limitedrangewalk.java

jxta平台的开发包

/************************************************************************
 *
 * $Id: LimitedRangeWalk.java,v 1.8 2004/06/04 04:42:19 bondolo Exp $
 *
 * Copyright (c) 2002 Sun Microsystems, Inc.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:
 *       "This product includes software developed by the
 *       Sun Microsystems, Inc. for Project JXTA."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Sun", "Sun Microsystems, Inc.", "JXTA" and "Project JXTA"
 *    must not be used to endorse or promote products derived from this
 *    software without prior written permission. For written
 *    permission, please contact Project JXTA at http://www.jxta.org.
 *
 * 5. Products derived from this software may not be called "JXTA",
 *    nor may "JXTA" appear in their name, without prior written
 *    permission of Sun.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL SUN MICROSYSTEMS OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of Project JXTA.  For more
 * information on Project JXTA, please see
 * <http://www.jxta.org/>.
 *
 * This license is bansed on the BSD license adopted by the Apache Foundation.
 *********************************************************************************/

package net.jxta.impl.rendezvous.limited;


import net.jxta.peergroup.PeerGroup;
import net.jxta.impl.rendezvous.*;
import net.jxta.impl.rendezvous.rpv.PeerView;


/**
 * This class is the Limited Walk Policy.
 *
 * @see net.jxta.impl.rendezvous.limited.LimitedRangeWalker
 * @see net.jxta.impl.rendezvous.limited.LimitedRangeGreeter
 */
public class LimitedRangeWalk extends RdvWalk {
    
    private LimitedRangeWalker walker = null;
    private LimitedRangeGreeter greeter = null;
    
    public LimitedRangeWalk(PeerGroup group,
            String serviceName,
            String serviceParam,
            PeerView  rpv) {
        super(group, serviceName, serviceParam, rpv);
    }
    
    /**
     *  {@inheritDoc}
     **/
    public synchronized RdvWalker  getWalker() {
        if (this.walker == null) {
            this.walker = new LimitedRangeWalker(group, this);
        }
        return this.walker;
    }
    
    /**
     *  {@inheritDoc}
     **/
    public synchronized RdvGreeter  getGreeter() {
        if (this.greeter == null) {
            this.greeter = new LimitedRangeGreeter(group, this);
        }
        return this.greeter;
    }
    
    /**
     *  {@inheritDoc}
     **/
    public synchronized void stop() {
        
        if (walker != null) {
            walker.stop();
            walker = null;
        }
        
        if (greeter != null) {
            greeter.stop();
            greeter = null;
        }
        
        super.stop();
    }
}