Java tutorial
package org.jboss.seam.wiki.util; import org.hibernate.cache.*; //$Id: MonitoringEHCacheProvider.java 4779 2007-04-27 10:34:44Z cbauer $ /** * Copyright 2003-2006 Greg Luck, Jboss Inc * * Licensed 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. */ import java.util.Properties; import java.net.URL; import java.lang.management.ManagementFactory; import net.sf.ehcache.CacheManager; import net.sf.ehcache.management.ManagementService; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.hibernate.cfg.Environment; import org.hibernate.util.StringHelper; import org.hibernate.util.ConfigHelper; import javax.management.MBeanServer; /** * Cache Provider plugin for Hibernate * * Use <code>hibernate.cache.provider_class=org.hibernate.cache.EhCacheProvider</code> * in Hibernate 3.x or later * * Taken from EhCache 0.9 distribution * @author Greg Luck * @author Emmanuel Bernard * */ /** * Cache Provider plugin for ehcache-1.2. New in this provider are ehcache support for multiple * Hibernate session factories, each with its own ehcache configuration, and non Serializable keys and values. * Ehcache-1.2 also has many other features such as cluster support and listeners, which can be used seamlessly simply * by configurion in ehcache.xml. * <p/> * Use <code>hibernate.cache.provider_class=org.hibernate.cache.EhCacheProvider</code> in the Hibernate configuration * to enable this provider for Hibernate's second level cache. * <p/> * When configuring multiple ehcache CacheManagers, as you would where you have multiple Hibernate Configurations and * multiple SessionFactories, specify in each Hibernate configuration the ehcache configuration using * the property <code>hibernate.cache.provider_configuration_file_resource_path</code> An example to set an ehcache configuration * called ehcache-2.xml would be <code>hibernate.cache.provider_configuration_file_resource_path=/ehcache-2.xml</code>. If the leading * slash is not there one will be added. The configuration file will be looked for in the root of the classpath. * <p/> * Updated for ehcache-1.2. Note this provider requires ehcache-1.2.jar. Make sure ehcache-1.1.jar or earlier * is not in the classpath or it will not work. * <p/> * Added monitoring capabilities with JMX registration, now requires ehcache-1.3! * @author Christian Bauer * <p/> * See http://ehcache.sf.net for documentation on ehcache * <p/> * * @author Greg Luck * @author Emmanuel Bernard */ public class MonitoringEHCacheProvider implements CacheProvider { private static final Log log = LogFactory.getLog(MonitoringEHCacheProvider.class); private CacheManager manager; /** * Builds a Cache. * <p> * Even though this method provides properties, they are not used. * Properties for EHCache are specified in the ehcache.xml file. * Configuration will be read from ehcache.xml for a cache declaration * where the name attribute matches the name parameter in this builder. * * @param name the name of the cache. Must match a cache configured in ehcache.xml * @param properties not used * @return a newly built cache will be built and initialised * @throws CacheException inter alia, if a cache of the same name already exists */ public Cache buildCache(String name, Properties properties) throws CacheException { try { net.sf.ehcache.Cache cache = manager.getCache(name); if (cache == null) { log.warn("Could not find configuration [" + name + "]; using defaults."); manager.addCache(name); cache = manager.getCache(name); log.debug("started EHCache region: " + name); } return new EhCache(cache); } catch (net.sf.ehcache.CacheException e) { throw new CacheException(e); } } /** * Returns the next timestamp. */ public long nextTimestamp() { return Timestamper.next(); } /** * Callback to perform any necessary initialization of the underlying cache implementation * during SessionFactory construction. * * @param properties current configuration settings. */ public void start(Properties properties) throws CacheException { if (manager != null) { log.warn("Attempt to restart an already started EhCacheProvider. Use sessionFactory.close() " + " between repeated calls to buildSessionFactory. Using previously created EhCacheProvider." + " If this behaviour is required, consider using net.sf.ehcache.hibernate.SingletonEhCacheProvider."); return; } try { String configurationResourceName = null; if (properties != null) { configurationResourceName = (String) properties.get(Environment.CACHE_PROVIDER_CONFIG); } if (StringHelper.isEmpty(configurationResourceName)) { manager = new CacheManager(); } else { URL url = loadResource(configurationResourceName); manager = new CacheManager(url); } // Register statistics MBean of EHCache on the current MBean server log.info("registering EHCache monitoring MBean"); MBeanServer mBeanServer = ManagementFactory.getPlatformMBeanServer(); ManagementService.registerMBeans(manager, mBeanServer, false, false, false, true); } catch (net.sf.ehcache.CacheException e) { //yukky! Don't you have subclasses for that! //TODO race conditions can happen here if (e.getMessage() .startsWith("Cannot parseConfiguration CacheManager. Attempt to create a new instance of " + "CacheManager using the diskStorePath")) { throw new CacheException( "Attempt to restart an already started EhCacheProvider. Use sessionFactory.close() " + " between repeated calls to buildSessionFactory. Consider using net.sf.ehcache.hibernate.SingletonEhCacheProvider.", e); } else { throw e; } } } private URL loadResource(String configurationResourceName) { URL url = ConfigHelper.locateConfig(configurationResourceName); if (log.isDebugEnabled()) { log.debug("Creating EhCacheProvider from a specified resource: " + configurationResourceName + " Resolved to URL: " + url); } return url; } /** * Callback to perform any necessary cleanup of the underlying cache implementation * during SessionFactory.close(). */ public void stop() { if (manager != null) { manager.shutdown(); manager = null; } } public boolean isMinimalPutsEnabledByDefault() { return false; } }