Java tutorial
/******************************************************************************* * This file is part of OpenNMS(R). * * Copyright (C) 2012 The OpenNMS Group, Inc. * OpenNMS(R) is Copyright (C) 1999-2012 The OpenNMS Group, Inc. * * OpenNMS(R) is a registered trademark of The OpenNMS Group, Inc. * * OpenNMS(R) is free software: you can redistribute it and/or modify * it under the terms of the GNU General Public License as published * by the Free Software Foundation, either version 3 of the License, * or (at your option) any later version. * * OpenNMS(R) is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with OpenNMS(R). If not, see: * http://www.gnu.org/licenses/ * * For more information contact: * OpenNMS(R) Licensing <license@opennms.org> * http://www.opennms.org/ * http://www.opennms.com/ *******************************************************************************/ package org.opennms.ng.services.capsdconfig; import java.io.File; import java.io.IOException; import org.exolab.castor.xml.MarshalException; import org.exolab.castor.xml.ValidationException; import org.opennms.core.utils.ConfigFileConstants; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import org.springframework.util.Assert; /** * This is the singleton class used to load the configuration for the OpenNMS * Capsd service from the capsd-configuration xml file. * * <strong>Note: </strong>Users of this class should make sure the * <em>init()</em> is called before calling any other method to ensure the * config is loaded before accessing other convenience methods. * * @author <a href="mailto:mike@opennms.org">Mike Davidson </a> * @author <a href="http://www.opennms.org/">OpenNMS </a> * @author <a href="mailto:mike@opennms.org">Mike Davidson </a> * @author <a href="http://www.opennms.org/">OpenNMS </a> * @version $Id: $ */ public class CapsdConfigFactory { private static final Logger LOG = LoggerFactory.getLogger(CapsdConfigFactory.class); /** * The singleton instance of this factory */ private static CapsdConfig s_singleton = null; /** * This class only has static methods. */ public CapsdConfigFactory() { } /** * Load the config from the default config file and create the singleton * instance of this factory. * * @exception java.io.IOException * Thrown if the specified config file cannot be read * @exception org.exolab.castor.xml.MarshalException * Thrown if the file does not conform to the schema. * @exception org.exolab.castor.xml.ValidationException * Thrown if the contents do not match the required schema. * @throws java.io.IOException if any. * @throws org.exolab.castor.xml.MarshalException if any. * @throws org.exolab.castor.xml.ValidationException if any. */ public static synchronized void init() throws IOException, MarshalException, ValidationException { if (isLoaded()) { /* * init already called - return * to reload, reload() will need to be called */ return; } File cfgFile = ConfigFileConstants.getFile(ConfigFileConstants.CAPSD_CONFIG_FILE_NAME); LOG.debug("init: config file path: {}", cfgFile.getPath()); DefaultCapsdConfigManager capsdConfig = new DefaultCapsdConfigManager(); capsdConfig.update(); setInstance(capsdConfig); } private static boolean isLoaded() { return s_singleton != null; } /** * Reload the config from the default config file * * @exception java.io.IOException * Thrown if the specified config file cannot be read/loaded * @exception org.exolab.castor.xml.MarshalException * Thrown if the file does not conform to the schema. * @exception org.exolab.castor.xml.ValidationException * Thrown if the contents do not match the required schema. * @throws java.io.IOException if any. * @throws org.exolab.castor.xml.MarshalException if any. * @throws org.exolab.castor.xml.ValidationException if any. */ public static synchronized void reload() throws IOException, MarshalException, ValidationException { s_singleton = null; init(); } /** * Return the singleton instance of this factory. * * @return The current factory instance. * @throws IllegalStateException * Thrown if the factory has not yet been initialized. */ public static synchronized CapsdConfig getInstance() { Assert.state(isLoaded(), "The factory has not been initialized"); return s_singleton; } public CapsdConfig getConf() { return s_singleton; } /** * <p>setInstance</p> * * @param instance a {@link CapsdConfig} object. */ public static synchronized void setInstance(CapsdConfig instance) { s_singleton = instance; } }