001/* RMIClassLoader.java --
002   Copyright (c) 1996, 1997, 1998, 1999, 2002, 2003, 2004
003   Free Software Foundation, Inc.
004
005This file is part of GNU Classpath.
006
007GNU Classpath is free software; you can redistribute it and/or modify
008it under the terms of the GNU General Public License as published by
009the Free Software Foundation; either version 2, or (at your option)
010any later version.
011
012GNU Classpath is distributed in the hope that it will be useful, but
013WITHOUT ANY WARRANTY; without even the implied warranty of
014MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
015General Public License for more details.
016
017You should have received a copy of the GNU General Public License
018along with GNU Classpath; see the file COPYING.  If not, write to the
019Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
02002110-1301 USA.
021
022Linking this library statically or dynamically with other modules is
023making a combined work based on this library.  Thus, the terms and
024conditions of the GNU General Public License cover the whole
025combination.
026
027As a special exception, the copyright holders of this library give you
028permission to link this library with independent modules to produce an
029executable, regardless of the license terms of these independent
030modules, and to copy and distribute the resulting executable under
031terms of your choice, provided that you also meet, for each linked
032independent module, the terms and conditions of the license of that
033module.  An independent module is a module which is not derived from
034or based on this library.  If you modify this library, you may extend
035this exception to your version of the library, but you are not
036obligated to do so.  If you do not wish to do so, delete this
037exception statement from your version. */
038
039package java.rmi.server;
040
041import gnu.classpath.ServiceFactory;
042import gnu.classpath.SystemProperties;
043import gnu.java.rmi.server.RMIClassLoaderImpl;
044
045import java.net.MalformedURLException;
046import java.net.URL;
047import java.util.Iterator;
048
049/**
050 * This class provides a set of public static utility methods for supporting
051 * network-based class loading in RMI. These methods are called by RMI's
052 * internal marshal streams to implement the dynamic class loading of types for
053 * RMI parameters and return values.
054 * @since 1.1
055 */
056public class RMIClassLoader
057{
058  /**
059   * This class isn't intended to be instantiated.
060   */
061  private RMIClassLoader() {}
062
063  /**
064   * @deprecated
065   */
066  public static Class<?> loadClass(String name)
067    throws MalformedURLException, ClassNotFoundException
068  {
069    return loadClass("", name);
070  }
071
072  public static Class<?> loadClass(String codebase, String name)
073    throws MalformedURLException, ClassNotFoundException
074  {
075    RMIClassLoaderSpi spi = getProviderInstance();
076    if (spi == null)
077      spi = getDefaultProviderInstance(); 
078    return spi.loadClass(codebase, name, null);
079  }
080
081  public static Class<?> loadClass(String codebase, String name,
082                                   ClassLoader defaultLoader)
083    throws MalformedURLException, ClassNotFoundException
084  {
085    RMIClassLoaderSpi spi = getProviderInstance();
086    if (spi == null)
087      spi = getDefaultProviderInstance(); 
088    return spi.loadClass(codebase, name, defaultLoader);
089  }
090
091  public static Class<?> loadProxyClass (String codeBase, String[] interfaces,
092                                         ClassLoader defaultLoader)
093    throws MalformedURLException, ClassNotFoundException
094  {
095    RMIClassLoaderSpi spi = getProviderInstance();
096    if (spi == null)
097      spi = getDefaultProviderInstance();
098    return spi.loadProxyClass(codeBase, interfaces, defaultLoader);
099  }
100
101  /**
102   * Loads a class from <code>codeBase</code>.
103   *
104   * This method delegates to
105   * {@link RMIClassLoaderSpi#loadClass(String, String, ClassLoader)} and
106   * passes <code>codeBase.toString()</code> as first argument,
107   * <code>name</code> as second argument and <code>null</code> as third
108   * argument.
109   *
110   * @param codeBase the code base from which to load the class
111   * @param name the name of the class
112   *
113   * @return the loaded class
114   *
115   * @throws MalformedURLException if the URL is not well formed
116   * @throws ClassNotFoundException if the requested class cannot be found
117   */
118  public static Class<?> loadClass(URL codeBase, String name)
119    throws MalformedURLException, ClassNotFoundException
120  {
121    RMIClassLoaderSpi spi = getProviderInstance();
122    if (spi == null)
123      spi = getDefaultProviderInstance(); 
124    return spi.loadClass(codeBase.toString(), name, null);
125  }
126
127  /**
128   * Gets a classloader for the given codebase and with the current
129   * context classloader as parent.
130   * 
131   * @param codebase
132   * 
133   * @return a classloader for the given codebase
134   * 
135   * @throws MalformedURLException if the codebase contains a malformed URL
136   */
137  public static ClassLoader getClassLoader(String codebase) 
138    throws MalformedURLException
139  {
140    RMIClassLoaderSpi spi = getProviderInstance();
141    if (spi == null)
142      spi = getDefaultProviderInstance(); 
143    return spi.getClassLoader(codebase);
144  }
145 
146  /**
147   * Returns a string representation of the network location where a remote
148   * endpoint can get the class-definition of the given class.
149   *
150   * @param cl
151   *
152   * @return a space seperated list of URLs where the class-definition
153   * of cl may be found
154   */
155  public static String getClassAnnotation(Class<?> cl)
156  {
157    RMIClassLoaderSpi spi = getProviderInstance();
158    if (spi == null)
159      spi = getDefaultProviderInstance(); 
160    return spi.getClassAnnotation(cl);
161  }
162
163  /**
164   * @deprecated
165   */
166  public static Object getSecurityContext (ClassLoader loader)
167  {
168    throw new Error ("Not implemented");
169  }
170
171  /**
172   * Returns the default service provider for <code>RMIClassLoader</code>.
173   *
174   * @return the default provider for <code>RMIClassLoader</code>
175   */
176  public static RMIClassLoaderSpi getDefaultProviderInstance()
177  {
178    return RMIClassLoaderImpl.getInstance();
179  }
180
181  /**
182   * Chooses, instantiates and returns a service provider.
183   *
184   * @return a service provider
185   */
186  private static RMIClassLoaderSpi getProviderInstance()
187  {
188    // If the user asked for the default, return it.  We do a special
189    // check here because our standard service lookup function does not
190    // handle this -- nor should it.
191    String prop = SystemProperties.getProperty("java.rmi.server.RMIClassLoaderSpi");
192    if ("default".equals(prop))
193      return null;
194    Iterator it = ServiceFactory.lookupProviders(RMIClassLoaderSpi.class,
195                                                 null);
196    if (it == null || ! it.hasNext())
197      return null;
198    // FIXME: the spec says we ought to throw an Error of some kind if
199    // the specified provider is not suitable for some reason.  However
200    // our service factory simply logs the problem and moves on to the next
201    // provider in this situation.
202    return (RMIClassLoaderSpi) it.next();
203  }
204}