Java tutorial
//$HeadURL: svn+ssh://rbezema@svn.wald.intevation.org/deegree/base/branches/2.2_testing/src/org/deegree/io/util/FileMonitor.java $ /*---------------- FILE HEADER ------------------------------------------ This file is part of deegree. Copyright (C) 2001-2008 by: EXSE, Department of Geography, University of Bonn http://www.giub.uni-bonn.de/deegree/ lat/lon GmbH http://www.lat-lon.de This library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version. This library 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 Lesser General Public License for more details. You should have received a copy of the GNU Lesser General Public License along with this library; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA Contact: Andreas Poth lat/lon GmbH Aennchenstr. 19 53115 Bonn Germany E-Mail: poth@lat-lon.de Prof. Dr. Klaus Greve Department of Geography University of Bonn Meckenheimer Allee 166 53115 Bonn Germany E-Mail: greve@giub.uni-bonn.de ---------------------------------------------------------------------------*/ import java.io.File; import java.io.FileNotFoundException; import java.net.URL; import java.util.Hashtable; import java.util.Timer; import java.util.TimerTask; /** * Replaces inner class Reloader in AbstractOGCServlet. * * @author <a href="mailto:tfr@users.sourceforge.net">Torsten Friebe </A> * @author last edited by: $Author: apoth $ * * @version 2.0, $Revision: 9342 $, $Date: 2007-12-27 13:32:57 +0100 (Do, 27 Dez 2007) $ * * @see org.deegree.enterprise.AbstractOGCServlet * @see java.io.File#lastModified * @see <a href="http://www.javaworld.com/javaworld/javatips/jw-javatip125.html">Java Tip 125 </a> * * @since 2.0 */ public class FileMonitor { private static final FileMonitor instance = new FileMonitor(); private Timer timer; private Hashtable<String, FileMonitorTask> timerEntries; /** * Factory method to get singleton instance. * * @return * */ public static FileMonitor getInstance() { return instance; } protected FileMonitor() { // Create timer, run timer thread as daemon. timer = new Timer(true); timerEntries = new Hashtable<String, FileMonitorTask>(); } /** * Add a monitored file with a FileChangeListener. * * @param listener * listener to notify when the file changed. * @param fileName * name of the file to monitor. * @param period * polling period in milliseconds. */ public void addFileChangeListener(FileChangeListener listener, String fileName, long period) throws FileNotFoundException { removeFileChangeListener(listener, fileName); FileMonitorTask task = new FileMonitorTask(listener, fileName); timerEntries.put(fileName + listener.hashCode(), task); timer.schedule(task, period, period); } /** * Remove the listener from the notification list. * * @param listener * the listener to be removed. */ public void removeFileChangeListener(FileChangeListener listener, String fileName) { FileMonitorTask task = timerEntries.remove(fileName + listener.hashCode()); if (task != null) { task.cancel(); } } protected void fireFileChangeEvent(FileChangeListener listener, String fileName) { listener.fileChanged(fileName); } class FileMonitorTask extends TimerTask { FileChangeListener listener; String fileName; File monitoredFile; long lastModified; public FileMonitorTask(FileChangeListener listener, String fileName) throws FileNotFoundException { this.listener = listener; this.fileName = fileName; this.lastModified = 0; monitoredFile = new File(fileName); if (!monitoredFile.exists()) { // but is it on CLASSPATH? URL fileURL = listener.getClass().getClassLoader().getResource(fileName); if (fileURL != null) { monitoredFile = new File(fileURL.getFile()); } else { throw new FileNotFoundException("File Not Found: " + fileName); } } this.lastModified = monitoredFile.lastModified(); } public void run() { long lastModified = monitoredFile.lastModified(); if (lastModified != this.lastModified) { this.lastModified = lastModified; fireFileChangeEvent(this.listener, this.fileName); } } } } //$HeadURL: svn+ssh://rbezema@svn.wald.intevation.org/deegree/base/branches/2.2_testing/src/org/deegree/io/util/FileChangeListener.java $ /*---------------- FILE HEADER ------------------------------------------ This file is part of deegree. Copyright (C) 2001-2008 by: EXSE, Department of Geography, University of Bonn http://www.giub.uni-bonn.de/deegree/ lat/lon GmbH http://www.lat-lon.de This library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version. This library 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 Lesser General Public License for more details. You should have received a copy of the GNU Lesser General Public License along with this library; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA Contact: Andreas Poth lat/lon GmbH Aennchenstr. 19 53115 Bonn Germany E-Mail: poth@lat-lon.de Prof. Dr. Klaus Greve Department of Geography University of Bonn Meckenheimer Allee 166 53115 Bonn Germany E-Mail: greve@giub.uni-bonn.de ---------------------------------------------------------------------------*/ /** * @author <a href="mailto:tfr@users.sourceforge.net">Torsten Friebe </A> * * @author last edited by: $Author: apoth $ * * @version 2.0, $Revision: 9342 $, $Date: 2007-12-27 13:32:57 +0100 (Do, 27 Dez 2007) $ * * * @since 2.0 */ interface FileChangeListener { /** * Invoked when a file changes. * * @param fileName * name of changed file. */ public void fileChanged(String fileName); }