Java tutorial
/* * Licensed to the Apache Software Foundation (ASF) under one * or more contributor license agreements. See the NOTICE file * distributed with this work for additional information * regarding copyright ownership. The ASF licenses this file * to you under the Apache License, Version 2.0 (the * "License"); you may not use this file except in compliance * with the License. You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, * software distributed under the License is distributed on an * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY * KIND, either express or implied. See the License for the * specific language governing permissions and limitations * under the License. */ package org.jsecurity.mgt; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.jsecurity.cache.CacheManager; import org.jsecurity.cache.CacheManagerAware; import org.jsecurity.cache.ehcache.EhCacheManager; import org.jsecurity.util.Destroyable; import org.jsecurity.util.LifecycleUtils; /** * A very basic extension point for the SecurityManager interface that merely provides logging and caching * support. All <tt>SecurityManager</tt> method implementations are left to subclasses. * * <p>Upon instantiation, a sensible default {@link CacheManager CacheManager} will be attempt to be created * automatically by the {@link #ensureCacheManager() ensureCacheManager()} method. This <code>CacheManager</code> * can then be used by subclass implementations and children components for use to achieve better application * performance. * * @author Les Hazlewood * @author Jeremy Haile * @since 0.9 */ public abstract class CachingSecurityManager implements SecurityManager, Destroyable, CacheManagerAware { /** * Internal private static log instance. */ private static final Log log = LogFactory.getLog(CachingSecurityManager.class); /** * The CacheManager to use to perform caching operations to enhance performance. Can be null. */ protected CacheManager cacheManager; /** * Default no-arg constructor that will automatically attempt to initialize a default cacheManager */ public CachingSecurityManager() { ensureCacheManager(); } /** * Returns the CacheManager used by this SecurityManager. * * @return the cacheManager used by this SecurityManager */ public CacheManager getCacheManager() { return cacheManager; } /** * Sets the CacheManager used by this <code>SecurityManager</code> and potentially any of its * children components. * <p/> * After the cacheManager attribute has been set, the template method * {@link #afterCacheManagerSet afterCacheManagerSet()} is executed to allow subclasses to adjust when a * cacheManager is available. * * @param cacheManager the CacheManager used by this <code>SecurityManager</code> and potentially any of its * children components. */ public void setCacheManager(CacheManager cacheManager) { this.cacheManager = cacheManager; afterCacheManagerSet(); } /** * Simple lazy-initialization method that checks to see if a * {@link #setCacheManager(org.jsecurity.cache.CacheManager) cacheManager} has been set, and if not, * attempts to {@link #createCacheManager() create one} and uses that to set the class attribute. * <p/> * The default implementation functions as follows: * <pre><code> * CacheManager cm = getCacheManager(); * if (cm == null) { * cm = createCacheManager(); * if (cm != null) { * setCacheManager(cm); * } * }</code></pre> */ protected void ensureCacheManager() { CacheManager cm = getCacheManager(); if (cm == null) { cm = createCacheManager(); if (cm != null) { setCacheManager(cm); } } } /** * Template callback to notify subclasses that a * {@link CacheManager CacheManager} has been set and is available for use via the * {@link #getCacheManager getCacheManager()} method. */ protected void afterCacheManagerSet() { } /** * Creates a {@link CacheManager CacheManager} instance to be used by this <code>SecurityManager</code> * and potentially any of its children components. * <p/> * This default implementation attempts to create an {@link EhCacheManager EhCacheManager}, assuming that * ehcache is in the classpath. If Ehcache is not in the classpath, no cache manager will be created and this * method does nothing. * <p/> * This can be overridden by subclasses for a different implementation, but it is often easier to set a * different implementation via the {@link #setCacheManager(org.jsecurity.cache.CacheManager) setCacheManager} * method, for example in code or Dependency Injection frameworks (a la Spring or JEE 3). * * @return a newly created <code>CacheManager</code> instance. * @see #ensureCacheManager() ensureCacheManager() */ protected CacheManager createCacheManager() { CacheManager manager = null; if (log.isDebugEnabled()) { log.debug("Attempting to initialize default CacheManager using EhCache..."); } try { EhCacheManager ehCacheManager = new EhCacheManager(); ehCacheManager.init(); manager = ehCacheManager; } catch (NoClassDefFoundError e) { if (log.isDebugEnabled()) { log.debug("Ehcache was not found in the classpath. A default EhCacheManager cannot be created."); } } return manager; } /** * First calls {@link #beforeCacheManagerDestroyed() beforeCacheManagerDestroyed()} to allow subclasses to clean up * first, then calls {@link #destroyCacheManager() destroyCacheManager()} to clean up the internal * {@link CacheManager CacheManager}. */ public void destroy() { beforeCacheManagerDestroyed(); destroyCacheManager(); } /** * Template hook for subclasses to perform cleanup behavior during shutdown. */ protected void beforeCacheManagerDestroyed() { } /** * Cleans up the internal <code>CacheManager</code> instance during shutdown. */ protected void destroyCacheManager() { LifecycleUtils.destroy(getCacheManager()); } }