handle.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/type/Handle.java,v $
 * $Revision: 1.6 $
 * $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.type;

import java.net.InetAddress;
import java.net.UnknownHostException;

import java.util.List;
import java.util.ArrayList;

import jacomma.util.Cache;
import jacomma.util.Environment;

/**
 * TBA
 **/
public final class Handle implements Cloneable {
	
	String target_;
	String name_;
	InetAddress home_;
	List loc_;
	String string_;
	String id_;

	Handle( String target, String name, InetAddress home, List loc, String key ) {
		target_ = target;
		name_ = name;
		home_ = home;
		loc_ = loc;
		string_ = key;
		id_ = name + "@" + home.getHostName();
	}
	
	public String toString() {
		return string_;
	}
	
	public String id() {
		return id_;
	}
	
	public boolean sameAgent( Handle h ) {
		return name_.equals( h.getName() ) && home_.equals( h.getHome() );
	}

	public boolean equals( Object obj ) {
		try {
			return string_.equals( obj.toString() )
				&& ((Handle)obj).locations().equals( loc_ );
		} catch ( ClassCastException exc ) {
			return false;
		}
	}
	
	public int hashCode() {
		return string_.hashCode();
	}
	
	public String getName() {
		return name_;
	}

	public String getTarget() {
		return target_;
	}
	
	public Handle setTarget( String tgt ) {
		return createHandle( tgt, name_, home_, (List)((ArrayList)loc_).clone() );
	}

	public InetAddress getHome() {
		return home_;
	}

	public List locations() {
		return loc_;
	}	

	public Object clone() {
		try {
			Handle c = (Handle)super.clone();
			c.loc_ = (List)((ArrayList)loc_).clone();
			return c;
		} catch ( CloneNotSupportedException exc ) {
			throw new jacomma.util.CheckedException( exc );
		}
	}

	// factory methods + stuff
	static final Cache cache_;
	static final InetAddress localhost_;
	static final ArrayList defloc_;

	static {
		try {
			cache_  = new Cache();
			String cs = (String)Environment.getProperty( "icm.host" );
			localhost_ = ( cs == null ) ?
				InetAddress.getLocalHost() : InetAddress.getByName( cs );
			defloc_ = new ArrayList();
			defloc_.add( localhost_ );
		} catch ( UnknownHostException exc ) {
			throw new jacomma.util.CheckedException( exc );
		}
	}

	public static Handle createHandle( String name ) {
		return createHandle( null, name, localhost_, (List)defloc_.clone() );
	}

	public static Handle createHandle( String name, InetAddress home ) {
		List l = new ArrayList();
		l.add( home );
		return createHandle( null, name, home, l );
	}

	public static Handle createHandle( String target, String name ) {
		return createHandle( target, name, localhost_, (List)defloc_.clone() );
	}

	public static Handle createHandle( String target, String name, InetAddress home ) {
		List l = new ArrayList();
		l.add( home );
		return createHandle( target, name, home, l );
	}

	public static Handle createHandle( String name, InetAddress home, List loc ) {
		return createHandle( null, name, home, loc );
	}
	
	public static Handle createHandle( String target, String name, 
									   InetAddress home, InetAddress[] loc ) {
		List l = new ArrayList();
		for ( int i = 0; i < loc.length; i++ )
			l.add( loc[i] );
		
		return createHandle( target, name, home, l );
	}

	public static Handle createHandle( String target, String name, 
									   InetAddress home, List loc ) {
		String key =( (target == null) ? "" : (target + ":") ) 
			+ name + "@" + home.getHostName();
		
		Handle h = (Handle)cache_.get( key );
		if ( h == null ) {
			h = (Handle)cache_.try_put( key, new 
				Handle( target, name, home, loc, key ) );
		} else if ( !h.loc_.equals( loc ) ) {
			h = (Handle)h.clone();
			h.loc_ = loc;
		}

		return h;
	}
}