    001    //$HeadURL: https://svn.wald.intevation.org/svn/deegree/base/branches/2.4_testing/src/org/deegree/io/util/FileMonitor.java $
    002    /*----------------------------------------------------------------------------
    003     This file is part of deegree, http://deegree.org/
    004     Copyright (C) 2001-2009 by:
    005       Department of Geography, University of Bonn
    006     and
    007       lat/lon GmbH
    008
    009     This library is free software; you can redistribute it and/or modify it under
    010     the terms of the GNU Lesser General Public License as published by the Free
    011     Software Foundation; either version 2.1 of the License, or (at your option)
    012     any later version.
    013     This library is distributed in the hope that it will be useful, but WITHOUT
    014     ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
    015     FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
    016     details.
    017     You should have received a copy of the GNU Lesser General Public License
    018     along with this library; if not, write to the Free Software Foundation, Inc.,
    019     59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
    020
    021     Contact information:
    022
    023     lat/lon GmbH
    024     Aennchenstr. 19, 53177 Bonn
    025     Germany
    026     http://lat-lon.de/
    027
    028     Department of Geography, University of Bonn
    029     Prof. Dr. Klaus Greve
    030     Postfach 1147, 53001 Bonn
    031     Germany
    032     http://www.geographie.uni-bonn.de/deegree/
    033
    034     e-mail: info@deegree.org
    035    ----------------------------------------------------------------------------*/
    036
    037    package org.deegree.io.util;
    038
    039    import java.io.File;
    040    import java.io.FileNotFoundException;
    041    import java.net.URL;
    042    import java.util.Hashtable;
    043    import java.util.Timer;
    044    import java.util.TimerTask;
    045
    046    /**
    047     * Replaces inner class Reloader in AbstractOGCServlet.
    048     *
    049     * @author <a href="mailto:tfr@users.sourceforge.net">Torsten Friebe </A>
    050     * @author last edited by: $Author: mschneider $
    051     *
    052     * @version 2.0, $Revision: 18195 $, $Date: 2009-06-18 17:55:39 +0200 (Do, 18. Jun 2009) $
    053     *
    054     * @see org.deegree.enterprise.AbstractOGCServlet
    055     * @see java.io.File#lastModified
    056     * @see <a href="http://www.javaworld.com/javaworld/javatips/jw-javatip125.html">Java Tip 125 </a>
    057     *
    058     * @since 2.0
    059     */
    060
    061    public class FileMonitor {
    062
    063        private static final FileMonitor instance = new FileMonitor();
    064
    065        private Timer timer;
    066
    067        private Hashtable<String, FileMonitorTask> timerEntries;
    068
    069        /**
    070         * Factory method to get singleton instance.
    071         *
    072         * @return the instance
    073         *
    074         */
    075        public static FileMonitor getInstance() {
    076            return instance;
    077        }
    078
    079        protected FileMonitor() {
    080            // Create timer, run timer thread as daemon.
    081            timer = new Timer( true );
    082            timerEntries = new Hashtable<String, FileMonitorTask>();
    083        }
    084
    085        /**
    086         * Add a monitored file with a FileChangeListener.
    087         *
    088         * @param listener
    089         *            listener to notify when the file changed.
    090         * @param fileName
    091         *            name of the file to monitor.
    092         * @param period
    093         *            polling period in milliseconds.
    094         * @throws FileNotFoundException
    095         */
    096        public void addFileChangeListener( FileChangeListener listener, String fileName, long period )
    097                                throws FileNotFoundException {
    098            removeFileChangeListener( listener, fileName );
    099            FileMonitorTask task = new FileMonitorTask( listener, fileName );
    100            timerEntries.put( fileName + listener.hashCode(), task );
    101            timer.schedule( task, period, period );
    102        }
    103
    104        /**
    105         * Remove the listener from the notification list.
    106         *
    107         * @param listener
    108         *            the listener to be removed.
    109         * @param fileName
    110         */
    111        public void removeFileChangeListener( FileChangeListener listener, String fileName ) {
    112            FileMonitorTask task = timerEntries.remove( fileName + listener.hashCode() );
    113            if ( task != null ) {
    114                task.cancel();
    115            }
    116        }
    117
    118        protected void fireFileChangeEvent( FileChangeListener listener, String fileName ) {
    119            listener.fileChanged( fileName );
    120        }
    121
    122        class FileMonitorTask extends TimerTask {
    123
    124            FileChangeListener listener;
    125
    126            String fileName;
    127
    128            File monitoredFile;
    129
    130            long lastModified;
    131
    132            /**
    133             * @param listener
    134             * @param fileName
    135             * @throws FileNotFoundException
    136             */
    137            public FileMonitorTask( FileChangeListener listener, String fileName ) throws FileNotFoundException {
    138                this.listener = listener;
    139                this.fileName = fileName;
    140                this.lastModified = 0;
    141
    142                monitoredFile = new File( fileName );
    143                if ( !monitoredFile.exists() ) { // but is it on CLASSPATH?
    144                    URL fileURL = listener.getClass().getClassLoader().getResource( fileName );
    145                    if ( fileURL != null ) {
    146                        monitoredFile = new File( fileURL.getFile() );
    147                    } else {
    148                        throw new FileNotFoundException( "File Not Found: " + fileName );
    149                    }
    150                }
    151                this.lastModified = monitoredFile.lastModified();
    152            }
    153
    154            @Override
    155            public void run() {
    156                long lastModified = monitoredFile.lastModified();
    157                if ( lastModified != this.lastModified ) {
    158                    this.lastModified = lastModified;
    159                    fireFileChangeEvent( this.listener, this.fileName );
    160                }
    161            }
    162        }
    163    }