discoveryquery.java

jxta_src_2.41b jxta 2.41b 最新版源码 from www.jxta.org

/*
 * Copyright (c) 2001-2006 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 based on the BSD license adopted by the Apache Foundation.
 *
 * $Id: DiscoveryQuery.java,v 1.37 2006/05/30 20:53:50 hamada Exp $
 */

package net.jxta.impl.protocol;

import java.lang.reflect.UndeclaredThrowableException;
import java.util.Enumeration;

import net.jxta.discovery.DiscoveryService;
import net.jxta.document.Document;
import net.jxta.document.Element;
import net.jxta.document.MimeMediaType;
import net.jxta.document.StructuredDocument;
import net.jxta.document.StructuredDocumentFactory;
import net.jxta.document.StructuredTextDocument;
import net.jxta.document.XMLDocument;
import net.jxta.document.XMLElement;
import net.jxta.protocol.DiscoveryQueryMsg;
import net.jxta.protocol.PeerAdvertisement;

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

/**
 * Implements the Discovery Query Message according to the schema defined by the
 * standard JXTA Peer Discovery Protocol (PDP).
 *
 * <p/><pre>
 * &lt;xs:element name="DiscoveryQuery" type="jxta:DiscoveryQuery"/>
 *
 * &lt;xsd:simpleType name="DiscoveryQueryType">
 *   &lt;xsd:restriction base="xsd:string">
 *     &lt;!-- peer -->
 *     &lt;xsd:enumeration value="0"/>
 *     &lt;!-- group -->
 *     &lt;xsd:enumeration value="1"/>
 *     &lt;!-- adv -->
 *     &lt;xsd:enumeration value="2"/>
 *   &lt;/xsd:restriction>
 * &lt;/xsd:simpleType>
 *
 * &lt;xs:complexType name="DiscoveryQuery">
 *   &lt;xs:sequence>
 *     &lt;xs:element name="Type" type="jxta:DiscoveryQueryType"/>
 *     &lt;xs:element name="Threshold" type="xs:unsignedInt" minOccurs="0"/>
 *     &lt;xs:element name="Attr" type="xs:string" minOccurs="0"/>
 *     &lt;xs:element name="Value" type="xs:string" minOccurs="0"/>
 *     &lt;!-- The following should refer to a peer adv, but is instead a whole doc for historical reasons -->
 *     &lt;xs:element name="PeerAdv" type="xs:string" minOccurs="0"/>
 *   &lt;/xs:sequence>
 * &lt;/xs:complexType>
 * </pre>
 *
 * @see net.jxta.discovery.DiscoveryService
 * @see net.jxta.impl.discovery.DiscoveryServiceImpl
 * @see <a href="http://spec.jxta.org/nonav/v1.0/docbook/JXTAProtocols.html#proto-pdp" target="_blank">JXTA Protocols Specification : Peer Discovery Protocol</a>
 */
public class DiscoveryQuery extends DiscoveryQueryMsg {

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

    private static final String typeTag = "Type";
    private static final String peerAdvTag = "PeerAdv";
    private static final String thresholdTag = "Threshold";
    private static final String queryAttrTag = "Attr";
    private static final String queryValueTag = "Value";

    /**
     *  Default constructor
     */
    public DiscoveryQuery() {}

    /**
     * Construct from a StructuredDocument
     *
     */
    public DiscoveryQuery(Element doc) {
        initialize(doc);
    }

    /**
     *  Process an individual element from the document during parse. Normally,
     *  implementations will allow the base advertisments a chance to handle the
     *  element before attempting ot handle the element themselves. ie.
     *
     *  <p/><pre><code>
     *  protected boolean handleElement(Element elem) {
     *
     *      if (super.handleElement()) {
     *           // it's been handled.
     *           return true;
     *           }
     *
     *      <i>... handle elements here ...</i>
     *
     *      // we don't know how to handle the element
     *      return false;
     *      }
     *  </code></pre>
     *
     *  @param raw the element to be processed.
     *  @return true if the element was recognized, otherwise false.
     */
    protected boolean handleElement(Element raw) {

        XMLElement elem = (XMLElement) raw;

        if(elem.getName().equals(typeTag)) {
            setDiscoveryType(Integer.parseInt(elem.getTextValue()));
            return true;
        }
        if(elem.getName().equals(thresholdTag)) {
            setThreshold(Integer.parseInt(elem.getTextValue()));
            return true;
        }
        if(elem.getName().equals(peerAdvTag)) {
            setPeerAdv(elem.getTextValue());
            return true;
        }
        if(elem.getName().equals(queryAttrTag)) {
            setAttr(elem.getTextValue());
            return true;
        }
        if(elem.getName().equals(queryValueTag)) {
            setValue(elem.getTextValue());
            return true;
        }

        // element was not handled
        return false;
    }

    /**
     *  Intialize a Discovery Query from a portion of a structured document.
     *  @param root document to intialize from
     */
    protected void initialize(Element root) {

        if(!XMLElement.class.isInstance(root))
            throw new IllegalArgumentException(getClass().getName() + " only supports XMLElement");

        XMLElement doc = (XMLElement) root;

        if (! doc.getName().equals(getAdvertisementType()))
            throw new IllegalArgumentException("Could not construct : "
                                               + getClass().getName() + "from doc containing a " + doc.getName());

        setDiscoveryType(-1); // force illegal value;

        Enumeration elements = doc.getChildren();
        while (elements.hasMoreElements()) {
            Element elem = (Element) elements.nextElement();

            if(!handleElement(elem)) {
                if (LOG.isEnabledFor(Level.DEBUG)) {
                    LOG.debug("Unhandled Element : " + elem.toString());
                }
            };
        }

        // sanity check time!

        if((DiscoveryService.PEER != getDiscoveryType()) && (DiscoveryService.GROUP != getDiscoveryType()) && (DiscoveryService.ADV != getDiscoveryType())) {
            throw new IllegalArgumentException("Type is not one of the required values.");
        }
        if(getThreshold() < 0) {
            throw new IllegalArgumentException("Threshold must not be less than zero.");
        }
        if((getDiscoveryType() != DiscoveryService.PEER) && (getThreshold() == 0)) {
            throw new IllegalArgumentException("Threshold may not be zero.");
        }
        if((null == getAttr()) && (null != getValue())) {
            throw new IllegalArgumentException("Value specified without attribute.");
        }
    }

    /**
     *  {@inheritDoc}
     */
    public Document getDocument(MimeMediaType asMimeType) {
        StructuredDocument adv = (StructuredTextDocument)
                                 StructuredDocumentFactory.newStructuredDocument(asMimeType, getAdvertisementType());

        if(adv instanceof XMLDocument) {
            XMLDocument xmlDoc = (XMLDocument) adv;
            xmlDoc.addAttribute("xmlns:jxta", "http://jxta.org");
            xmlDoc.addAttribute("xml:space", "preserve");
        }

        Element e;
        e = adv.createElement(typeTag, Integer.toString(getDiscoveryType()));
        adv.appendChild(e);

        int threshold = getThreshold();
        if(threshold < 0) {
            throw new IllegalStateException("threshold must be >= 0");
        }
        e = adv.createElement(thresholdTag, Integer.toString(threshold));
        adv.appendChild(e);

        PeerAdvertisement peerAdv = getPeerAdvertisement();
        if((peerAdv != null) ) {
            e = adv.createElement(peerAdvTag, peerAdv.toString());
            adv.appendChild(e);
        }

        String attr = getAttr();
        if((attr != null) && (attr.length() > 0)) {
            e = adv.createElement(queryAttrTag, attr.trim());
            adv.appendChild(e);

            String value = getValue();
            if((value != null) && (value.length() > 0)) {
                e = adv.createElement(queryValueTag, value.trim());
                adv.appendChild(e);
            } else {
                if(threshold < 0)
                    throw new IllegalStateException("Attribute specified, but no value was specified.");
            }
        }
        return adv;
    }

    /**
     * return the string representaion of this doc
     *
     *  @deprecated should not be used. use getDocument().toString() instead.
     */
    public String toString() {

        try {
            StructuredTextDocument doc = (StructuredTextDocument) getDocument(MimeMediaType.XMLUTF8);

            return doc.toString();
        } catch(Throwable e) {
            if(e instanceof Error) {
                throw (Error) e;
            } else
                if(e instanceof RuntimeException) {
                    throw (RuntimeException) e;
                } else {
                    throw new UndeclaredThrowableException(e);
                }
        }
    }
}