jxtaloader.java

JXTA&#8482 is a set of open, generalized peer-to-peer (P2P) protocols that allow any networked devi

/*
 * Copyright (c) 2001-2007 Sun Microsystems, Inc.  All rights reserved.
 *  
 *  The Sun Project JXTA(TM) Software License
 *  
 *  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 Sun Microsystems, Inc. for JXTA(TM) technology." 
 *     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.
 *  
 *  JXTA is a registered trademark of Sun Microsystems, Inc. in the United 
 *  States and other countries.
 *  
 *  Please see the license information page at :
 *  <http://www.jxta.org/project/www/license.html> for instructions on use of 
 *  the license in source files.
 *  
 *  ====================================================================
 *  
 *  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. 
 */

package net.jxta.platform;


import java.net.URL;
import java.net.URLClassLoader;

import net.jxta.protocol.ModuleImplAdvertisement;


/**
 * A ClassLoader which provides additional JXTA functionality. You can load
 * classes by ModuleSpecID. Classes are defined with ModuleImplAdvertisements
 * and class loading will determine suitability using the provided
 * compatibility statements.
 */
public abstract class JxtaLoader extends URLClassLoader {
    
    /**
     *  Construct a new loader with the specified parent loader and
     *
     *  @param parent  the parent class loader for delegation.
     */
    public JxtaLoader(ClassLoader parent) {
        this(new URL[0], parent);
    }
    
    /**
     * Construct a new loader for the specified URLS with the specified parent
     * loader.
     *
     *  @param urls  the URLs from which to load classes and resources.
     *  @param parent  the parent class loader for delegation.
     */
    public JxtaLoader(URL[] urls, ClassLoader parent) {
        super(urls, parent);
    }
    
    /**
     *  {@inheritDoc}
     */
    @Override
    public void addURL(URL url) {
        super.addURL(url);
    }
    
    /**
     * Finds and loads the class with the specified spec ID from the URL search
     * path. Any URLs referring to JAR files are loaded and opened as needed
     * until the class is found.
     *
     *  @param spec the specid of the class to load.
     *  @throws ClassNotFoundException if the class could not be found.
     *  @return the resulting class.
     */
    public abstract Class<? extends Module> findClass(ModuleSpecID spec) throws ClassNotFoundException;
    
    /**
     *  Loads the class with the specified spec ID from the URL search
     *  path.
     *
     *  @param spec the specid of the class to load.
     *  @throws ClassNotFoundException if the class could not be found.
     *  @return the resulting class.
     */
    public abstract Class<? extends Module> loadClass(ModuleSpecID spec) throws ClassNotFoundException;
    
    /**
     *  Defines a new class from a Module Impl Advertisement.
     *
     *  @param impl The moduleImplAdvertisement containing the class 
     *  specification
     *  @return The Class object that was created from the specified class data.
     */
    public abstract Class<? extends Module> defineClass(ModuleImplAdvertisement impl);

    /**
     *  Finds the ModuleImplAdvertisement for the associated class in the
     *  context of this ClassLoader.
     *
     *  @param clazz The class who's ModuleImplAdvertisement is desired.
     *  @return The matching {@code ModuleImplAdvertisement} otherwise
     *  {@code null} if there is no known association.
     */
    public abstract ModuleImplAdvertisement findModuleImplAdvertisement(Class<? extends Module> clazz);

    /**
     *  Finds the ModuleImplAdvertisement for the associated class in the 
     *  context of this ClassLoader.
     *
     *  @param msid The module spec id who's ModuleImplAdvertisement is desired.
     *  @return The matching {@code ModuleImplAdvertisement} otherwise
     *  {@code null} if there is no known association.
     */
    public abstract ModuleImplAdvertisement findModuleImplAdvertisement(ModuleSpecID msid);
}