Java tutorial
/* * Copyright 2002-2008 the original author or authors. * * 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. */ package fr.xebia.management; import java.lang.reflect.Field; import java.lang.reflect.InvocationHandler; import java.lang.reflect.InvocationTargetException; import java.lang.reflect.Method; import java.lang.reflect.Proxy; import java.util.Arrays; import java.util.HashMap; import java.util.Hashtable; import java.util.Map; import javax.management.MBeanServer; import javax.management.MalformedObjectNameException; import javax.management.ObjectName; import javax.servlet.ServletContext; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import org.springframework.beans.factory.FactoryBean; import org.springframework.beans.factory.InitializingBean; import org.springframework.jmx.support.JmxUtils; import org.springframework.util.Assert; import org.springframework.util.ClassUtils; import org.springframework.web.context.ServletContextAware; /** * <p> * Instantiate {@link MBeanServer} which add a "path" property with value * {@link ServletContext#getContextPath()} to each {@link ObjectName} passed as * method parameter. The goal is to prevent collisions between MBeans declared * in different web applications. * </p> * <p> * On Tomcat, an extra property named <code>"host"</code> with the name of the * Tomcat host in which the webapp is declared is added (value * <code>"org.apache.catalina.core.ApplicationContextFacade#context#context#hostName"</code> * ). * </p> * <p> * Sample : EHCache's {@link net.sf.ehcache.management.ManagementService} will * register Hibernate's {@linkplain org.hibernate.cache.StandardQueryCache} as * <code>"net.sf.ehcache:CacheManager=my-cachemanager,name=org.hibernate.cache.StandardQueryCache,type=CacheStatistics"</code> * that could collide with other applications and this MBeanServer will add the * <code>"path"</code> attribute to prevent problems : * <code>"net.sf.ehcache:CacheManager=my-cachemanager,name=org.hibernate.cache.StandardQueryCache, * type=CacheStatistics,path=/my-application</code> " . * </p> * <p> * Implementation decisions: * </p> * <ul> * <li>The added property was named <code>"path"</code> to follow Tomcat JMX * beans naming convention,</li> * <li>This {@link FactoryBean} doesn't extend * {@link org.springframework.beans.factory.config.AbstractFactoryBean} due to * <a href="http://jira.springframework.org/browse/SPR-4968">SPR-4968 : Error * "Singleton instance not initialized yet" triggered by toString call in case * of circular references</a></li> * </ul> * <hr/> * <p> * <strong>Configuration sample:</strong> * </p> * * <pre> * <code> * <beans ... > * <context:mbean-server id="rawMbeanServer" /> * <bean id="mbeanServer" class="fr.xebia.management.ServletContextAwareMBeanServerFactory"> * <property name="mbeanServer" ref="rawMbeanServer" /> * </bean> * <context:mbean-export server="mbeanServer" /> * ... * </beans> * </code> * </pre> * * <p> * An object name * <code>"net.sf.ehcache:CacheManager=my-cache-manager,name=my-cache,type=Cache</code> * " will be registered as * <code>"net.sf.ehcache:CacheManager=my-cache-manager,name=my-cache,type=Cache,host=localhost,path=/my-application"</code> * for an application "my-application" declared in the "localhost" host of a * Tomcat server: attributes <code>"path=/my-application"</code> and * <code>"host=localhost"</code> are added to the object name. * </p> * <p> * <strong>Advanced configuration sample:</strong> * </p> * <p> * The <code>"objectNameExtraAttributes"</code> property allows to manually add * extra attributes in addition to the <code>"path"</code> (and * <code>"host"</code>) attribute that is automatically added. * </p> * * <pre> * <code> * <beans ... > * <context:mbean-server id="rawMbeanServer" /> * <bean id="mbeanServer" class="fr.xebia.management.ServletContextAwareMBeanServerFactory"> * <property name="mbeanServer" ref="rawMbeanServer" /> * <property name="objectNameExtraAttributes" > * <map> * <entry key="ze-app-id-asked-by-ze-monitoring-team" value="my-application-id" /> * </map> * </property> * </bean> * <context:mbean-export server="mbeanServer" /> * ... * </beans> * </code> * </pre> * * <p> * An object name * <code>"net.sf.ehcache:CacheManager=my-cache-manager,name=my-cache,type=Cache"</code> * will be registered as * <code>"net.sf.ehcache:CacheManager=my-cache-manager,ze-app-id-asked-by-ze-monitoring-team=my-application-id, * name=my-cache,type=Cache,host=localhost,path=/my-application"</code> * for an application "my-application" declared in the "localhost" host of a * Tomcat server: attributes <code>"path=/my-application"</code>, * <code>"host=localhost"</code>and * <code>"ze-app-id-asked-by-ze-monitoring-team=my-application-id"</code> are * added to the object name. * </p> * * @author <a href="mailto:cyrille@cyrilleleclerc.com">Cyrille Le Clerc</a> */ public class ServletContextAwareMBeanServerFactory implements FactoryBean<MBeanServer>, ServletContextAware, InitializingBean { protected MBeanServer instance; protected final Logger logger = LoggerFactory.getLogger(ServletContextAwareMBeanServerFactory.class); protected Map<String, String> objectNameExtraAttributes = new HashMap<String, String>(); protected MBeanServer server; protected ServletContext servletContext; public void afterPropertiesSet() throws Exception { if (this.server == null) { this.server = JmxUtils.locateMBeanServer(); } Assert.notNull(this.servletContext, "servletContext can NOT be null"); objectNameExtraAttributes.put("path", servletContext.getContextPath()); if ("org.apache.catalina.core.ApplicationContextFacade".equals(servletContext.getClass().getName())) { Field applicationContextFacadeContextField = Class .forName("org.apache.catalina.core.ApplicationContextFacade").getDeclaredField("context"); applicationContextFacadeContextField.setAccessible(true); Field applicationContextContextField = Class.forName("org.apache.catalina.core.ApplicationContext") .getDeclaredField("context"); applicationContextContextField.setAccessible(true); Field standardContextHostNameField = Class.forName("org.apache.catalina.core.StandardContext") .getDeclaredField("hostName"); standardContextHostNameField.setAccessible(true); Object applicationContext = applicationContextFacadeContextField.get(servletContext); Object standardContext = applicationContextContextField.get(applicationContext); String hostName = (String) standardContextHostNameField.get(standardContext); objectNameExtraAttributes.put("host", hostName); } logger.trace("Extra objectname attributes : {}" + this.objectNameExtraAttributes); } public MBeanServer getObject() throws Exception { if (instance == null) { InvocationHandler invocationHandler = new InvocationHandler() { /** * <p> * Copy the given <code>objectName</code> adding the extra * attributes. * </p> */ protected ObjectName addExtraAttributesToObjectName(ObjectName objectName) throws MalformedObjectNameException { Hashtable<String, String> table = new Hashtable<String, String>( objectName.getKeyPropertyList()); table.putAll(objectNameExtraAttributes); ObjectName result = ObjectName.getInstance(objectName.getDomain(), table); logger.trace("addExtraAttributesToObjectName({}): {}", objectName, result); return result; } public Object invoke(Object proxy, Method method, Object[] args) throws Throwable { Object[] modifiedArgs = args.clone(); for (int i = 0; i < modifiedArgs.length; i++) { Object arg = modifiedArgs[i]; if (arg instanceof ObjectName) { ObjectName objectName = (ObjectName) arg; modifiedArgs[i] = addExtraAttributesToObjectName(objectName); } } if (logger.isDebugEnabled()) { logger.debug(method + " : " + Arrays.asList(modifiedArgs)); } try { return method.invoke(server, modifiedArgs); } catch (InvocationTargetException ite) { throw ite.getCause(); } } }; instance = (MBeanServer) Proxy.newProxyInstance(ClassUtils.getDefaultClassLoader(), new Class[] { MBeanServer.class }, invocationHandler); } return instance; } public Class<? extends MBeanServer> getObjectType() { return MBeanServer.class; } public boolean isSingleton() { return true; } /** * Deprecated to match * {@link org.springframework.jmx.export.MBeanExporter#setServer(MBeanServer)} * . * * @deprecated Use {@link #setServer(MBeanServer)}. */ @Deprecated public void setMbeanServer(MBeanServer mbeanServer) { this.server = mbeanServer; } public void setObjectNameExtraAttributes(Map<String, String> objectNameExtraAttributes) { this.objectNameExtraAttributes = objectNameExtraAttributes; } public void setServer(MBeanServer server) { this.server = server; } public void setServletContext(ServletContext servletContext) { this.servletContext = servletContext; } }