/*
* Copyright (c) 2003, 2004 Rafael Steil
* All rights reserved.
*
* Redistribution and use in source and binary forms,
* with or without modification, are permitted provided
* that the following conditions are met:
*
* 1) Redistributions of source code must retain the above
* copyright notice, this list of conditions and the
* following disclaimer.
* 2) Redistributions in binary form must reproduce the
* above copyright notice, this list of conditions and
* the following disclaimer in the documentation and/or
* other materials provided with the distribution.
* 3) Neither the name of "Rafael Steil" nor
* the names of its contributors may be used to endorse
* or promote products derived from this software without
* specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT
* HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING,
* BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
* THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA,
* OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER
* IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
* ADVISED OF THE POSSIBILITY OF SUCH DAMAGE
*
* Created on 02/06/2004 23:29:51
* The JForum Project
* http://www.jforum.net
*/
package net.jforum.util;
import java.io.File;
import java.util.HashMap;
import java.util.Map;
import java.util.Timer;
import java.util.TimerTask;
import org.apache.log4j.Logger;
/**
* Monitor class for file changes.
*
* @author Rafael Steil
* @version $Id: FileMonitor.java,v 1.9 2007/04/12 02:11:53 rafaelsteil Exp $
*/
public class FileMonitor
{
private static Logger logger = Logger.getLogger(FileMonitor.class);
private static final FileMonitor instance = new FileMonitor();
private Timer timer;
private Map timerEntries;
private FileMonitor() {
this.timerEntries = new HashMap();
this.timer = new Timer(true);
}
public static FileMonitor getInstance() {
return instance;
}
/**
* Add a file to the monitor
*
* @param listener The file listener
* @param filename The filename to watch
* @param period The watch interval.
*/
public void addFileChangeListener(FileChangeListener listener,
String filename, long period) {
this.removeFileChangeListener(filename);
logger.info("Watching " + filename);
FileMonitorTask task = new FileMonitorTask(listener, filename);
this.timerEntries.put(filename, task);
this.timer.schedule(task, period, period);
}
/**
* Stop watching a file
*
* @param listener The file listener
* @param filename The filename to keep watch
*/
public void removeFileChangeListener(String filename) {
FileMonitorTask task = (FileMonitorTask)this.timerEntries.remove(filename);
if (task != null) {
task.cancel();
}
}
private static class FileMonitorTask extends TimerTask {
private FileChangeListener listener;
private String filename;
private File monitoredFile;
private long lastModified;
public FileMonitorTask(FileChangeListener listener, String filename) {
this.listener = listener;
this.filename = filename;
this.monitoredFile = new File(filename);
if (!this.monitoredFile.exists()) {
return;
}
this.lastModified = this.monitoredFile.lastModified();
}
public void run() {
long latestChange = this.monitoredFile.lastModified();
if (this.lastModified != latestChange) {
this.lastModified = latestChange;
this.listener.fileChanged(this.filename);
}
}
}
}