1/*
2 * Copyright (c) 2000, 2006, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.  Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
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19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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24 */
25
26package java.rmi.server;
27
28import java.net.MalformedURLException;
29import java.net.URL;
30
31/**
32 * <code>RMIClassLoaderSpi</code> is the service provider interface for
33 * <code>RMIClassLoader</code>.
34 *
35 * In particular, an <code>RMIClassLoaderSpi</code> instance provides an
36 * implementation of the following static methods of
37 * <code>RMIClassLoader</code>:
38 *
39 * <ul>
40 *
41 * <li>{@link RMIClassLoader#loadClass(URL,String)}
42 * <li>{@link RMIClassLoader#loadClass(String,String)}
43 * <li>{@link RMIClassLoader#loadClass(String,String,ClassLoader)}
44 * <li>{@link RMIClassLoader#loadProxyClass(String,String[],ClassLoader)}
45 * <li>{@link RMIClassLoader#getClassLoader(String)}
46 * <li>{@link RMIClassLoader#getClassAnnotation(Class)}
47 *
48 * </ul>
49 *
50 * When one of those methods is invoked, its behavior is to delegate
51 * to a corresponding method on an instance of this class.
52 * The details of how each method delegates to the provider instance is
53 * described in the documentation for each particular method.
54 * See the documentation for {@link RMIClassLoader} for a description
55 * of how a provider instance is chosen.
56 *
57 * @author      Peter Jones
58 * @author      Laird Dornin
59 * @see         RMIClassLoader
60 * @since       1.4
61 */
62public abstract class RMIClassLoaderSpi {
63
64    /**
65     * Provides the implementation for
66     * {@link RMIClassLoader#loadClass(URL,String)},
67     * {@link RMIClassLoader#loadClass(String,String)}, and
68     * {@link RMIClassLoader#loadClass(String,String,ClassLoader)}.
69     *
70     * Loads a class from a codebase URL path, optionally using the
71     * supplied loader.
72     *
73     * Typically, a provider implementation will attempt to
74     * resolve the named class using the given <code>defaultLoader</code>,
75     * if specified, before attempting to resolve the class from the
76     * codebase URL path.
77     *
78     * <p>An implementation of this method must either return a class
79     * with the given name or throw an exception.
80     *
81     * @param   codebase the list of URLs (separated by spaces) to load
82     * the class from, or <code>null</code>
83     *
84     * @param   name the name of the class to load
85     *
86     * @param   defaultLoader additional contextual class loader
87     * to use, or <code>null</code>
88     *
89     * @return  the <code>Class</code> object representing the loaded class
90     *
91     * @throws  MalformedURLException if <code>codebase</code> is
92     * non-<code>null</code> and contains an invalid URL, or
93     * if <code>codebase</code> is <code>null</code> and a provider-specific
94     * URL used to load classes is invalid
95     *
96     * @throws  ClassNotFoundException if a definition for the class
97     * could not be found at the specified location
98     */
99    public abstract Class<?> loadClass(String codebase, String name,
100                                       ClassLoader defaultLoader)
101        throws MalformedURLException, ClassNotFoundException;
102
103    /**
104     * Provides the implementation for
105     * {@link RMIClassLoader#loadProxyClass(String,String[],ClassLoader)}.
106     *
107     * Loads a dynamic proxy class (see {@link java.lang.reflect.Proxy}
108     * that implements a set of interfaces with the given names
109     * from a codebase URL path, optionally using the supplied loader.
110     *
111     * <p>An implementation of this method must either return a proxy
112     * class that implements the named interfaces or throw an exception.
113     *
114     * @param   codebase the list of URLs (space-separated) to load
115     * classes from, or <code>null</code>
116     *
117     * @param   interfaces the names of the interfaces for the proxy class
118     * to implement
119     *
120     * @return  a dynamic proxy class that implements the named interfaces
121     *
122     * @param   defaultLoader additional contextual class loader
123     * to use, or <code>null</code>
124     *
125     * @throws  MalformedURLException if <code>codebase</code> is
126     * non-<code>null</code> and contains an invalid URL, or
127     * if <code>codebase</code> is <code>null</code> and a provider-specific
128     * URL used to load classes is invalid
129     *
130     * @throws  ClassNotFoundException if a definition for one of
131     * the named interfaces could not be found at the specified location,
132     * or if creation of the dynamic proxy class failed (such as if
133     * {@link java.lang.reflect.Proxy#getProxyClass(ClassLoader,Class[])}
134     * would throw an <code>IllegalArgumentException</code> for the given
135     * interface list)
136     */
137    public abstract Class<?> loadProxyClass(String codebase,
138                                            String[] interfaces,
139                                            ClassLoader defaultLoader)
140        throws MalformedURLException, ClassNotFoundException;
141
142    /**
143     * Provides the implementation for
144     * {@link RMIClassLoader#getClassLoader(String)}.
145     *
146     * Returns a class loader that loads classes from the given codebase
147     * URL path.
148     *
149     * <p>If there is a security manger, its <code>checkPermission</code>
150     * method will be invoked with a
151     * <code>RuntimePermission("getClassLoader")</code> permission;
152     * this could result in a <code>SecurityException</code>.
153     * The implementation of this method may also perform further security
154     * checks to verify that the calling context has permission to connect
155     * to all of the URLs in the codebase URL path.
156     *
157     * @param   codebase the list of URLs (space-separated) from which
158     * the returned class loader will load classes from, or <code>null</code>
159     *
160     * @return a class loader that loads classes from the given codebase URL
161     * path
162     *
163     * @throws  MalformedURLException if <code>codebase</code> is
164     * non-<code>null</code> and contains an invalid URL, or
165     * if <code>codebase</code> is <code>null</code> and a provider-specific
166     * URL used to identify the class loader is invalid
167     *
168     * @throws  SecurityException if there is a security manager and the
169     * invocation of its <code>checkPermission</code> method fails, or
170     * if the caller does not have permission to connect to all of the
171     * URLs in the codebase URL path
172     */
173    public abstract ClassLoader getClassLoader(String codebase)
174        throws MalformedURLException; // SecurityException
175
176    /**
177     * Provides the implementation for
178     * {@link RMIClassLoader#getClassAnnotation(Class)}.
179     *
180     * Returns the annotation string (representing a location for
181     * the class definition) that RMI will use to annotate the class
182     * descriptor when marshalling objects of the given class.
183     *
184     * @param   cl the class to obtain the annotation for
185     *
186     * @return  a string to be used to annotate the given class when
187     * it gets marshalled, or <code>null</code>
188     *
189     * @throws  NullPointerException if <code>cl</code> is <code>null</code>
190     */
191    public abstract String getClassAnnotation(Class<?> cl);
192}
193