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.FileNotFoundException; import java.io.IOException; import java.io.InputStream; import java.util.HashMap; import java.util.Map; 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.xml.CastorUtils; import org.opennms.netmgt.config.viewsdisplay.View; import org.opennms.netmgt.config.viewsdisplay.Viewinfo; /** * <p>ViewsDisplayFactory class.</p> * * @author ranger * @version $Id: $ */ public class ViewsDisplayFactory { /** The singleton instance. */ private static ViewsDisplayFactory m_instance; /** File path of groups.xml. */ protected File m_viewsDisplayFile; /** Boolean indicating if the init() method has been called. */ protected boolean initialized = false; /** Timestamp of the viewDisplay file, used to know when to reload from disk. */ protected long m_lastModified; /** Map of view objects by name. */ protected Map<String, View> m_viewsMap; private Viewinfo m_viewInfo; /** * Empty private constructor so this class cannot be instantiated outside * itself. * @throws IOException * @throws FileNotFoundException * @throws ValidationException * @throws MarshalException */ private ViewsDisplayFactory() throws MarshalException, ValidationException, FileNotFoundException, IOException { reload(); } /** * <p>Constructor for ViewsDisplayFactory.</p> * * @param file a {@link java.lang.String} object. * @throws org.exolab.castor.xml.MarshalException if any. * @throws org.exolab.castor.xml.ValidationException if any. * @throws java.io.FileNotFoundException if any. * @throws java.io.IOException if any. */ public ViewsDisplayFactory(String file) throws MarshalException, ValidationException, FileNotFoundException, IOException { setViewsDisplayFile(new File(file)); reload(); } /** * Be sure to call this method before calling getInstance(). * * @throws java.io.IOException if any. * @throws java.io.FileNotFoundException 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, FileNotFoundException, MarshalException, ValidationException { if (m_instance == null) { setInstance(new ViewsDisplayFactory()); } } /** * Singleton static call to get the only instance that should exist for the * ViewsDisplayFactory * * @return the single views display factory instance * @throws java.lang.IllegalStateException * if init has not been called */ public static synchronized ViewsDisplayFactory getInstance() { if (m_instance == null) { throw new IllegalStateException("You must call ViewDisplay.init() before calling getInstance()."); } return m_instance; } /** * Parses the viewsdisplay.xml via the Castor classes * * @throws java.io.IOException if any. * @throws java.io.FileNotFoundException if any. * @throws org.exolab.castor.xml.MarshalException if any. * @throws org.exolab.castor.xml.ValidationException if any. */ public synchronized void reload() throws IOException, FileNotFoundException, MarshalException, ValidationException { InputStream stream = null; try { stream = getStream(); unmarshal(stream); } finally { if (stream != null) { IOUtils.closeQuietly(stream); } } } private void unmarshal(InputStream stream) throws MarshalException, ValidationException { m_viewInfo = CastorUtils.unmarshal(Viewinfo.class, stream); updateViewsMap(); } private void updateViewsMap() { Map<String, View> viewsMap = new HashMap<String, View>(); for (View view : m_viewInfo.getViewCollection()) { viewsMap.put(view.getViewName(), view); } m_viewsMap = viewsMap; } private InputStream getStream() throws IOException { File viewsDisplayFile = getViewsDisplayFile(); m_lastModified = viewsDisplayFile.lastModified(); InputStream stream = new FileInputStream(viewsDisplayFile); return stream; } /** * <p>setViewsDisplayFile</p> * * @param viewsDisplayFile a {@link java.io.File} object. */ public void setViewsDisplayFile(File viewsDisplayFile) { m_viewsDisplayFile = viewsDisplayFile; } /** * <p>getViewsDisplayFile</p> * * @return a {@link java.io.File} object. * @throws java.io.IOException if any. */ public File getViewsDisplayFile() throws IOException { if (m_viewsDisplayFile == null) { m_viewsDisplayFile = ConfigFileConstants.getFile(ConfigFileConstants.VIEWS_DISPLAY_CONF_FILE_NAME); } return m_viewsDisplayFile; } /** * Can be null * * @param viewName a {@link java.lang.String} object. * @return a {@link org.opennms.netmgt.config.viewsdisplay.View} object. * @throws java.io.IOException if any. * @throws org.exolab.castor.xml.MarshalException if any. * @throws org.exolab.castor.xml.ValidationException if any. */ public View getView(String viewName) throws IOException, MarshalException, ValidationException { if (viewName == null) { throw new IllegalArgumentException("Cannot take null parameters."); } updateFromFile(); View view = m_viewsMap.get(viewName); return view; } /** * <p>getDefaultView</p> * * @return a {@link org.opennms.netmgt.config.viewsdisplay.View} object. */ public View getDefaultView() { return m_viewsMap.get(m_viewInfo.getDefaultView()); } /** * Reload the viewsdisplay.xml file if it has been changed since we last * read it. * * @throws java.io.IOException if any. * @throws org.exolab.castor.xml.MarshalException if any. * @throws org.exolab.castor.xml.ValidationException if any. */ protected void updateFromFile() throws IOException, MarshalException, ValidationException { if (m_lastModified != m_viewsDisplayFile.lastModified()) { reload(); } } /** * <p>setInstance</p> * * @param instance a {@link org.opennms.netmgt.config.ViewsDisplayFactory} object. */ public static void setInstance(ViewsDisplayFactory instance) { m_instance = instance; m_instance.initialized = true; } /** * <p>getDisconnectTimeout</p> * * @return a int. */ public int getDisconnectTimeout() { return m_viewInfo.getDisconnectTimeout(); } }