001 //$HeadURL: https://svn.wald.intevation.org/svn/deegree/base/branches/2.3_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 }