netmessagefactory.java

Vyger offers a D & D and Rogue-like environment in a graphical online roleplay game.

/*
 * Light And Shadow. A Persistent Universe based on Robert Jordan's Wheel of Time Books.
 * Copyright (C) 2001-2002 WOTLAS Team
 *
 * 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 (at your option) 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 wotlas.libs.net;

import java.io.File;
import java.util.Hashtable;

import wotlas.libs.net.message.*;

import wotlas.utils.Debug;
import wotlas.utils.Tools;


/** For one NetMessage representing message data, there can be only one NetMessageBehaviour
 *  available on each side (local, remote). Therefore this Message Factory keeps in a table all the 
 *  message behaviour classes and their associated message data class name.
 *  We can then create message behaviour when they are wanted, given their super class name.
 * 
 * @author Aldiss
 * @see wotlas.libs.net.NetMessage
 * @see wotlas.libs.net.NetMessageBehaviour
 */

public class NetMessageFactory {

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

  /** Default message factory (one per default ClassLoader).
   */
     private static NetMessageFactory msgFactory;

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

  /** MessageBehaviour Classes, ordered by their mother class ( NetMessage child )
   */
     private Hashtable msgClasses;

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

  /** Static initialization.
   */
     static {
     	 msgFactory = new NetMessageFactory();
     }

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

  /** To get the default MessageFactory.
   * @return the default NetMessageFactory
   */
     protected static NetMessageFactory getMessageFactory() {
           return msgFactory;
     }

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

  /** Protected Empty Constructor. 
   */
     protected NetMessageFactory() {
//     	msgClasses = new Hashtable(50);
     	msgClasses = new Hashtable(90);

       // We add system messages.
         addMessage( ServerWelcomeMsgBehaviour.class );
         addMessage( ServerErrorMsgBehaviour.class );
         addMessage( ClientRegisterMsgBehaviour.class );
         addMessage( EndOfConnectionMsgBehaviour.class );
         addMessage( PingMsgBehaviour.class );
     }

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

  /** Adds new messages to the NetMessageFactory. You have to give the name of the packages
   *  where the message behaviour classes can be found. They are searched on the disk from
   *  current system directory.<br>
   *
   *  We don't check if the packages have already been added. Old message behaviour classes
   *  are replaced if they where already defined in the factory.
   *
   * @param packagesName a list of packages where we can find NetMsgBehaviour Classes.
   * @return the number of loaded messages.
   */
     protected int addMessagePackages( String packagesName[] ) {
          if(packagesName==null || packagesName.length==0)
              return 0;

       // we search NetMessageBehaviour classes
          Class classes[] = null;
       
          try{
              classes = Tools.getImplementorsOf("wotlas.libs.net.NetMessageBehaviour", packagesName );
          }
          catch( ClassNotFoundException e ) {
              Debug.signal(Debug.CRITICAL, this, e );
              return 0;
          }
          catch( SecurityException e ) {
              Debug.signal(Debug.CRITICAL, this, e );
              return 0;
          }
          catch( RuntimeException e ) {
              Debug.signal(Debug.ERROR, this, e );
              return 0;
          }

          if(classes==null || classes.length==0)
             return 0;

       // We add the found classes to our list
          int nbMsg = 0;
            
          for( int i=0; i<classes.length; i++)
              if( addMessage( classes[i] ) )
                  nbMsg++;
         
          return nbMsg;
     }

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

  /** Adds a new NetMessageBehaviour class to our list.
   *
   * @param packageName a package name where we can find NetMsgBehaviour Classes.
   * @return true if the message has been accepted
   */
     protected boolean addMessage( Class classToAdd ) {

           if( classToAdd==null || classToAdd.isInterface() )
              return false;

           try {
              Object o = classToAdd.newInstance();

              if( !(o instanceof NetMessage) || !(o instanceof NetMessageBehaviour) ) {
                  Debug.signal( Debug.ERROR, this, "Provided class has a bad network message format ! "+classToAdd );
                  return false;
              }
           }
           catch( Exception e ) {
               Debug.signal( Debug.ERROR, this, e );
               return false;
           }
 
         // Ok, we have a valid Message Behaviour Class.
           msgClasses.put( classToAdd.getSuperclass().getName(), classToAdd );

           // Debug.signal(Debug.NOTICE, null, "Added Msg "+classToAdd);
           return true;
     }

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

  /** To get a new instance of a NetMessageBehaviour given its super class name
   *  associated (NetMessage). This method is used by the NetReceiver to reconstruct
   *  the received messages.
   *
   * @param msgSuperClassName the message's super class name.
   * @return a new instance of the wanted NetMessageBehaviour.
   * @exception ClassNotFoundException if there is no associated class for the given name.
   * @exception InstantiationException should never occur since we instanciate the class in
   *            the addMessagePackage(s) method.
   * @exception IllegalAccessException if the class access has been secured.
   */
     public NetMessageBehaviour getNewMessageInstance( String msgSuperClassName )
     throws ClassNotFoundException, InstantiationException, IllegalAccessException {

         Class searchedClass = (Class) msgClasses.get( msgSuperClassName );

         if( searchedClass==null ){
             System.out.println(" uhm wrong class, you should declare the package u'r using!");
             throw new ClassNotFoundException(msgSuperClassName);
         }

         return (NetMessageBehaviour) searchedClass.newInstance();
     }

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

}