1. /*
  2. * $Header$
  3. * $Revision$
  4. * $Date$
  5. *
  6. * ====================================================================
  7. *
  8. * The Apache Software License, Version 1.1
  9. *
  10. * Copyright (c) 1999-2002 The Apache Software Foundation. All rights
  11. * reserved.
  12. *
  13. * Redistribution and use in source and binary forms, with or without
  14. * modification, are permitted provided that the following conditions
  15. * are met:
  16. *
  17. * 1. Redistributions of source code must retain the above copyright
  18. * notice, this list of conditions and the following disclaimer.
  19. *
  20. * 2. Redistributions in binary form must reproduce the above copyright
  21. * notice, this list of conditions and the following disclaimer in
  22. * the documentation and/or other materials provided with the
  23. * distribution.
  24. *
  25. * 3. The end-user documentation included with the redistribution, if
  26. * any, must include the following acknowlegement:
  27. * "This product includes software developed by the
  28. * Apache Software Foundation (http://www.apache.org/)."
  29. * Alternately, this acknowlegement may appear in the software itself,
  30. * if and wherever such third-party acknowlegements normally appear.
  31. *
  32. * 4. The names "The Jakarta Project", "Commons", and "Apache Software
  33. * Foundation" must not be used to endorse or promote products derived
  34. * from this software without prior written permission. For written
  35. * permission, please contact apache@apache.org.
  36. *
  37. * 5. Products derived from this software may not be called "Apache"
  38. * nor may "Apache" appear in their names without prior written
  39. * permission of the Apache Group.
  40. *
  41. * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
  42. * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  43. * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  44. * DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
  45. * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  46. * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  47. * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
  48. * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
  49. * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  50. * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
  51. * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  52. * SUCH DAMAGE.
  53. * ====================================================================
  54. *
  55. * This software consists of voluntary contributions made by many
  56. * individuals on behalf of the Apache Software Foundation. For more
  57. * information on the Apache Software Foundation, please see
  58. * <http://www.apache.org/>.
  59. *
  60. */
  61. package org.apache.commons.discovery.jdk;
  62. import java.io.IOException;
  63. import java.net.URL;
  64. import java.util.Enumeration;
  65. /**
  66. * @author Richard A. Sitze
  67. */
  68. class JDK11Hooks extends JDKHooks {
  69. private static final ClassLoader systemClassLoader
  70. = new PsuedoSystemClassLoader();
  71. /**
  72. * The thread context class loader is available for JDK 1.2
  73. * or later, if certain security conditions are met.
  74. *
  75. * @return The thread context class loader, if available.
  76. * Otherwise return null.
  77. */
  78. public ClassLoader getThreadContextClassLoader() {
  79. return null;
  80. }
  81. /**
  82. * The system class loader is available for JDK 1.2
  83. * or later, if certain security conditions are met.
  84. *
  85. * @return The system class loader, if available.
  86. * Otherwise return null.
  87. */
  88. public ClassLoader getSystemClassLoader() {
  89. return systemClassLoader;
  90. }
  91. /**
  92. * Implement ClassLoader.getResources for JDK 1.1
  93. *
  94. * On JDK1.1 there is no getResources() method. We emulate this by
  95. * using introspection and doing the lookup ourself, using the list
  96. * of URLs, via getURLs().
  97. */
  98. public Enumeration getResources(ClassLoader loader,
  99. String resourceName)
  100. throws IOException
  101. {
  102. /**
  103. * The simple answer is/was:
  104. * return loader.getResources(resourceName);
  105. *
  106. * However, some classloaders overload the behavior of getResource
  107. * (loadClass, etc) such that the order of returned results changes
  108. * from normally expected behavior.
  109. *
  110. * Example: locate classes/resources from child ClassLoaders first,
  111. * parents last (in some J2EE environs).
  112. *
  113. * The resource returned by getResource() should be the same as the
  114. * first resource returned by getResources(). Unfortunately, this
  115. * is not, and cannot be: getResources() is 'final' in the current
  116. * JDK's (1.2, 1.3, 1.4).
  117. *
  118. * To address this, the implementation of this method will
  119. * return an Enumeration such that the first element is the
  120. * results of getResource, and all trailing elements are
  121. * from getResources. On each iteration, we check so see
  122. * if the resource (from getResources) matches the first resource,
  123. * and eliminate the redundent element.
  124. */
  125. final URL first = (URL)loader.getResource(resourceName);
  126. final Enumeration rest = loader.getResources(resourceName);
  127. return new Enumeration() {
  128. private boolean firstDone = (first == null);
  129. private URL next = getNext();
  130. public Object nextElement() {
  131. URL o = next;
  132. next = getNext();
  133. return o;
  134. }
  135. public boolean hasMoreElements() {
  136. return next != null;
  137. }
  138. private URL getNext() {
  139. URL n;
  140. if (!firstDone) {
  141. /**
  142. * First time through, use results of getReference()
  143. * if they were non-null.
  144. */
  145. firstDone = true;
  146. n = first;
  147. } else {
  148. /**
  149. * Subsequent times through,
  150. * use results of getReferences()
  151. * but take out anything that matches 'first'.
  152. *
  153. * Iterate through list until we find one that
  154. * doesn't match 'first'.
  155. */
  156. n = null;
  157. while (rest.hasMoreElements() && n == null) {
  158. n = (URL)rest.nextElement();
  159. if (first != null &&
  160. n != null &&
  161. n.equals(first))
  162. {
  163. n = null;
  164. }
  165. }
  166. }
  167. return n;
  168. }
  169. };
  170. }
  171. }