propertyloader.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.
//
// 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/
//

package org.opennms.web.parsers;

import java.io.FileInputStream;
import java.io.IOException;
import java.util.Iterator;
import java.util.Properties;

/**
 * This class allows another class to load the appropriate property files into
 * one complete Property object. It enables the loading of a single specific
 * property file, a specific property file and the bluebird properties, or the
 * previous two along with the System properties where the System properties
 * take precedence over the previous two.
 * 
 * @author <A HREF="mailto:[e-mail]">Jason Johns </A>
 * @author <A HREF="http://www.opennms.org/">OpenNMS </A>
 * 
 * @version 1.1.1.1
 */
public class PropertyLoader {
    /**
     * The bluebird system property file name
     */
    public static final String BLUEBIRD_PROP = "etc/bluebird";

    /**
     * Only a local property file will be loaded
     */
    public static final int LOCAL_ONLY = 1 << 0;

    /**
     * A local property and the bluebird properties will be loaded into the same
     * Properties object.
     */
    public static final int LOCAL_BLUEBIRD = 1 << 1;

    /**
     * Loads a local property file, the bluebird properties, and the system
     * properties into the same Properties object. The system properties will
     * not be overwritten, so if a property was set on the command line that
     * will take precedece.
     */
    public static final int ALL = 1 << 2;

    /**
     * This method decides which option the user wants and loads the files
     * according to the decision.
     * 
     * @param aFileName
     *            the name of a specific property file to load
     * @param loadMask
     *            an integer describing which load option to use
     * @return the properties of the option
     */
    public static Properties load(String aFileName, int loadMask) {
        Properties properties = null;

        if ((loadMask & LOCAL_ONLY) == LOCAL_ONLY) {
            properties = loadLocal(aFileName);
        }

        if ((loadMask & LOCAL_BLUEBIRD) == LOCAL_BLUEBIRD) {
            properties = loadLocal(BLUEBIRD_PROP, loadLocal(aFileName));
        }

        if ((loadMask & ALL) == ALL) {
            properties = loadSystem(loadLocal(BLUEBIRD_PROP, loadLocal(aFileName)));
        }

        return properties;
    }

    /**
     * This method loads a single specific property file.
     * 
     * @param aFileName
     *            name of the property file to load
     * @return the loaded properties
     */
    public static Properties loadLocal(String aFileName) {
        Properties properties = null;

        FileInputStream pfile = null;
        try {
            properties = new Properties();
            pfile = new FileInputStream(aFileName);
            properties.load(pfile);
            pfile.close();
        } catch (IOException e) {
            // do nothing
        }

        return properties;
    }

    /**
     * This method loads a specific property file in combination with some
     * existing properties. The specific properties will take precedence over
     * the existing properties.
     * 
     * @param aFileName
     *            name of the property file to load
     * @param someProperties
     *            the existing properties
     * @return the loaded properties
     */
    public static Properties loadLocal(String aFileName, Properties someProperties) {
        Properties properties = null;

        FileInputStream pfile = null;
        try {
            properties = new Properties(someProperties);
            pfile = new FileInputStream(aFileName);
            properties.load(pfile);
            pfile.close();
        } catch (IOException e) {
            // do nothing
        }

        return properties;
    }

    /**
     * This method loads the System properties into an already existing
     * Properties object. The System properties will overwrite any duplicate
     * properties that already exist.
     * 
     * @param someProperties
     *            the existing properties
     * @return the loaded properties
     */
    public static Properties loadSystem(Properties someProperties) {
        //	
        // iterate over keys in system map
        // and overwrite any in current properties.
        //
        Iterator i = System.getProperties().keySet().iterator();
        String key = null;

        while (i.hasNext()) {
            key = (String) i.next();
            someProperties.setProperty(key, System.getProperty(key));
        }

        return someProperties;
    }
}