Java example source code file (RMIClassLoaderSpi.java)

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

Learn more about this Java project at its project page.

Java - Java tags/keywords

class, classloader, classnotfoundexception, malformedurlexception, net, network, rmiclassloaderspi, securityexception, string

The RMIClassLoaderSpi.java Java example source code

/*
 * Copyright (c) 2000, 2006, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

package java.rmi.server;

import java.net.MalformedURLException;
import java.net.URL;

/**
 * <code>RMIClassLoaderSpi is the service provider interface for
 * <code>RMIClassLoader.
 *
 * In particular, an <code>RMIClassLoaderSpi instance provides an
 * implementation of the following static methods of
 * <code>RMIClassLoader:
 *
 * <ul>
 *
 * <li>{@link RMIClassLoader#loadClass(URL,String)}
 * <li>{@link RMIClassLoader#loadClass(String,String)}
 * <li>{@link RMIClassLoader#loadClass(String,String,ClassLoader)}
 * <li>{@link RMIClassLoader#loadProxyClass(String,String[],ClassLoader)}
 * <li>{@link RMIClassLoader#getClassLoader(String)}
 * <li>{@link RMIClassLoader#getClassAnnotation(Class)}
 *
 * </ul>
 *
 * When one of those methods is invoked, its behavior is to delegate
 * to a corresponding method on an instance of this class.
 * The details of how each method delegates to the provider instance is
 * described in the documentation for each particular method.
 * See the documentation for {@link RMIClassLoader} for a description
 * of how a provider instance is chosen.
 *
 * @author      Peter Jones
 * @author      Laird Dornin
 * @see         RMIClassLoader
 * @since       1.4
 */
public abstract class RMIClassLoaderSpi {

    /**
     * Provides the implementation for
     * {@link RMIClassLoader#loadClass(URL,String)},
     * {@link RMIClassLoader#loadClass(String,String)}, and
     * {@link RMIClassLoader#loadClass(String,String,ClassLoader)}.
     *
     * Loads a class from a codebase URL path, optionally using the
     * supplied loader.
     *
     * Typically, a provider implementation will attempt to
     * resolve the named class using the given <code>defaultLoader,
     * if specified, before attempting to resolve the class from the
     * codebase URL path.
     *
     * <p>An implementation of this method must either return a class
     * with the given name or throw an exception.
     *
     * @param   codebase the list of URLs (separated by spaces) to load
     * the class from, or <code>null
     *
     * @param   name the name of the class to load
     *
     * @param   defaultLoader additional contextual class loader
     * to use, or <code>null
     *
     * @return  the <code>Class object representing the loaded class
     *
     * @throws  MalformedURLException if <code>codebase is
     * non-<code>null and contains an invalid URL, or
     * if <code>codebase is null and a provider-specific
     * URL used to load classes is invalid
     *
     * @throws  ClassNotFoundException if a definition for the class
     * could not be found at the specified location
     */
    public abstract Class<?> loadClass(String codebase, String name,
                                       ClassLoader defaultLoader)
        throws MalformedURLException, ClassNotFoundException;

    /**
     * Provides the implementation for
     * {@link RMIClassLoader#loadProxyClass(String,String[],ClassLoader)}.
     *
     * Loads a dynamic proxy class (see {@link java.lang.reflect.Proxy}
     * that implements a set of interfaces with the given names
     * from a codebase URL path, optionally using the supplied loader.
     *
     * <p>An implementation of this method must either return a proxy
     * class that implements the named interfaces or throw an exception.
     *
     * @param   codebase the list of URLs (space-separated) to load
     * classes from, or <code>null
     *
     * @param   interfaces the names of the interfaces for the proxy class
     * to implement
     *
     * @return  a dynamic proxy class that implements the named interfaces
     *
     * @param   defaultLoader additional contextual class loader
     * to use, or <code>null
     *
     * @throws  MalformedURLException if <code>codebase is
     * non-<code>null and contains an invalid URL, or
     * if <code>codebase is null and a provider-specific
     * URL used to load classes is invalid
     *
     * @throws  ClassNotFoundException if a definition for one of
     * the named interfaces could not be found at the specified location,
     * or if creation of the dynamic proxy class failed (such as if
     * {@link java.lang.reflect.Proxy#getProxyClass(ClassLoader,Class[])}
     * would throw an <code>IllegalArgumentException for the given
     * interface list)
     */
    public abstract Class<?> loadProxyClass(String codebase,
                                            String[] interfaces,
                                            ClassLoader defaultLoader)
        throws MalformedURLException, ClassNotFoundException;

    /**
     * Provides the implementation for
     * {@link RMIClassLoader#getClassLoader(String)}.
     *
     * Returns a class loader that loads classes from the given codebase
     * URL path.
     *
     * <p>If there is a security manger, its checkPermission
     * method will be invoked with a
     * <code>RuntimePermission("getClassLoader") permission;
     * this could result in a <code>SecurityException.
     * The implementation of this method may also perform further security
     * checks to verify that the calling context has permission to connect
     * to all of the URLs in the codebase URL path.
     *
     * @param   codebase the list of URLs (space-separated) from which
     * the returned class loader will load classes from, or <code>null
     *
     * @return a class loader that loads classes from the given codebase URL
     * path
     *
     * @throws  MalformedURLException if <code>codebase is
     * non-<code>null and contains an invalid URL, or
     * if <code>codebase is null and a provider-specific
     * URL used to identify the class loader is invalid
     *
     * @throws  SecurityException if there is a security manager and the
     * invocation of its <code>checkPermission method fails, or
     * if the caller does not have permission to connect to all of the
     * URLs in the codebase URL path
     */
    public abstract ClassLoader getClassLoader(String codebase)
        throws MalformedURLException; // SecurityException

    /**
     * Provides the implementation for
     * {@link RMIClassLoader#getClassAnnotation(Class)}.
     *
     * Returns the annotation string (representing a location for
     * the class definition) that RMI will use to annotate the class
     * descriptor when marshalling objects of the given class.
     *
     * @param   cl the class to obtain the annotation for
     *
     * @return  a string to be used to annotate the given class when
     * it gets marshalled, or <code>null
     *
     * @throws  NullPointerException if <code>cl is null
     */
    public abstract String getClassAnnotation(Class<?> cl);
}