advertisementfactory.java

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

/*
 * 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
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 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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 * 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: AdvertisementFactory.java,v 1.35 2005/06/17 02:18:49 bondolo Exp $
 */

package net.jxta.document;

import java.io.InputStream;
import java.io.Reader;
import java.util.HashMap;
import java.util.Map;

import java.io.IOException;
import java.util.NoSuchElementException;
import java.util.MissingResourceException;

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

import net.jxta.util.ClassFactory;

/**
 * A Factory class for Advertisements. This class abstracts the
 * the implementations used to represent and create advertisements.
 *
 * <p/>Advertisements are core objects that are used to advertise a Peer, a
 * PeerGroup, a Service, or a PipeServiceImpl. The Advertisement class provides
 * a platform independent representation of core objects that can be exchanged
 * between different implementations (Java, C).
 *
 * <p/>The AdvertisementFactory extends the ClassFactory to register the various
 * types of adverstisements into a static hastable. The factory is called with
 * the Advertisement type requested to create the corresponding advertisement
 * type.
 *
 * <p/>The initial set of Advertisement instances is loaded from the java
 * property "net.jxta.impl.config.AdvertisementInstanceTypes"
 *
 * <p/>It would be nice to have "newAdvertisement" methods for "Document" and
 * "TextDocument", but this is not feasible because "TextElement" got there
 *  first.
 *
 * @see net.jxta.document.Advertisement
 * @see net.jxta.document.Document
 * @see net.jxta.document.MimeMediaType
 * @see net.jxta.peergroup.PeerGroup
 * @see net.jxta.protocol.PeerAdvertisement
 * @see net.jxta.protocol.PeerGroupAdvertisement
 * @see net.jxta.protocol.PipeAdvertisement
 **/
public class AdvertisementFactory extends ClassFactory {
    /**
     *  Log4J categorgy
     **/
    private static final Logger LOG = Logger.getLogger( AdvertisementFactory.class.getName());
    
    /**
     *  Interface for instantiators of Advertisements
     **/
    public interface Instantiator {
        
        /**
         * Returns the identifying type of this Advertisement.
         *
         * @return String the type of advertisement
         **/
        String getAdvertisementType( );
        
        /**
         * Constructs an instance of {@link Advertisement} matching the type
         * specified by the <CODE>advertisementType</CODE> parameter.
         *
         *
         * @return The instance of {@link Advertisement}.
         **/
        Advertisement newInstance( );
        
        /**
         * Constructs an instance of {@link Advertisement} matching the type
         * specified by the <CODE>advertisementType</CODE> parameter.
         *
         * @param root Specifies a portion of a @link StructuredDocument} which
         * will be converted into an Advertisement.
         * @return The instance of {@link Advertisement}.
         **/
        Advertisement newInstance( net.jxta.document.Element root );
    }
    
    /**
     *  This class is a singleton. This is the instance that backs the
     *  static methods.
     **/
    private final static AdvertisementFactory factory = new AdvertisementFactory();
    
    /**
     *  This is the map of mime-types and constructors used by
     *  <CODE>newStructuredDocument</CODE>.
     **/
    private final Map  encodings = new HashMap();
    
    /**
     *  If true then the pre-defined set of StructuredDocument sub-classes has
     *  been registered from the property containing them.
     **/
    private boolean loadedProperty = false;
    
    /**
     *  Private constructor. This class is not meant to be instantiated except
     *  by itself.
     *
     **/
    private AdvertisementFactory() {}
    
    /**
     *  Registers the pre-defined set of StructuredDocument sub-classes so that
     *  this factory can construct them.
     *
     *
     *  @return true if at least one of the StructuredDocument sub-classes could
     *  be registered otherwise false.
     **/
    private boolean doLoadProperty() {
        try {
            return registerFromResources( "net.jxta.impl.config", "AdvertisementInstanceTypes" );
        } catch ( MissingResourceException notFound ) {
            if (LOG.isEnabledFor(Level.FATAL)) {
                LOG.fatal( "Could not find net.jxta.impl.config properties file!" );
            }
            return false;
        }
    }
    
    /**
     *  {@inheritDoc}
     **/
    protected Map getAssocTable() {
        return encodings;
    }
    
    /**
     *  {@inheritDoc}
     **/
    public Class getClassOfInstantiators() {
        // our key is the doctype names.
        return Instantiator.class;
    }
    
    /**
     *  {@inheritDoc}
     **/
    public Class getClassForKey() {
        // our key is the doctype names.
        return java.lang.String.class;
    }
    
    /**
     *  {@inheritDoc}
     **/
    protected boolean registerAssoc( String className ) {
        boolean registeredSomething = false;
        
        try {
            Class advClass = Class.forName( className + "$Instantiator" );
            
            Instantiator instantiator = (Instantiator) advClass.newInstance();
            
            String advType = instantiator.getAdvertisementType( );
            
            registeredSomething = registerAdvertisementInstance( advType, instantiator );
        } catch( Exception all ) {
            if (LOG.isEnabledFor(Level.DEBUG)) {
                LOG.debug( "Failed to register '" + className + "'", all );
            }
        }
        
        return registeredSomething;
    }
    
    /**
     *  Register an instantiator for and advertisement type to allow instances
     *  of that type to be created.
     *
     *  @param rootType  the identifying value for this advertisement instance
     *   type
     *  @param instantiator   the instantiator to use in constructing objects
     *   of this rootType.
     *  @return boolean  true if the rootType type is registered. If there is
     *   already a constructor for this type then false will be returned.
     **/
    public static boolean registerAdvertisementInstance( String rootType, Instantiator instantiator ) {
        boolean result = factory.registerAssoc( rootType, instantiator );
        
        return result;
    }
    
    /**
     * Constructs a new instance of {@link Advertisement} matching the type
     * specified by the <CODE>advertisementType</CODE> parameter.
     *
     * @param advertisementType Specifies the type of advertisement to create.
     * @return The instance of {@link Advertisement}.
     * @throws NoSuchElementException if there is no matching advertisement type.
     **/
    public static Advertisement newAdvertisement( String advertisementType ) {
        if( ! factory.loadedProperty ) {
            factory.loadedProperty = factory.doLoadProperty();
        }
        
        Instantiator instantiator =
        (Instantiator) factory.getInstantiator( advertisementType );
        
        Advertisement a = instantiator.newInstance( );
        
        return a;
    }
    
    /**
     * Constructs an instance of {@link Advertisement} from the provided
     * <code>InputStream</code>. The content type of the stream is declared via
     * the <code>mimetype</code> parameter.
     *
     * @deprecated Please convert your code to construct an XML document using
     * StructuredDocumentFactory before calling AdvertisementFactory.
     *
     * @param mimetype Specifies the mime media type of the stream being read.
     * @param stream imput stream used to read data to construct the advertisement
     * @return The instance of {@link Advertisement}
     * @throws IOException error reading message from input stream
     * @throws NoSuchElementException if there is no matching advertisement type
     * for the type of document read in.
     * @throws UnsupportedOperationException if the specified mime type is not
     *  associated with a text oriented document type.
     **/
    public static Advertisement newAdvertisement( MimeMediaType mimetype, InputStream stream )
    throws IOException {
        
        StructuredTextDocument doc = (StructuredTextDocument)
        StructuredDocumentFactory.newStructuredDocument( mimetype, stream );
        
        return newAdvertisement( (TextElement) doc );
    }
    
    /**
     * Reconstructs an instance of {@link Advertisement} from the provided
     * <code>Reader</code>. The content type of the reader is declared via the
     * <code>mimetype</code> parameter.
     *
     * @deprecated Please convert your code to construct an XML document using
     * StructuredDocumentFactory before calling AdvertisementFactory.
     *
     * @param mimetype Specifies the mime media type of the stream being read.
     * @param source used to read data to construct the advertisement.
     * @return The instance of {@link Advertisement}
     * @throws IOException error reading message from input stream
     * @throws NoSuchElementException if there is no matching advertisement type
     * for the type of document read in.
     * @throws UnsupportedOperationException if the specified mime type is not
     *  associated with a text oriented document type.
     **/
    public static Advertisement newAdvertisement( MimeMediaType mimetype, Reader source )
    throws IOException {
        StructuredTextDocument doc = (StructuredTextDocument)
        StructuredDocumentFactory.newStructuredDocument( mimetype, source );
        
        return newAdvertisement( (TextElement) doc );
    }
    
    /**
     * Reconstructs an instance of {@link Advertisement} matching the type
     * specified by the <CODE>root</CODE> parameter.
     *
     * @deprecated Advertisements must be encoded in XML. This is a legacy
     * static constructor. You should convert your code to use the 
     * {@link net.jxta.document.XMLElement} version.
     *
     * @param root Specifies a portion of a StructuredDocument which will be
     * converted into an Advertisement.
     * @return The instance of {@link Advertisement}.
     * @throws NoSuchElementException if there is no advertisement type
     * matching the type of the root node.
     **/
    public static Advertisement newAdvertisement( TextElement root ) {
        if( !(root instanceof XMLElement)) {
            throw new IllegalArgumentException( "Advertisements must be XML" );
        }
        
        return newAdvertisement( (XMLElement) root );
    }

    /**
     * Reconstructs an instance of {@link Advertisement} matching the type
     * specified by the <CODE>root</CODE> parameter.
     *
     * @param root Specifies a portion of a StructuredDocument which will be
     * converted into an Advertisement.
     * @return The instance of {@link Advertisement}.
     * @throws NoSuchElementException if there is no advertisement type
     * matching the type of the root node.
     **/
    public static Advertisement newAdvertisement( XMLElement root ) {
        if( ! factory.loadedProperty ) {
            factory.loadedProperty = factory.doLoadProperty();
        }
        
        Instantiator instantiator = null;
        
        // The base type of the advertisement may be overridden by a type
        // declaration. If this is the case, then we try to use that as the
        // key rather than the root name.
        if( root instanceof Attributable ) {
            Attribute type = ((Attributable)root).getAttribute( "type" );
            
            if( null != type ) {
                try {
                    instantiator = (Instantiator) factory.getInstantiator( type.getValue() );
                } catch( NoSuchElementException notThere ) {
                    // do nothing, its not fatal
                    ;
                }
            }
        }
        
        // Don't have an instantiator for the type attribute, try the root name
        if( null == instantiator ) {
            instantiator = (Instantiator) factory.getInstantiator( root.getName() );
        }
        
        Advertisement a = instantiator.newInstance( root );
        
        return a;
    }
}