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Glassfish example source code file (ClassLoaderHierarchy.java)

This example Glassfish source code file (ClassLoaderHierarchy.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Glassfish tags/keywords

classloader, classloader, classloaderhierarchy, contract, contract, delegatingclassloader, delegatingclassloader, deploymentcontext, list, malformedurlexception, malformedurlexception, net, network, resolveerror, string, util

The Glassfish ClassLoaderHierarchy.java source code

/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 *
 * Copyright (c) 2007-2010 Oracle and/or its affiliates. All rights reserved.
 *
 * The contents of this file are subject to the terms of either the GNU
 * General Public License Version 2 only ("GPL") or the Common Development
 * and Distribution License("CDDL") (collectively, the "License").  You
 * may not use this file except in compliance with the License.  You can
 * obtain a copy of the License at
 * https://glassfish.dev.java.net/public/CDDL+GPL_1_1.html
 * or packager/legal/LICENSE.txt.  See the License for the specific
 * language governing permissions and limitations under the License.
 *
 * When distributing the software, include this License Header Notice in each
 * file and include the License file at packager/legal/LICENSE.txt.
 *
 * GPL Classpath Exception:
 * Oracle designates this particular file as subject to the "Classpath"
 * exception as provided by Oracle in the GPL Version 2 section of the License
 * file that accompanied this code.
 *
 * Modifications:
 * If applicable, add the following below the License Header, with the fields
 * enclosed by brackets [] replaced by your own identifying information:
 * "Portions Copyright [year] [name of copyright owner]"
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 * If you wish your version of this file to be governed by only the CDDL or
 * only the GPL Version 2, indicate your decision by adding "[Contributor]
 * elects to include this software in this distribution under the [CDDL or GPL
 * Version 2] license."  If you don't indicate a single choice of license, a
 * recipient has the option to distribute your version of this file under
 * either the CDDL, the GPL Version 2 or to extend the choice of license to
 * its licensees as provided above.  However, if you add GPL Version 2 code
 * and therefore, elected the GPL Version 2 license, then the option applies
 * only if the new code is made subject to such option by the copyright
 * holder.
 */

package org.glassfish.internal.api;

import org.glassfish.internal.api.DelegatingClassLoader;
import org.glassfish.api.deployment.DeploymentContext;
import org.jvnet.hk2.annotations.Contract;

import java.net.URI;
import java.net.MalformedURLException;
import java.util.List;

import com.sun.enterprise.module.ResolveError;

/**
 * This class is responsible foe creation of class loader hierarchy
 * of an application.
 *
 * @author Sanjeeb.Sahoo@Sun.COM
 */
@Contract
public interface ClassLoaderHierarchy {
    /**
     * Returns a ClassLoader that can load classes exported by any OSGi bundle
     * in the system for public use. Such classes include Java EE API, AMX API,
     * appserv-ext API, etc. CommonClassLoader delegates to this class loader.
     * @return a ClassLoader that can load classes exported by any bundles
     */
    ClassLoader getAPIClassLoader();

    /**
     * Returns a class loader that is common to all deployed applications.
     * Common Class Loader is responsible for loading classes from
     * following URLs (the order is strictly maintained):
     * lib/*.jar:domain_dir/lib/classes:domain_dir/lib/*.jar.
     * Please note that domain_dir/lib/classes comes before domain_dir/lib/*.jar,
     * just like WEB-INF/classes is searched first before WEB-INF/lib/*.jar.
     * It delegates to APIClassLoader.
     * @see #getAPIClassLoader()
     * @return ClassLoader common to all deployed applications.
     */
    ClassLoader getCommonClassLoader();

    /**
     * Returns the classpath equiavalent to what is used by classloader
     * returned by {@link #getCommonClassLoader()}. Classpath entries are
     * separated by {@link java.io.File#separatorChar}, but don't assume
     * there will be any leading or trailing separator char. It returns
     * an empty string if there are no libraries installed.
     * @return ClassPath separated by {@link java.io.File#pathSeparatorChar}
     */
    String getCommonClassPath();

    /**
     * Returns the class loader which has visibility to appropriate list of
     * standalone RARs deployed in the server. Depending on a policy,
     * this can either return a singleton classloader for all applications or
     * a class loader specific to an application. When a singleton class loader
     * is returned, such a class loader will have visibility to all the
     * standalone RARs deployed in the system. When a class loader specific
     * to an application is returned, such a class loader will have visibility
     * to only standalone RARs that the application depends on.
     *
     * @param application Application whose class loader hierarchy is being set
     * @return class loader which has visibility to appropriate list of
     *         standalone RARs.
     */
    DelegatingClassLoader getConnectorClassLoader(String application);

    /**
     * Returns AppLibClassLoader. As the name suggests, this class loader
     * has visibility to deploy time libraries (--libraries and EXTENSION_LIST of MANIFEST.MF, provided the library is
     * available in 'applibs' directory) for an application.
     * It is different from CommonClassLoader in a sense that the libraries that
     * are part of common class loader are shared by all applications,
     * where as this class loader adds a scope to a library.
     * @param application Application for which this class loader is created
     * @param libURIs list of URIs, where each URI represent a library
     * @return class loader that has visibility to appropriate
     * application specific libraries.
     * @throws MalformedURLException
     * @see #getAppLibClassFinder(List<URI>)
     */
    ClassLoader getAppLibClassLoader(String application, List<URI> libURIs)
            throws MalformedURLException;

    /**
     * Returns ApplibClassFinder. As the name suggests, this class finder
     * has visibility to deploy time libraries (--libraries and EXTENSION_LIST of MANIFEST.MF,
     * provided the library is available in 'applibs' directory) for an application.
     * It is different from CommonClassLoader in a sense that the libraries that
     * are part of common class loader are shared by all applications,
     * where as this class loader adds a scope to a library.    <br>
     * <b>NOTE : Difference between this API and getAppLibClassLoader(String, List<URI>) is the latter
     * will be used by all applications (for its parent classloader) whereas this API will be used only by connector
     * classloader. All other application classloaders will have AppLibClassLoader as parent where as connector classloader
     * will be above AppLibClassLoader and hence simple delegation is not feasible.
     * @param libURIs list of URIs, where each URI represent a library
     * @return class loader that has visibility to appropriate
     * application specific libraries.
     * @throws MalformedURLException
     * @see #getAppLibClassLoader(String, List<URI>)
     */
    DelegatingClassLoader.ClassFinder getAppLibClassFinder(List<URI> libURIs)
            throws MalformedURLException;


    /**
        * Sets up the parent class loader for the application class loader.
        * Application class loader are under the control of the ArchiveHandler since
        * a special archive file format will require a specific class loader.
        *
        * However GlassFish needs to be able to add capabilities to the application
        * like adding APIs accessibility, this is done through its parent class loader
        * which we create and maintain.
        *
        * @param parent the parent class loader
        * @param context deployment context
        * @return class loader capable of loading public APIs identified by the deployers
        * @throws com.sun.enterprise.module.ResolveError if one of the deployer's public API module is not found.
        */
       public ClassLoader createApplicationParentCL(ClassLoader parent, DeploymentContext context)
           throws ResolveError;

}

Other Glassfish examples (source code examples)

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