/*---------------- FILE HEADER ------------------------------------------
This file is part of deegree.
Copyright (C) 2001-2006 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
---------------------------------------------------------------------------*/
package org.deegree.io.util;
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: poth $
*
* @version 2.0, $Revision: 1.7 $, $Date: 2006/07/12 14:46:17 $
*
* @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 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();
}
/**
* 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 = (FileMonitorTask) 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 );
}
}
}
}/* ********************************************************************
Changes to this class. What the people have been up to:
$Log: FileMonitor.java,v $
Revision 1.7 2006/07/12 14:46:17 poth
comment footer added
********************************************************************** */