Java/File Input Output/File Monoitor

File Monitor Demo

    
//$HeadURL: svn+ssh://rbezema@svn.wald.intevation.org/deegree/base/branches/2.2_testing/src/org/deegree/io/util/FileMonitor.java $
/*----------------    FILE HEADER  ------------------------------------------
 This file is part of deegree.
 Copyright (C) 2001-2008 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
 
 ---------------------------------------------------------------------------*/

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 
 * 
 * @author last edited by: $Author: apoth $
 * 
 * @version 2.0, $Revision: 9342 $, $Date: 2007-12-27 13:32:57 +0100 (Do, 27 Dez 2007) $
 * 
 * 
 * @since 2.0
 */
interface FileChangeListener {
    /**
     * Invoked when a file changes.
     * 
     * @param fileName
     *            name of changed file.
     */
    public void fileChanged(String fileName);
}

Monitor files for changes

 
// Copyright (C) 2007 Google Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

import java.io.File;
import java.util.Hashtable;
import java.util.Timer;
import java.util.TimerTask;
/**
 * Monitor files for changes. This singleton class maintains a map of files to
 * monitor and objects to notify when something they change.
 */
public class FileMonitor {
  private static final FileMonitor SINGLETON = new FileMonitor();
  private Timer timer;
  private Hashtable<String, TimerTask> timerTasks;
  private FileMonitor() {
    timer = new Timer(true);
    timerTasks = new Hashtable<String, TimerTask>();
  }
  /**
   * Returns the singleton instance of this class.
   * @return the singleton instance
   */
  public static FileMonitor getInstance() {
    return SINGLETON;
  }
  /**
   * Start monitoring a file.
   * 
   * @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) {
    removeFileChangeListener(listener, fileName);
    FileMonitorTask task = new FileMonitorTask(listener, fileName);
    timerTasks.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) timerTasks.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) {
      this.listener = listener;
      this.fileName = fileName;
      this.lastModified = 0;
      monitoredFile = new File(fileName);
      this.lastModified = getLastModified();
    }
    private long getLastModified() {
      if (monitoredFile.exists()) { 
        return monitoredFile.lastModified();
      } else {
        return -1;
      }
    }
    @Override
    public void run() {
      long lastModified = getLastModified();
      if (lastModified != this.lastModified) {
        this.lastModified = lastModified;
        fireFileChangeEvent(this.listener, this.fileName);
      }
    }
  }
  
  public interface FileChangeListener {
    public void fileChanged(String fileName);
  }
}

Monitoring a File for changes.

 
/*******************************************************************************
 * Copyright (c) 2007 Pascal Essiembre.
 * 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:
 *    Pascal Essiembre - initial API and implementation
 ******************************************************************************/
import java.io.File;
import java.io.FileNotFoundException;
import java.net.URL;
import java.util.Hashtable;
import java.util.Timer;
import java.util.TimerTask;
/**
 * Class monitoring a {@link File} for changes.
 * 
 * @author Pascal Essiembre
 */
public class FileMonitor {
  private static final FileMonitor instance = new FileMonitor();
  private Timer timer;
  private Hashtable<String, FileMonitorTask> timerEntries;
  /**
   * Gets the file monitor instance.
   * 
   * @return file monitor instance
   */
  public static FileMonitor getInstance() {
    return instance;
  }
  /**
   * Constructor.
   */
  private FileMonitor() {
    // Create timer, run timer thread as daemon.
    timer = new Timer(true);
    timerEntries = new Hashtable<String, FileMonitorTask>();
  }
  /**
   * Adds a monitored file with a {@link 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 {
    addFileChangeListener(listener, new File(fileName), period);
  }
  /**
   * Adds 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, File file, long period)
      throws FileNotFoundException {
    removeFileChangeListener(listener, file);
    FileMonitorTask task = new FileMonitorTask(listener, file);
    timerEntries.put(file.toString() + 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) {
    removeFileChangeListener(listener, new File(fileName));
  }
  /**
   * Remove the listener from the notification list.
   * 
   * @param listener
   *          the listener to be removed.
   */
  public void removeFileChangeListener(FileChangeListener listener, File file) {
    FileMonitorTask task = timerEntries.remove(file.toString() + listener.hashCode());
    if (task != null) {
      task.cancel();
    }
  }
  /**
   * Fires notification that a file changed.
   * 
   * @param listener
   *          file change listener
   * @param file
   *          the file that changed
   */
  protected void fireFileChangeEvent(FileChangeListener listener, File file) {
    listener.fileChanged(file);
  }
  /**
   * File monitoring task.
   */
  class FileMonitorTask extends TimerTask {
    FileChangeListener listener;
    File monitoredFile;
    long lastModified;
    public FileMonitorTask(FileChangeListener listener, File file) throws FileNotFoundException {
      this.listener = listener;
      this.lastModified = 0;
      monitoredFile = file;
      if (!monitoredFile.exists()) { // but is it on CLASSPATH?
        URL fileURL = listener.getClass().getClassLoader().getResource(file.toString());
        if (fileURL != null) {
          monitoredFile = new File(fileURL.getFile());
        } else {
          throw new FileNotFoundException("File Not Found: " + file);
        }
      }
      this.lastModified = monitoredFile.lastModified();
    }
    public void run() {
      long lastModified = monitoredFile.lastModified();
      if (lastModified != this.lastModified) {
        this.lastModified = lastModified;
        fireFileChangeEvent(this.listener, monitoredFile);
      }
    }
  }
}
/*******************************************************************************
 * Copyright (c) 2007 Pascal Essiembre. 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: Pascal Essiembre - initial API and implementation
 ******************************************************************************/
/**
 * Listener interested in {@link File} changes.
 * 
 * @author Pascal Essiembre
 */
interface FileChangeListener {
  /**
   * Invoked when a file changes.
   * 
   * @param fileName
   *          name of changed file.
   */
  public void fileChanged(File file);
}

Utility class for synchronizing files/directories

    
//$Id: FileHelper.java 15522 2008-11-05 20:06:43Z hardy.ferentschik $
//Revised from hibernate search util
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.nio.channels.FileChannel;
import java.util.Arrays;
import java.util.HashSet;
import java.util.Set;

/**
 * Utility class for synchronizing files/directories.
 *
 * @author Emmanuel Bernard
 * @author Sanne Grinovero
 * @author Hardy Ferentschik
 */
public abstract class FileHelper {
  private static final int FAT_PRECISION = 2000;
  public static final long DEFAULT_COPY_BUFFER_SIZE = 16 * 1024 * 1024; // 16 MB

  public static boolean areInSync(File source, File destination) throws IOException {
    if ( source.isDirectory() ) {
      if ( !destination.exists() ) {
        return false;
      }
      else if ( !destination.isDirectory() ) {
        throw new IOException(
            "Source and Destination not of the same type:"
                + source.getCanonicalPath() + " , " + destination.getCanonicalPath()
        );
      }
      String[] sources = source.list();
      Set<String> srcNames = new HashSet<String>( Arrays.asList( sources ) );
      String[] dests = destination.list();
      // check for files in destination and not in source
      for ( String fileName : dests ) {
        if ( !srcNames.contains( fileName ) ) {
          return false;
        }
      }
      boolean inSync = true;
      for ( String fileName : sources ) {
        File srcFile = new File( source, fileName );
        File destFile = new File( destination, fileName );
        if ( !areInSync( srcFile, destFile ) ) {
          inSync = false;
          break;
        }
      }
      return inSync;
    }
    else {
      if ( destination.exists() && destination.isFile() ) {
        long sts = source.lastModified() / FAT_PRECISION;
        long dts = destination.lastModified() / FAT_PRECISION;
        return sts == dts;
      }
      else {
        return false;
      }
    }
  }
  public static void synchronize(File source, File destination, boolean smart) throws IOException {
    synchronize( source, destination, smart, DEFAULT_COPY_BUFFER_SIZE );
  }
  public static void synchronize(File source, File destination, boolean smart, long chunkSize) throws IOException {
    if ( chunkSize <= 0 ) {
      System.out.println("Chunk size must be positive: using default value." );
      chunkSize = DEFAULT_COPY_BUFFER_SIZE;
    }
    if ( source.isDirectory() ) {
      if ( !destination.exists() ) {
        if ( !destination.mkdirs() ) {
          throw new IOException( "Could not create path " + destination );
        }
      }
      else if ( !destination.isDirectory() ) {
        throw new IOException(
            "Source and Destination not of the same type:"
                + source.getCanonicalPath() + " , " + destination.getCanonicalPath()
        );
      }
      String[] sources = source.list();
      Set<String> srcNames = new HashSet<String>( Arrays.asList( sources ) );
      String[] dests = destination.list();
      //delete files not present in source
      for ( String fileName : dests ) {
        if ( !srcNames.contains( fileName ) ) {
          delete( new File( destination, fileName ) );
        }
      }
      //copy each file from source
      for ( String fileName : sources ) {
        File srcFile = new File( source, fileName );
        File destFile = new File( destination, fileName );
        synchronize( srcFile, destFile, smart, chunkSize );
      }
    }
    else {
      if ( destination.exists() && destination.isDirectory() ) {
        delete( destination );
      }
      if ( destination.exists() ) {
        long sts = source.lastModified() / FAT_PRECISION;
        long dts = destination.lastModified() / FAT_PRECISION;
        //do not copy if smart and same timestamp and same length
        if ( !smart || sts == 0 || sts != dts || source.length() != destination.length() ) {
          copyFile( source, destination, chunkSize );
        }
      }
      else {
        copyFile( source, destination, chunkSize );
      }
    }
  }
  private static void copyFile(File srcFile, File destFile, long chunkSize) throws IOException {
    FileInputStream is = null;
    FileOutputStream os = null;
    try {
      is = new FileInputStream( srcFile );
      FileChannel iChannel = is.getChannel();
      os = new FileOutputStream( destFile, false );
      FileChannel oChannel = os.getChannel();
      long doneBytes = 0L;
      long todoBytes = srcFile.length();
      while ( todoBytes != 0L ) {
        long iterationBytes = Math.min( todoBytes, chunkSize );
        long transferredLength = oChannel.transferFrom( iChannel, doneBytes, iterationBytes );
        if ( iterationBytes != transferredLength ) {
          throw new IOException(
              "Error during file transfer: expected "
                  + iterationBytes + " bytes, only " + transferredLength + " bytes copied."
          );
        }
        doneBytes += transferredLength;
        todoBytes -= transferredLength;
      }
    }
    finally {
      if ( is != null ) {
        is.close();
      }
      if ( os != null ) {
        os.close();
      }
    }
    boolean successTimestampOp = destFile.setLastModified( srcFile.lastModified() );
    if ( !successTimestampOp ) {
      System.out.println("Could not change timestamp for {}. Index synchronization may be slow. " + destFile );
    }
  }
  public static void delete(File file) {
    if ( file.isDirectory() ) {
      for ( File subFile : file.listFiles() ) {
        delete( subFile );
      }
    }
    if ( file.exists() ) {
      if ( !file.delete() ) {
        System.out.println( "Could not delete {}" + file );
      }
    }
  }
}