listcontentrequest.java

jxta-cms-src-2.4.zip 是官网上的比较稳定的CMS源代码。目前是最稳定的高版本。

/*
 * Copyright (c) 2001 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 THE APACHE SOFTWARE FOUNDATION 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 based on the BSD license adopted by the Apache Foundation.
 *
 * $Id: ListContentRequest.java,v 1.22 2006/02/07 20:43:51 bondolo Exp $
 *
 */

package net.jxta.share.client;

import java.util.Vector;
import java.util.Enumeration;
import net.jxta.share.ContentAdvertisement;
import net.jxta.share.ContentAdvertisementImpl;
import net.jxta.peergroup.PeerGroup;
import net.jxta.discovery.DiscoveryService;
import net.jxta.discovery.DiscoveryListener;
import net.jxta.discovery.DiscoveryEvent;

import org.apache.log4j.Logger;
import org.apache.log4j.Level;

/**
 * This class is used to search a peergroup for content that is being
 * shared using the JXTA CMS.
 * Search queries are propagated across the peergroup using the Resolver
 * and list responses are received using an EndpointListener.
 * 
 * @see CachedListContentRequest
 * @see ContentManager#share(File)
 * @see GetContentRequest
 * @see ListMessageProcessor
 * @see EndpointListener
 * @see ResolverService
 */

public class ListContentRequest implements DiscoveryListener {

    private final static transient Logger LOG = Logger.getLogger(ListContentRequest.class.getName());

    private PeerGroup group = null;
    protected String subString = null;

    private Vector results = new Vector();
    private DiscoveryService disco = null;

    private static int DEFAULT_THRESHOLD = 100;
    private static String NAME_ATTRIBUTE = "name";

    /**
     * Create a ListContentRequest to search a given peer group for content whose
     * name or description field contains a certain string.
     * @param group the peer group to search
     * @param inSubStr The string to search for.  Any content that has a name or
     * description that contains <code>inSubStr</code> (non case-sensitive) will
     * be added to the list of results.  If <code>inSubStr</code> is null or an
     * empty string, all content in the peer group will be returned as results.
     * @see #activateRequest()
     */
    public ListContentRequest(PeerGroup group, String inSubStr) {

        this.group = group;
        this.subString = inSubStr;

        //prevent it from searching for "null" if subString is null
        if(this.subString == null)
            this.subString = "";

        this.disco = (DiscoveryService) group.getDiscoveryService();

        // Makes sure that ContentAdvertisement is registered
        ContentAdvertisementImpl.registerAdvertisement();
    }

    /**
     * Start searching for content.
     * @see #cancel()
     */
    public void activateRequest() {

        disco.getRemoteAdvertisements (null,
                                       DiscoveryService.ADV,
                                       NAME_ATTRIBUTE,
                                       subString,
                                       DEFAULT_THRESHOLD,
                                       this);
    }



    /**
     * This function is called when the list of results received so far has
     * been updated.
     * @see #getResults()
     */
    public void notifyMoreResults() {}

    public void cancel() {
        // Remove our listener from Discovery
        disco.removeDiscoveryListener (this);
    }

    public String getSubString() {
        return subString;
    }

    /**
     * @return an array of all the ContentAdvertisements received so far.
     * @see #notifyMoreResults()
     */
    public ContentAdvertisement[] getResults() {
        ContentAdvertisement[] resultArray = new ContentAdvertisement[results.size()];
        results.copyInto(resultArray);
        return resultArray;
    }


    protected synchronized void addResult(ContentAdvertisement adv) {

        if (LOG.isEnabledFor(Level.DEBUG))
            LOG.debug("addResult() " + adv.toString());

        // check if we already have this ContentAdvertisement in the results
        if (!results.contains(adv)) {
            results.add(adv);
            if (LOG.isEnabledFor(Level.DEBUG))
                LOG.debug("result added ");
        }
    }

    public void finalize () {
        cancel();
    }


    /**
     * DiscoveryService Event
     * @param DiscoveryEvent event the discovery event
     */
    public void discoveryEvent (DiscoveryEvent event) {
        Enumeration advs = event.getSearchResults();

        if ((advs == null) || (!advs.hasMoreElements())) {
            // nothing received.
            return;
        }

        boolean gotSomething = false;

        while (advs.hasMoreElements()) {
            try {
                ContentAdvertisement adv = (ContentAdvertisement) advs.nextElement();
                addResult (adv);
                gotSomething = true;
            } catch (Exception ez) {
                continue;
            }
        }

        if (gotSomething) {
            notifyMoreResults();
        }
    }
}