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/*******************************************************************************
* Copyright (c) 2004, 2007 Boeing.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* Boeing - initial API and implementation
*******************************************************************************/
package org.eclipse.osee.framework.skynet.core.utility;
import java.io.File;
import java.util.HashMap;
import java.util.HashSet;
import java.util.LinkedList;
import java.util.Map;
import java.util.Timer;
import java.util.TimerTask;
import java.util.concurrent.TimeUnit;
import java.util.logging.Level;
import org.eclipse.osee.framework.logging.OseeLog;
import org.eclipse.osee.framework.skynet.core.internal.Activator;
/**
* @author Ken J. Aguilar
*/
public class FileWatcher extends TimerTask {
private final long interval;
private final Timer timer = new Timer();
protected final HashMap<File, Long> filesToWatch = new HashMap<File, Long>(128);
private final HashSet<IFileWatcherListener> listeners = new HashSet<IFileWatcherListener>();
public FileWatcher(long time, TimeUnit unit) {
interval = unit.toMillis(time);
}
/**
* Starts the file watcher monitoring of the file system
*/
public void start() {
timer.schedule(this, interval, interval);
}
/**
* adds a {@link File} to the files to be monitored. This method can be called before or after the {@link #start()}
* method is called.
*/
public synchronized void addFile(File file) {
filesToWatch.put(file, file.lastModified());
}
/**
* removes a {@link File} from the set of files to be monitored. This method can be called before or after the
* {@link #start()} method is called.
*
* @return returns the last know timestamp of the file before it was removed or null if it was never being monitored
* in the first place
*/
public synchronized Long removeFile(File file) {
return filesToWatch.remove(file);
}
/**
* registers a listener who will be notified of file change events. This method can be called before or after the
* {@link #start()} method is called.
*/
public synchronized void addListener(IFileWatcherListener listener) {
listeners.add(listener);
}
/**
* unregisters a listener from receiving file change events. This method can be called before or after the
* {@link #start()} method is called.
*/
public synchronized void removeListener(IFileWatcherListener listener) {
listeners.remove(listener);
}
@Override
public synchronized void run() {
try {
LinkedList<FileChangeEvent> fileChangeEvents = new LinkedList<FileChangeEvent>();
for (Map.Entry<File, Long> entry : filesToWatch.entrySet()) {
Long latestLastModified = entry.getKey().lastModified();
Long storedLastModified = entry.getValue();
if (!storedLastModified.equals(latestLastModified)) {
entry.setValue(latestLastModified);
if (storedLastModified == 0) {
// created
assert entry.getKey().exists() : "file doesn't exist";
fileChangeEvents.add(new FileChangeEvent(entry.getKey(), FileChangeType.CREATED));
} else if (latestLastModified == 0) {
// deleted
assert !entry.getKey().exists() : "file still exist";
fileChangeEvents.add(new FileChangeEvent(entry.getKey(), FileChangeType.DELETED));
} else {
// modified
assert entry.getKey().exists() : "file doesn't exist";
fileChangeEvents.add(new FileChangeEvent(entry.getKey(), FileChangeType.MODIFIED));
}
}
}
if (!fileChangeEvents.isEmpty()) {
// there is at least one file change event, notify listeners
for (IFileWatcherListener listener : listeners) {
listener.filesModified(fileChangeEvents);
}
}
} catch (Exception ex) {
OseeLog.log(Activator.class, Level.SEVERE, ex);
}
}
public void dispose() {
timer.cancel();
listeners.clear();
filesToWatch.clear();
}
}
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