groupfactory.java

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//
// This file is part of the OpenNMS(R) Application.
//
// OpenNMS(R) is Copyright (C) 2002-2003 The OpenNMS Group, Inc.  All rights reserved.
// OpenNMS(R) is a derivative work, containing both original code, included code and modified
// code that was published under the GNU General Public License. Copyrights for modified 
// and included code are below.
//
// OpenNMS(R) is a registered trademark of The OpenNMS Group, Inc.
//
// Modifications:
//
// 2003 Jan 31: Cleaned up some unused imports.
//
// Original code base Copyright (C) 1999-2001 Oculan Corp.  All rights reserved.
//
// This program 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 2 of the License, or
// (at your option) any later version.
//
// This program 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 this program; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
//       
// For more information contact: 
//      OpenNMS Licensing       <[e-mail]>
//      http://www.opennms.org/
//      http://www.opennms.com/
//
// Tab Size = 8
//

package org.opennms.netmgt.config;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileWriter;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.Reader;

import org.exolab.castor.xml.MarshalException;
import org.exolab.castor.xml.ValidationException;
import org.opennms.netmgt.ConfigFileConstants;

public class GroupFactory extends GroupManager {
    /**
     * The static singleton instance object
     */
    private static GroupFactory s_instance;

    /**
     * Boolean indicating if the init() method has been called
     */
    private static boolean s_initialized = false;

    /**
     * 
     */
    private File m_groupsConfFile;

    /**
     * 
     */
    private long m_lastModified;

    /**
     * Constructor which parses the file
     */
    public GroupFactory() {
    }

    public static synchronized void init() throws IOException, FileNotFoundException, MarshalException, ValidationException {

        if (!s_initialized) {
            getInstance().reload();
            s_initialized = true;
        }
    }

    /**
     * Singleton static call to get the only instance that should exist for the
     * GroupFactory
     * 
     * @return the single group factory instance
     */
    public static synchronized GroupFactory getInstance() {

        if (s_instance == null || !s_initialized) {
            s_instance = new GroupFactory();
        }

        return s_instance;
    }

    /**
     * Parses the groups.xml via the Castor classes
     */
    public synchronized void reload() throws IOException, FileNotFoundException, MarshalException, ValidationException {
        File confFile = ConfigFileConstants.getFile(ConfigFileConstants.GROUPS_CONF_FILE_NAME);

        reloadFromFile(confFile);
    }

    /**
     * @param confFile
     * @throws FileNotFoundException
     * @throws MarshalException
     * @throws ValidationException
     */
    private void reloadFromFile(File confFile) throws FileNotFoundException, MarshalException, ValidationException {
        m_groupsConfFile = confFile;
        InputStream configIn = new FileInputStream(m_groupsConfFile);
        m_lastModified = m_groupsConfFile.lastModified();

        Reader reader = new InputStreamReader(configIn);

        parseXml(reader);
    }

    /**
     * @param data
     * @throws IOException
     */
    protected void saveXml(String data) throws IOException {
        if (data != null) {
            FileWriter fileWriter = new FileWriter(m_groupsConfFile);
            fileWriter.write(data);
            fileWriter.flush();
            fileWriter.close();
        }
    }

    /**
     * 
     */
    protected void updateFromFile() throws IOException, MarshalException, ValidationException {
        if (m_lastModified != m_groupsConfFile.lastModified()) {
            reload();
        }
    }
}