ImmediateProperties.java Source code

Introduction

Here is the source code for ImmediateProperties.java

Source

/*
 * | $Id$
 * |*-------------------------------------------------------------------------*|
 * | Copyright (C) 2009 Virginia Tech | | This file is part of CloudSpace. | |
 * CloudSpace 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. | | CloudSpace 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 CloudSpace; if not, see
 * <http://www.gnu.org/licenses/>.
 */

//package cloudspace.util;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.Properties;

//import org.apache.log4j.Logger;

// -------------------------------------------------------------------------
/**
 * A subclass of the java.util.Properties class that must be initialized from a
 * file on disk, and which always keeps the in-memory property set in sync with
 * the contents on disk.
 * 
 * @author Tony Allevato
 * @author Last changed by $Author$
 * @version $Revision$, $Date$
 */
public class ImmediateProperties extends Properties {
    // ~ Constructors ..........................................................

    // ----------------------------------------------------------
    /**
     * Initializes a new instance of ImmediateProperties by loading them from
     * the specified file.
     * 
     * @param file
     *            the path to the file that backs this Properties instance.
     */
    public ImmediateProperties(File file) {
        super();

        this.backingFile = file;

        FileInputStream stream = null;

        try {
            stream = new FileInputStream(backingFile);
            load(stream);
        } catch (FileNotFoundException e) {
            // Do nothing; start the property set empty if the file did not
            // exist.
        } catch (IOException e) {
            // log.error( "An I/O exception occurred when loading the properties "
            //      + "file at " + backingFile, e );
        } finally {
            try {
                if (stream != null) {
                    stream.close();
                }
            } catch (IOException e) {
                //    log.error( "An I/O exception occurred when trying to close the "
                //        + "stream",
                //        e );
            }
        }
    }

    // ~ Methods ...............................................................

    // ----------------------------------------------------------
    /**
     * Removes the specified property from the file.
     * 
     * @param key
     *            the name of the property to remove
     * @return the previous value of the property
     */
    @Override
    public Object remove(Object key) {
        Object previousValue = super.remove(key);
        writeToFile();
        return previousValue;
    }

    // ----------------------------------------------------------
    /**
     * Sets the value of the specified property.
     * 
     * @param key
     *            the name of the property to set
     * @param value
     *            the value of the property
     * @return the previous value of the property
     */
    @Override
    public Object put(Object key, Object value) {
        Object previousValue = super.put(key, value);
        writeToFile();
        return previousValue;
    }

    // ----------------------------------------------------------
    /**
     * Saves the current properties set to their associated file.
     */
    private void writeToFile() {
        FileOutputStream stream = null;

        try {
            stream = new FileOutputStream(backingFile);
            store(stream, null);
        } catch (IOException e) {
            //   log.error( "An I/O exception occurred when saving the properties",
            //      e );
        } finally {
            try {
                if (stream != null) {
                    stream.close();
                }
            } catch (IOException e) {
                //     log.error( "An I/O exception occurred when closing the stream",
                //         e );
            }
        }
    }

    // ~ Instance/static variables .............................................

    /** The path to the file that backs this Properties instance. */
    private File backingFile;

    private static final long serialVersionUID = -6139105936918525923L;

    // private static final Logger log = Logger.getLogger( ImmediateProperties.class );
}