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.tools;
  62. import org.apache.commons.discovery.ResourceClass;
  63. import org.apache.commons.discovery.ResourceClassIterator;
  64. import org.apache.commons.discovery.resource.classes.DiscoverClasses;
  65. import org.apache.commons.discovery.resource.ClassLoaders;
  66. /**
  67. * Holder for a default class.
  68. *
  69. * Class may be specified by name (String) or class (Class).
  70. * Using the holder complicates the users job, but minimized # of API's.
  71. *
  72. * @author Richard A. Sitze
  73. */
  74. public class DefaultClassHolder {
  75. private Class defaultClass;
  76. private final String defaultName;
  77. public DefaultClassHolder(Class defaultClass) {
  78. this.defaultClass = defaultClass;
  79. this.defaultName = defaultClass.getName();
  80. }
  81. public DefaultClassHolder(String defaultName) {
  82. this.defaultClass = null;
  83. this.defaultName = defaultName;
  84. }
  85. /**
  86. * @param spi non-null SPI
  87. * @param loaders Used only if class needs to be loaded.
  88. *
  89. * @return Default Class. Load the class if necessary,
  90. * and verify that it implements the SPI.
  91. * (this forces the check, no way out..).
  92. */
  93. public Class getDefaultClass(SPInterface spi, ClassLoaders loaders) {
  94. if (defaultClass == null) {
  95. DiscoverClasses classDiscovery = new DiscoverClasses(loaders);
  96. ResourceClassIterator classes = classDiscovery.findResourceClasses(getDefaultName());
  97. if (classes.hasNext()) {
  98. ResourceClass info = classes.nextResourceClass();
  99. try {
  100. defaultClass = info.loadClass();
  101. } catch (Exception e) {
  102. // ignore
  103. }
  104. }
  105. }
  106. if (defaultClass != null) {
  107. spi.verifyAncestory(defaultClass);
  108. }
  109. return defaultClass;
  110. }
  111. public String getDefaultName() {
  112. return defaultName;
  113. }
  114. }