RMIClassLoaderSpi


1   /*
2    * @(#)RMIClassLoaderSpi.java   1.14 04/05/05
3    *
4    * Copyright 2004 Sun Microsystems, Inc. All rights reserved.
5    * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
6    */
7   
8   package java.rmi.server;
9   
10  import java.net.MalformedURLException  ;
11  import java.net.URL  ;
12  
13  /**
14   * <code>RMIClassLoaderSpi</code> is the service provider interface for
15   * <code>RMIClassLoader</code>.
16   *
17   * In particular, an <code>RMIClassLoaderSpi</code> instance provides an
18   * implementation of the following static methods of
19   * <code>RMIClassLoader</code>:
20   *
21   * <ul>
22   *
23   * <li>{@link RMIClassLoader#loadClass(URL,String)}
24   * <li>{@link RMIClassLoader#loadClass(String,String)}
25   * <li>{@link RMIClassLoader#loadClass(String,String,ClassLoader)}
26   * <li>{@link RMIClassLoader#loadProxyClass(String,String[],ClassLoader)}
27   * <li>{@link RMIClassLoader#getClassLoader(String)}
28   * <li>{@link RMIClassLoader#getClassAnnotation(Class)}
29   *
30   * </ul>
31   *
32   * When one of those methods is invoked, its behavior is to delegate
33   * to a corresponding method on an instance of this class.
34   * The details of how each method delegates to the provider instance is
35   * described in the documentation for each particular method.
36   * See the documentation for {@link RMIClassLoader} for a description
37   * of how a provider instance is chosen.
38   *
39   * @version 1.14, 04/05/05
40   * @author  Peter Jones
41   * @author  Laird Dornin
42   * @see     RMIClassLoader
43   * @since   JDK1.4
44   */
45  public abstract class RMIClassLoaderSpi {
46  
47      /**
48       * Provides the implementation for
49       * {@link RMIClassLoader#loadClass(URL,String)},
50       * {@link RMIClassLoader#loadClass(String,String)}, and
51       * {@link RMIClassLoader#loadClass(String,String,ClassLoader)}.
52       *
53       * Loads a class from a codebase URL path, optionally using the
54       * supplied loader.
55       *
56       * Typically, a provider implementation will attempt to
57       * resolve the named class using the given <code>defaultLoader</code>,
58       * if specified, before attempting to resolve the class from the
59       * codebase URL path.
60       *
61       * <p>An implementation of this method must either return a class
62       * with the given name or throw an exception.
63       *
64       * @param   codebase the list of URLs (separated by spaces) to load
65       * the class from, or <code>null</code>
66       *
67       * @param   name the name of the class to load
68       *
69       * @param   defaultLoader additional contextual class loader
70       * to use, or <code>null</code>
71       *
72       * @return  the <code>Class</code> object representing the loaded class
73       *
74       * @throws  MalformedURLException if <code>codebase</code> is
75       * non-<code>null</code> and contains an invalid URL, or
76       * if <code>codebase</code> is <code>null</code> and a provider-specific
77       * URL used to load classes is invalid
78       *
79       * @throws  ClassNotFoundException if a definition for the class
80       * could not be found at the specified location
81       */
82      public abstract Class  <?> loadClass(String   codebase, String   name,
83                         ClassLoader   defaultLoader)
84      throws MalformedURLException  , ClassNotFoundException  ;
85      
86      /**
87       * Provides the implementation for
88       * {@link RMIClassLoader#loadProxyClass(String,String[],ClassLoader)}.
89       *
90       * Loads a dynamic proxy class (see {@link java.lang.reflect.Proxy}
91       * that implements a set of interfaces with the given names
92       * from a codebase URL path, optionally using the supplied loader.
93       * 
94       * <p>An implementation of this method must either return a proxy
95       * class that implements the named interfaces or throw an exception.
96       *
97       * @param   codebase the list of URLs (space-separated) to load
98       * classes from, or <code>null</code>
99       *
100      * @param   interfaces the names of the interfaces for the proxy class
101      * to implement
102      *
103      * @return  a dynamic proxy class that implements the named interfaces
104      *
105      * @param   defaultLoader additional contextual class loader
106      * to use, or <code>null</code>
107      *
108      * @throws  MalformedURLException if <code>codebase</code> is
109      * non-<code>null</code> and contains an invalid URL, or
110      * if <code>codebase</code> is <code>null</code> and a provider-specific
111      * URL used to load classes is invalid
112      *
113      * @throws  ClassNotFoundException if a definition for one of
114      * the named interfaces could not be found at the specified location,
115      * or if creation of the dynamic proxy class failed (such as if
116      * {@link java.lang.reflect.Proxy#getProxyClass(ClassLoader,Class[])}
117      * would throw an <code>IllegalArgumentException</code> for the given
118      * interface list)
119      */
120     public abstract Class  <?> loadProxyClass(String   codebase,
121                         String  [] interfaces,
122                         ClassLoader   defaultLoader)
123     throws MalformedURLException  , ClassNotFoundException  ;
124 
125     /**
126      * Provides the implementation for
127      * {@link RMIClassLoader#getClassLoader(String)}.
128      *
129      * Returns a class loader that loads classes from the given codebase
130      * URL path.
131      *
132      * <p>If there is a security manger, its <code>checkPermission</code>
133      * method will be invoked with a
134      * <code>RuntimePermission("getClassLoader")</code> permission;
135      * this could result in a <code>SecurityException</code>.
136      * The implementation of this method may also perform further security
137      * checks to verify that the calling context has permission to connect
138      * to all of the URLs in the codebase URL path.
139      *
140      * @param   codebase the list of URLs (space-separated) from which
141      * the returned class loader will load classes from, or <code>null</code>
142      *
143      * @return a class loader that loads classes from the given codebase URL
144      * path
145      *
146      * @throws  MalformedURLException if <code>codebase</code> is
147      * non-<code>null</code> and contains an invalid URL, or
148      * if <code>codebase</code> is <code>null</code> and a provider-specific
149      * URL used to identify the class loader is invalid
150      *
151      * @throws  SecurityException if there is a security manager and the
152      * invocation of its <code>checkPermission</code> method fails, or
153      * if the caller does not have permission to connect to all of the
154      * URLs in the codebase URL path
155      */
156     public abstract ClassLoader   getClassLoader(String   codebase)
157     throws MalformedURLException  ; // SecurityException
158 
159     /**
160      * Provides the implementation for
161      * {@link RMIClassLoader#getClassAnnotation(Class)}.
162      *
163      * Returns the annotation string (representing a location for
164      * the class definition) that RMI will use to annotate the class
165      * descriptor when marshalling objects of the given class.
166      *
167      * @param   cl the class to obtain the annotation for
168      *
169      * @return  a string to be used to annotate the given class when
170      * it gets marshalled, or <code>null</code>
171      *
172      * @throws  NullPointerException if <code>cl</code> is <code>null</code>
173      */
174     public abstract String   getClassAnnotation(Class  <?> cl);
175 }
176
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