Java tutorial
/** * $Id$ * $URL$ * BeanCollectorAutoRegistrar.java - entity-broker - Apr 15, 2008 4:29:18 PM - azeckoski ************************************************************************** * Copyright (c) 2007, 2008, 2009 The Sakai Foundation * * Licensed under the Educational Community 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.opensource.org/licenses/ECL-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.sakaiproject.entitybroker.util.spring; import java.io.Serializable; import java.util.ArrayList; import java.util.Collections; import java.util.Comparator; import java.util.HashMap; import java.util.HashSet; import java.util.List; import java.util.Map; import java.util.Set; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.sakaiproject.entitybroker.collector.AutoRegister; import org.sakaiproject.entitybroker.collector.BeanCollector; import org.sakaiproject.entitybroker.collector.OrderedBean; import org.sakaiproject.entitybroker.collector.BeanMapCollector; import org.springframework.beans.factory.InitializingBean; import org.springframework.beans.factory.config.BeanPostProcessor; import org.springframework.beans.factory.config.ConfigurableBeanFactory; import org.springframework.context.ApplicationContext; import org.springframework.context.ApplicationContextAware; import org.springframework.context.ApplicationEvent; import org.springframework.context.ApplicationListener; import org.springframework.context.ConfigurableApplicationContext; /** * This will collect the autoregistered beans and place them into all the locations which requested them * * @author Aaron Zeckoski (aaron@caret.cam.ac.uk) */ public class BeanCollectorAutoRegistrar implements ApplicationListener, ApplicationContextAware, InitializingBean { private static Log log = LogFactory.getLog(BeanCollectorAutoRegistrar.class); private ApplicationContext applicationContext; public void setApplicationContext(ApplicationContext applicationContext) { this.applicationContext = applicationContext; } public void onApplicationEvent(ApplicationEvent event) { // We do not actually respond to any events, purpose is to time initialisation only. } private Set<String> autoRegistered; public void init() { String[] autobeans = applicationContext.getBeanNamesForType(AutoRegister.class, false, false); autoRegistered = new HashSet<String>(); for (int i = 0; i < autobeans.length; i++) { autoRegistered.add(autobeans[i]); } } public void afterPropertiesSet() throws Exception { log.debug("setAC: " + applicationContext.getDisplayName()); ConfigurableApplicationContext cac = (ConfigurableApplicationContext) applicationContext; ConfigurableBeanFactory cbf = (ConfigurableBeanFactory) cac.getBeanFactory(); cbf.addBeanPostProcessor(new BeanPostProcessor() { @SuppressWarnings("unchecked") public Object postProcessBeforeInitialization(Object bean, String beanName) { if (bean instanceof BeanCollector<?>) { BeanCollector<Object> bc = (BeanCollector<Object>) bean; Class<?> c = bc.getCollectedType(); if (c == null) { throw new IllegalArgumentException("collected type cannot be null"); } List<Object> l = getAutoRegisteredBeansOfType(c); logCollectedBeanInsertion(beanName, c.getName(), l); bc.setCollectedBeans(l); } else if (bean instanceof BeanMapCollector) { BeanMapCollector bc = (BeanMapCollector) bean; Class<?>[] cArray = bc.getCollectedTypes(); if (cArray == null) { throw new IllegalArgumentException("collected types cannot be null"); } Map<Class<?>, List<?>> collectedBeans = new HashMap<Class<?>, List<?>>(); for (int i = 0; i < cArray.length; i++) { List<Object> l = getAutoRegisteredBeansOfType(cArray[i]); logCollectedBeanInsertion(beanName, cArray[i].getName(), l); collectedBeans.put(cArray[i], l); } bc.setCollectedBeansMap(collectedBeans); } return bean; } public Object postProcessAfterInitialization(Object bean, String beanName) { return bean; } }); } /** * Get all autoregistered beans of a specific type * @param c the class type * @return a list of the matching beans */ private List<Object> getAutoRegisteredBeansOfType(Class<?> c) { String[] autobeans = applicationContext.getBeanNamesForType(c, false, false); List<Object> l = new ArrayList<Object>(); for (String autobean : autobeans) { if (autoRegistered.contains(autobean)) { Object bean = applicationContext.getBean(autobean); l.add(bean); } } Collections.sort(l, new OrderComparator()); return l; } /** * Generate a log message about the collected insertion * @param beanName the name of the bean getting collected beans inserted into it * @param l the list of beans that were inserted */ private void logCollectedBeanInsertion(String beanName, String beanType, List<Object> l) { StringBuilder registeredBeans = new StringBuilder(); registeredBeans.append("["); for (int i = 0; i < l.size(); i++) { if (i > 0) { registeredBeans.append(","); } registeredBeans.append(l.get(i).getClass().getName()); } registeredBeans.append("]"); log.info("Set collected beans of type (" + beanType + ") on bean (" + beanName + ") to (" + l.size() + ") " + registeredBeans.toString()); } /** * Comparator to order the collected beans based on order or use default order otherwise * * @author Aaron Zeckoski (aaron@caret.cam.ac.uk) */ public static class OrderComparator implements Comparator<Object>, Serializable { public final static long serialVersionUID = 1l; public int compare(Object arg0, Object arg1) { if (arg0 instanceof OrderedBean && arg1 instanceof OrderedBean) { return ((OrderedBean) arg0).getOrder() - ((OrderedBean) arg1).getOrder(); } else if (arg0 instanceof OrderedBean) { return -1; } else if (arg1 instanceof OrderedBean) { return 1; } else { return 0; } } } }