
014     * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
015     * KIND, either express or implied.  See the License for the
016     * specific language governing permissions and limitations
017     * under the License.
018     */
019    package org.apache.shiro.cache;
020    
021    import org.apache.shiro.util.CollectionUtils;
022    
023    import java.util.Collection;
024    import java.util.Collections;
025    import java.util.Map;
026    import java.util.Set;
027    
028    /**
029     * A <code>MapCache</code> is a {@link Cache Cache} implementation that uses a backing {@link Map} instance to store
030     * and retrieve cached data.
031     *
032     * @since 1.0
033     */
034    public class MapCache<K, V> implements Cache<K, V> {
035    
036        /**
037         * Backing instance.
038         */
039        private final Map<K, V> map;
040    
041        /**
042         * The name of this cache.
043         */
044        private final String name;
045    
046        public MapCache(String name, Map<K, V> backingMap) {
047            if (name == null) {
048                throw new IllegalArgumentException("Cache name cannot be null.");
049            }
050            if (backingMap == null) {
051                throw new IllegalArgumentException("Backing map cannot be null.");
052            }
053            this.name = name;
054            this.map = backingMap;
055        }
056    
057        public V get(K key) throws CacheException {
058            return map.get(key);
059        }
060    
061        public V put(K key, V value) throws CacheException {
062            return map.put(key, value);
063        }
064    
065        public V remove(K key) throws CacheException {
066            return map.remove(key);
067        }
068    
069        public void clear() throws CacheException {
070            map.clear();
071        }
072    
073        public int size() {
074            return map.size();
075        }
076    
077        public Set<K> keys() {
078            Set<K> keys = map.keySet();
079            if (!keys.isEmpty()) {
080                return Collections.unmodifiableSet(keys);
081            }
082            return Collections.emptySet();
083        }
084    
085        public Collection<V> values() {
086            Collection<V> values = map.values();
087            if (!CollectionUtils.isEmpty(values)) {
088                return Collections.unmodifiableCollection(values);
089            }
090            return Collections.emptySet();
091        }
092    
093        public String toString() {
094            return new StringBuilder("MapCache '")
095                    .append(name).append("' (")
096                    .append(map.size())
097                    .append(" entries)")
098                    .toString();
099        }
100    }