Application: gvSIG desktop

/*

 * $Id: Housekeeper.java 5819 2006-06-14 07:29:09Z cesar $

 * IzPack

 * Copyright (C) 2002 by Elmar Grom

 *

 * File :               Housekeeper.java

 * Description :        Performs housekeeping and cleanup tasks for IzForge

 * Author's email :     elmar@grom.net

 * Website :            http://www.izforge.com

 *

 * This program is free software; you can redistribute it and/or

 * modify it under the terms of the GNU General Public License

 * as published by the Free Software Foundation; either version 2

 * of the License, or any later version.

 *

 * This program 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 General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program; if not, write to the Free Software

 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.

 */

package   com.izforge.izpack.util;

import java.util.Vector;

/*---------------------------------------------------------------------------*/

/**

 * This class performs housekeeping and cleanup tasks. There can only be one

 * instance of <code>Housekeeper</code> per Java runtime, therefore this class

 * is implemented as a 'Singleton'.

 * <br><br>

 * It is VERY important to perform pre-shutdown cleanup operations through

 * this class. Do NOT rely on operations like <code>deleteOnExit()</code>

 * shutdown hooks or <code>finalize()</code>for cleanup. Because

 * <code>shutDown()</code> uses <code>System.exit()</code> to terminate,

 * these methods will not work at all or will not work reliably.

 *

 * @version  0.0.1 / 2/9/02

 * @author   Elmar Grom

 */

/*---------------------------------------------------------------------------*/

public class Housekeeper

{

  // ------------------------------------------------------------------------

  // Variable Declarations

  // ------------------------------------------------------------------------

  private static Housekeeper me = null;

  private Vector    cleanupClients  = new Vector ();

 /*--------------------------------------------------------------------------*/

 /**

  * This class is implemented as a 'Singleton'. Therefore the constructor is

  * private to prevent instantiation of this class. Use <code>getInstance()</code>

  * to obtain an instance for use.

  * <br><br>

  * For more information about the 'Singleton' pattern I highly recommend

  * the book Design Patterns by Gamma, Helm, Johnson and Vlissides

  * ISBN 0-201-63361-2. 

  */

 /*--------------------------------------------------------------------------*/

  private Housekeeper () {}

 /*--------------------------------------------------------------------------*/

 /**

  * Returns an instance of <code>Housekeeper</code> to use.

  *

  * @return    an instance of <code>Housekeeper</code>.

  */

 /*--------------------------------------------------------------------------*/

  public static Housekeeper getInstance ()

  {

    if (me == null)

    {

      me = new Housekeeper ();

    }

    return (me);

  }

 /*--------------------------------------------------------------------------*/

 /**

  * Use to register objects that need to perform cleanup operations before the

  * application shuts down.

  *

  * @param     client   reference of to an object that needs to perform

  *                     cleanup operations.

  */

 /*--------------------------------------------------------------------------*/

  public void registerForCleanup (CleanupClient client)

  {

    cleanupClients.add (client);

  }

 /*--------------------------------------------------------------------------*/

 /**

  * This methods shuts the application down. First, it will call all clients

  * that have registered for cleanup operations. Once this has been

  * accomplished, the application will be forceably terminated.

  * <br><br>

  * <b>THIS METHOD DOES NOT RETURN!</b>

  *

  * @param    exitCode    the exit code that should be returned to the

  *                       calling process.

  */

 /*--------------------------------------------------------------------------*/

  public void shutDown (int exitCode)

  {

    for (int i = 0; i < cleanupClients.size (); i++)

    {

      try

      {

        ((CleanupClient)cleanupClients.elementAt (i)).cleanUp ();

      }

      catch (Throwable exception)

      {

        // At this point we can not afford to treat exceptions. Cleanup that

        // can not be completed might unfortunately leave some garbage behind.

        // If we have a logging module, any exceptions received here should

        // be written to the log.

      }

    }

    System.exit (exitCode);

  }

}

/*---------------------------------------------------------------------------*/