001 //$HeadURL: svn+ssh://rbezema@svn.wald.intevation.org/deegree/base/branches/2.2_testing/src/org/deegree/io/util/FileMonitor.java $
002 /*---------------- FILE HEADER ------------------------------------------
003
004 This file is part of deegree.
005 Copyright (C) 2001-2008 by:
006 EXSE, Department of Geography, University of Bonn
007 http://www.giub.uni-bonn.de/deegree/
008 lat/lon GmbH
009 http://www.lat-lon.de
010
011 This library is free software; you can redistribute it and/or
012 modify it under the terms of the GNU Lesser General Public
013 License as published by the Free Software Foundation; either
014 version 2.1 of the License, or (at your option) any later version.
015
016 This library is distributed in the hope that it will be useful,
017 but WITHOUT ANY WARRANTY; without even the implied warranty of
018 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
019 Lesser General Public License for more details.
020
021 You should have received a copy of the GNU Lesser General Public
022 License along with this library; if not, write to the Free Software
023 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
024
025 Contact:
026
027 Andreas Poth
028 lat/lon GmbH
029 Aennchenstr. 19
030 53115 Bonn
031 Germany
032 E-Mail: poth@lat-lon.de
033
034 Prof. Dr. Klaus Greve
035 Department of Geography
036 University of Bonn
037 Meckenheimer Allee 166
038 53115 Bonn
039 Germany
040 E-Mail: greve@giub.uni-bonn.de
041
042
043 ---------------------------------------------------------------------------*/
044
045 package org.deegree.io.util;
046
047 import java.io.File;
048 import java.io.FileNotFoundException;
049 import java.net.URL;
050 import java.util.Hashtable;
051 import java.util.Timer;
052 import java.util.TimerTask;
053
054 /**
055 * Replaces inner class Reloader in AbstractOGCServlet.
056 *
057 * @author <a href="mailto:tfr@users.sourceforge.net">Torsten Friebe </A>
058 * @author last edited by: $Author: apoth $
059 *
060 * @version 2.0, $Revision: 9342 $, $Date: 2007-12-27 13:32:57 +0100 (Do, 27 Dez 2007) $
061 *
062 * @see org.deegree.enterprise.AbstractOGCServlet
063 * @see java.io.File#lastModified
064 * @see <a href="http://www.javaworld.com/javaworld/javatips/jw-javatip125.html">Java Tip 125 </a>
065 *
066 * @since 2.0
067 */
068
069 public class FileMonitor {
070
071 private static final FileMonitor instance = new FileMonitor();
072
073 private Timer timer;
074
075 private Hashtable<String, FileMonitorTask> timerEntries;
076
077 /**
078 * Factory method to get singleton instance.
079 *
080 * @return
081 *
082 */
083 public static FileMonitor getInstance() {
084 return instance;
085 }
086
087 protected FileMonitor() {
088 // Create timer, run timer thread as daemon.
089 timer = new Timer( true );
090 timerEntries = new Hashtable<String, FileMonitorTask>();
091 }
092
093 /**
094 * Add a monitored file with a FileChangeListener.
095 *
096 * @param listener
097 * listener to notify when the file changed.
098 * @param fileName
099 * name of the file to monitor.
100 * @param period
101 * polling period in milliseconds.
102 */
103 public void addFileChangeListener( FileChangeListener listener, String fileName, long period )
104 throws FileNotFoundException {
105 removeFileChangeListener( listener, fileName );
106 FileMonitorTask task = new FileMonitorTask( listener, fileName );
107 timerEntries.put( fileName + listener.hashCode(), task );
108 timer.schedule( task, period, period );
109 }
110
111 /**
112 * Remove the listener from the notification list.
113 *
114 * @param listener
115 * the listener to be removed.
116 */
117 public void removeFileChangeListener( FileChangeListener listener, String fileName ) {
118 FileMonitorTask task = timerEntries.remove( fileName + listener.hashCode() );
119 if ( task != null ) {
120 task.cancel();
121 }
122 }
123
124 protected void fireFileChangeEvent( FileChangeListener listener, String fileName ) {
125 listener.fileChanged( fileName );
126 }
127
128 class FileMonitorTask extends TimerTask {
129
130 FileChangeListener listener;
131
132 String fileName;
133
134 File monitoredFile;
135
136 long lastModified;
137
138 public FileMonitorTask( FileChangeListener listener, String fileName ) throws FileNotFoundException {
139 this.listener = listener;
140 this.fileName = fileName;
141 this.lastModified = 0;
142
143 monitoredFile = new File( fileName );
144 if ( !monitoredFile.exists() ) { // but is it on CLASSPATH?
145 URL fileURL = listener.getClass().getClassLoader().getResource( fileName );
146 if ( fileURL != null ) {
147 monitoredFile = new File( fileURL.getFile() );
148 } else {
149 throw new FileNotFoundException( "File Not Found: " + fileName );
150 }
151 }
152 this.lastModified = monitoredFile.lastModified();
153 }
154
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 }