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 java.util.Collection;
022 import java.util.Set;
023
024 /**
025 * A Cache efficiently stores temporary objects primarily to improve an application's performance.
026 *
027 * <p>Shiro doesn't implement a full Cache mechanism itself, since that is outside the core competency of a
028 * Security framework. Instead, this interface provides an abstraction (wrapper) API on top of an underlying
029 * cache framework's cache instance (e.g. JCache, Ehcache, JCS, OSCache, JBossCache, TerraCotta, Coherence,
030 * GigaSpaces, etc, etc), allowing a Shiro user to configure any cache mechanism they choose.
031 *
032 * @author Les Hazlewood
033 * @author Jeremy Haile
034 * @since 0.2
035 */
036 public interface Cache<K, V> {
037
038 /**
039 * Returns the Cached value stored under the specified {@code key} or
040 * {@code null} if there is no Cache entry for that {@code key}.
041 *
042 * @param key the key that the value was previous added with
043 * @return the cached object or {@code null} if there is no entry for the specified {@code key}
044 * @throws CacheException if there is a problem accessing the underlying cache system
045 */
046 public V get(K key) throws CacheException;
047
048 /**
049 * Adds a Cache entry.
050 *
051 * @param key the key used to identify the object being stored.
052 * @param value the value to be stored in the cache.
053 * @return the previous value associated with the given {@code key} or {@code null} if there was previous value
054 * @throws CacheException if there is a problem accessing the underlying cache system
055 */
056 public V put(K key, V value) throws CacheException;
057
058 /**
059 * Remove the cache entry corresponding to the specified key.
060 *
061 * @param key the key of the entry to be removed.
062 * @return the previous value associated with the given {@code key} or {@code null} if there was previous value
063 * @throws CacheException if there is a problem accessing the underlying cache system
064 */
065 public V remove(K key) throws CacheException;
066
067 /**
068 * Clear all entries from the cache.
069 *
070 * @throws CacheException if there is a problem accessing the underlying cache system
071 */
072 public void clear() throws CacheException;
073
074 /**
075 * Returns the number of entries in the cache.
076 *
077 * @return the number of entries in the cache.
078 */
079 public int size();
080
081 /**
082 * Returns a view of all the keys for entries contained in this cache.
083 *
084 * @return a view of all the keys for entries contained in this cache.
085 */
086 public Set<K> keys();
087
088 /**
089 * Returns a view of all of the values contained in this cache.
090 *
091 * @return a view of all of the values contained in this cache.
092 */
093 public Collection<V> values();
094 }