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 com.netxforge.oss2.config; import java.io.File; import java.io.FileInputStream; import java.io.FileOutputStream; import java.io.IOException; import java.io.InputStream; import java.io.OutputStreamWriter; import java.io.Writer; import org.apache.commons.io.IOUtils; import org.exolab.castor.xml.MarshalException; import org.exolab.castor.xml.ValidationException; import org.opennms.core.utils.ConfigFileConstants; import org.opennms.core.utils.ThreadCategory; /** * This is the singleton class used to load the configuration for the OpenNMS * Poller service from the poller-configuration XML file. * * A mapping of the configured URLs to the IP list they contain is built at * init() time so as to avoid numerous file reads. * * <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:jamesz@opennms.com">James Zuo </a> * @author <a href="mailto:mike@opennms.org">Mike Davidson </a> * @author <a href="mailto:sowmya@opennms.org">Sowmya Nataraj </a> * @author <a href="http://www.opennms.org/">OpenNMS </a> * @author <a href="mailto:jamesz@opennms.com">James Zuo </a> * @author <a href="mailto:mike@opennms.org">Mike Davidson </a> * @author <a href="mailto:sowmya@opennms.org">Sowmya Nataraj </a> * @author <a href="http://www.opennms.org/">OpenNMS </a> * @author <a href="mailto:jamesz@opennms.com">James Zuo </a> * @author <a href="mailto:mike@opennms.org">Mike Davidson </a> * @author <a href="mailto:sowmya@opennms.org">Sowmya Nataraj </a> * @author <a href="http://www.opennms.org/">OpenNMS </a> * @author <a href="mailto:jamesz@opennms.com">James Zuo </a> * @author <a href="mailto:mike@opennms.org">Mike Davidson </a> * @author <a href="mailto:sowmya@opennms.org">Sowmya Nataraj </a> * @author <a href="http://www.opennms.org/">OpenNMS </a> * @version $Id: $ */ public final class SnmpInterfacePollerConfigFactory extends SnmpInterfacePollerConfigManager { /** * The singleton instance of this factory */ private static SnmpInterfacePollerConfig m_singleton = null; /** * This member is set to true if the configuration file has been loaded. */ private static boolean m_loaded = false; /** * Loaded version */ private long m_currentVersion = -1L; /** * <p>Constructor for SnmpInterfacePollerConfigFactory.</p> * * @param currentVersion a long. * @param stream a {@link java.io.InputStream} object. * @param localServer a {@link java.lang.String} object. * @param verifyServer a boolean. * @throws org.exolab.castor.xml.MarshalException if any. * @throws org.exolab.castor.xml.ValidationException if any. * @throws java.io.IOException if any. */ public SnmpInterfacePollerConfigFactory(long currentVersion, InputStream stream, String localServer, boolean verifyServer) throws MarshalException, ValidationException, IOException { super(stream, localServer, verifyServer); m_currentVersion = currentVersion; } /** * 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 (m_loaded) { // init already called - return // to reload, reload() will need to be called return; } OpennmsServerConfigFactory.init(); OpennmsServerConfigFactory onmsSvrConfig = OpennmsServerConfigFactory.getInstance(); File cfgFile = ConfigFileConstants.getFile(ConfigFileConstants.SNMP_INTERFACE_POLLER_CONFIG_FILE_NAME); logStatic().debug("init: config file path: " + cfgFile.getPath()); InputStream stream = null; try { stream = new FileInputStream(cfgFile); SnmpInterfacePollerConfigFactory config = new SnmpInterfacePollerConfigFactory(cfgFile.lastModified(), stream, onmsSvrConfig.getServerName(), onmsSvrConfig.verifyServer()); setInstance(config); } finally { if (stream != null) { IOUtils.closeQuietly(stream); } } } private static ThreadCategory logStatic() { return ThreadCategory.getInstance(SnmpInterfacePollerConfigFactory.class); } /** * 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 { init(); getInstance().update(); } /** {@inheritDoc} */ protected synchronized void saveXml(String xml) throws IOException { if (xml != null) { long timestamp = System.currentTimeMillis(); File cfgFile = ConfigFileConstants.getFile(ConfigFileConstants.SNMP_INTERFACE_POLLER_CONFIG_FILE_NAME); logStatic().debug("saveXml: saving config file at " + timestamp + ": " + cfgFile.getPath()); Writer fileWriter = new OutputStreamWriter(new FileOutputStream(cfgFile), "UTF-8"); fileWriter.write(xml); fileWriter.flush(); fileWriter.close(); logStatic().debug("saveXml: finished saving config file: " + cfgFile.getPath()); } } /** * Return the singleton instance of this factory. * * @return The current factory instance. * @throws java.lang.IllegalStateException * Thrown if the factory has not yet been initialized. */ public static synchronized SnmpInterfacePollerConfig getInstance() { if (!m_loaded) { throw new IllegalStateException("The factory has not been initialized"); } return m_singleton; } /** * <p>setInstance</p> * * @param instance a {@link org.opennms.netmgt.config.SnmpInterfacePollerConfig} object. */ public static synchronized void setInstance(SnmpInterfacePollerConfig instance) { m_singleton = instance; m_loaded = true; } /** * <p>update</p> * * @throws java.io.IOException if any. * @throws org.exolab.castor.xml.MarshalException if any. * @throws org.exolab.castor.xml.ValidationException if any. */ public synchronized void update() throws IOException, MarshalException, ValidationException { File cfgFile = ConfigFileConstants.getFile(ConfigFileConstants.SNMP_INTERFACE_POLLER_CONFIG_FILE_NAME); if (cfgFile.lastModified() > m_currentVersion) { m_currentVersion = cfgFile.lastModified(); logStatic().debug("init: config file path: " + cfgFile.getPath()); InputStream stream = null; try { stream = new FileInputStream(cfgFile); reloadXML(stream); } finally { if (stream != null) { IOUtils.closeQuietly(stream); } } logStatic().debug("init: finished loading config file: " + cfgFile.getPath()); } } }