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.apache.synapse.core.axis2; import java.io.BufferedReader; import java.io.File; import java.io.IOException; import java.io.InputStreamReader; import java.net.URL; import java.net.URLClassLoader; import java.util.LinkedList; import java.util.List; import javax.xml.namespace.QName; import org.apache.axis2.Axis2Constants; import org.apache.axis2.context.ConfigurationContext; import org.apache.axis2.deployment.Deployer; import org.apache.axis2.deployment.DeploymentClassLoader; import org.apache.axis2.deployment.DeploymentException; import org.apache.axis2.deployment.repository.util.DeploymentFileData; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.apache.synapse.config.xml.MediatorFactory; import org.apache.synapse.config.xml.MediatorFactoryFinder; import org.apache.synapse.config.xml.MediatorSerializer; import org.apache.synapse.config.xml.MediatorSerializerFinder; import org.apache.synapse.config.xml.StartupFactory; import org.apache.synapse.config.xml.StartupFinder; /** * This will support the hot deployment and hot update of Synapse extensions (mediators * and startups) at runtime using the Axis2 concepts of deployers. */ public class ExtensionDeployer implements Deployer { /** * Holds the log variable for logging purposes */ private static final Log log = LogFactory.getLog(ExtensionDeployer.class); /** * ConfigurationContext of Axis2 */ private ConfigurationContext cfgCtx = null; /** * Initializes the Deployer * * @param configurationContext - ConfigurationContext of Axis2 from which * the deployer is initialized */ public void init(ConfigurationContext configurationContext) { this.cfgCtx = configurationContext; } /** * This will be called when there is a change in the specified deployment * folder (in the axis2.xml) and this will load the relevant classes to the system and * register them with the MediatorFactoryFinder * * @param deploymentFileData - describes the updated file * @throws DeploymentException - in case an error on the deployment */ public void deploy(DeploymentFileData deploymentFileData) throws DeploymentException { log.info("Loading extensions from: " + deploymentFileData.getAbsolutePath()); // get the context class loader for the later restore of the context class loader ClassLoader prevCl = Thread.currentThread().getContextClassLoader(); try { boolean isDirectory = deploymentFileData.getFile().isDirectory(); deploymentFileData.setClassLoader(isDirectory, getClass().getClassLoader(), (File) cfgCtx .getAxisConfiguration().getParameterValue(Axis2Constants.Configuration.ARTIFACTS_TEMP_DIR)); DeploymentClassLoader urlCl = (DeploymentClassLoader) deploymentFileData.getClassLoader(); Thread.currentThread().setContextClassLoader(urlCl); // StartupFactory registration for (StartupFactory factory : getProviders(StartupFactory.class, urlCl)) { QName tagQName = factory.getTagQName(); Class<? extends StartupFactory> clazz = factory.getClass(); StartupFinder finder = StartupFinder.getInstance(); finder.getFactoryMap().put(tagQName, clazz); finder.getSerializerMap().put(tagQName, factory.getSerializerClass()); log.info("Registered startup factory and serializer for " + tagQName); } // MediatorFactory registration for (MediatorFactory factory : getProviders(MediatorFactory.class, urlCl)) { QName tagQName = factory.getTagQName(); Class<? extends MediatorFactory> clazz = factory.getClass(); MediatorFactoryFinder.getInstance().getFactoryMap().put(tagQName, clazz); log.info("Registered mediator factory " + clazz.getName() + " for " + tagQName); } // MediatorSerializer registration for (MediatorSerializer serializer : getProviders(MediatorSerializer.class, urlCl)) { String mediatorClassName = serializer.getMediatorClassName(); MediatorSerializerFinder.getInstance().getSerializerMap().put(mediatorClassName, serializer); log.info("Registered mediator serializer " + serializer.getClass().getName() + " for " + mediatorClassName); } } catch (IOException e) { handleException("I/O error in reading the mediator jar file", e); } finally { // restore the class loader back if (log.isDebugEnabled()) { log.debug("Restoring the context class loader to the original"); } Thread.currentThread().setContextClassLoader(prevCl); } } private <T> List<T> getProviders(Class<T> providerClass, URLClassLoader loader) throws DeploymentException, IOException { List<T> providers = new LinkedList<T>(); String providerClassName = providerClass.getName(); providerClassName = providerClassName.substring(providerClassName.indexOf('.') + 1); URL servicesURL = loader.findResource("META-INF/services/" + providerClass.getName()); if (servicesURL != null) { BufferedReader in = new BufferedReader(new InputStreamReader(servicesURL.openStream())); try { String className; while ((className = in.readLine()) != null) { log.info("Loading the " + providerClassName + " implementation: " + className); try { Class<? extends T> clazz = loader.loadClass(className).asSubclass(providerClass); providers.add(clazz.newInstance()); } catch (ClassNotFoundException e) { handleException("Unable to find the specified class on the path or " + "in the jar file", e); } catch (IllegalAccessException e) { handleException("Unable to load the class from the jar", e); } catch (InstantiationException e) { handleException("Unable to instantiate the class specified", e); } } } finally { in.close(); } } return providers; } /** * This will not be implemented because we do not support changing the directory at runtime * * @param string - */ public void setDirectory(String string) { // we do not support changing the directory } /** * This will not be implemented because we do not support changing the extension at runtime * * @param string - */ public void setExtension(String string) { // we do not support changing the extension } /** * This will be called when a particular jar file is deleted from the specified folder. * * @param string - filename of the deleted file * @throws DeploymentException - incase of an error in undeployment */ public void unDeploy(String string) throws DeploymentException { // todo: implement the undeployement } private void handleException(String message, Exception e) throws DeploymentException { if (log.isDebugEnabled()) { log.debug(message, e); } throw new DeploymentException(message, e); } }