encoderregistryimp.java

Java Communicating Agents是一个用于开发网络反应式信息agent的框架

/*
 * $Source: /home/data/cvsroot/src/jacomma/icm/io/imp/EncoderRegistryImp.java,v $
 * $Revision: 1.7 $
 * $Date: 2000/10/28 20:09:07 $
 *
 * This file is part of the jacomma framework
 * Copyright (c) 2000 	Dimitrios Vyzovitis
 *			mailto:[e-mail]
 *			
 *
 *			
 *			
 *			
 *
 *	This library is free software; you can redistribute it and/or modify
 *	it under the terms of the GNU Library General Public License as published by
 *	the Free Software Foundation; either version 2 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 Library General Public License for more details.
 *
 *	You should have received a copy of the GNU Library 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
 */

package jacomma.icm.io.imp;

import jacomma.icm.io.ObjectEncoder;

import jacomma.util.Environment;
import jacomma.util.RdWrMap;
import jacomma.util.CheckedException;
import jacomma.util.TypeIterator;
import jacomma.util.ArrayTypeIterator;

import java.util.Iterator;
import java.util.Map;
import java.util.StringTokenizer;
import java.util.ArrayList;
import java.util.List;

import java.lang.reflect.Array;

/**
 * TBA
 **/
public class EncoderRegistryImp implements ObjectEncoder.Registry {

	RdWrMap all_ = new RdWrMap();
	RdWrMap some_ = new RdWrMap();
		
	public EncoderRegistryImp() {}

	public void load( java.util.Properties prop ) {
		for ( Iterator it = prop.entrySet().iterator();
			  it.hasNext(); ) try {
				  Map.Entry next = (Map.Entry)it.next();
				  String key = (String)next.getKey();
				  if ( "registry".equals( key ) ) continue;
				  
				  ArrayList types = new ArrayList();
				  for ( StringTokenizer tok = new StringTokenizer( (String)next.getValue() );
						tok.hasMoreTokens(); ) {
					  String cn = tok.nextToken();
					  if ( cn.endsWith( ".array" ) )
						  types.add( Array.newInstance( Class.forName( cn.substring( 0, cn.lastIndexOf( ".array" ) ) ), 0 ).getClass() );
					  else
						  types.add( Class.forName( cn ) );
				  }
				  
				  registerEncoder( types, Class.forName( key ) );
			  } catch ( Exception exc ) {
				  exc.printStackTrace();
			  }
	}

	public ObjectEncoder getEncoder( Object obj ) {
		// Check for specially suited Encoders
		TypeIterator t = obj.getClass().isArray() ?
			new ArrayTypeIterator( obj.getClass().getComponentType() )
				: new TypeIterator( obj );
		ObjectEncoder enc = null;
		Class c = null;

		while( enc == null && t.hasMoreTypes() ) {
			c = t.nextType();
			List l = (List)some_.get( c );
			if ( l != null )
				for ( Iterator it = l.iterator();
					  enc == null && it.hasNext(); ) {
					enc = (ObjectEncoder)it.next();
					if ( !enc.canHandleSome( c ) || !enc.canHandle( obj ) )
						enc = null; // not good
				}
		}

		if ( enc == null ) // nothing specially tuned for the object
			enc = getEncoder( obj.getClass() ); // default hierarchy
		else if ( !c.equals( obj.getClass() ) ) // partial hierarchy - can do it
			registerEncoder( c, enc );
		
		return enc;
	}

	public ObjectEncoder getEncoder( Class target ) {
		TypeIterator t = target.isArray() ?
			new ArrayTypeIterator( target.getComponentType() )
				: new TypeIterator( target );
		ObjectEncoder enc = null;
		Class c = null;

		while( enc == null && t.hasMoreTypes() ) {
			c = t.nextType();
			enc = (ObjectEncoder)all_.get( c );
		}
		
		if ( enc != null && !c.equals( target ) )
			enc = (ObjectEncoder)all_.try_put( target, enc ); // double-checked locking
		
		return enc;
	}


	public void registerEncoder( java.util.Collection types, Class c ) {
		try {
			ObjectEncoder enc = (ObjectEncoder)c.newInstance();
			for ( Iterator it = types.iterator();
				  it.hasNext();
				  registerEncoder( (Class)it.next(), enc ) );
		} catch ( InstantiationException exc ) {
			throw new CheckedException( exc );
		} catch ( IllegalAccessException exc ) {
			throw new CheckedException( exc );
		}
	}

	public void registerEncoder( Class c, ObjectEncoder enc ) {
		if ( enc.canHandle( c ) )
			all_.put( c, enc );
		else if ( enc.canHandleSome( c ) ) {
			some_.lock.wrlock();
			try {
				List l = (List)some_.get( c );
				if ( l == null ) {
					l = new ArrayList();
					some_.put( c, l );
				}
				if ( !l.contains( enc ) )
					l.add( enc );
			} finally {
				some_.lock.unlock();
			}
		} else
			throw new IllegalArgumentException( "Bad Encoder: " + enc
												+ "[" + c.getName() + "]" );
	}

	public void unregisterEncoder( Class c, ObjectEncoder enc ) {
		// Only partial encoders.
		some_.lock.wrlock();
		try {
			List l;
			if ( (l = (List)some_.get( c )) != null )
				some_.remove( enc );
		} finally {
			some_.lock.unlock();
		}
	}
	
	public void dump() {
		all_.dump();
		some_.dump();
	}
	

}