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1   /*
2    * Copyright (c) 2004, 2013, 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
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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
18   * 2 along with this work; if not, write to the Free Software Foundation,
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  
26  package javax.xml.bind;
27  import  javax.xml.namespace.QName;
28  
29  /**
30   * Provide access to JAXB xml binding data for a JAXB object.
31   *
32   * <p>
33   * Intially, the intent of this class is to just conceptualize how
34   * a JAXB application developer can access xml binding information,
35   * independent if binding model is java to schema or schema to java.
36   * Since accessing the XML element name related to a JAXB element is
37   * a highly requested feature, demonstrate access to this
38   * binding information.
39   *
40   * The factory method to get a <code>JAXBIntrospector</code> instance is
41   * {@link JAXBContext#createJAXBIntrospector()}.
42   *
43   * @see JAXBContext#createJAXBIntrospector()
44   * @since JAXB2.0
45   */
46  public abstract class JAXBIntrospector {
47  
48      /**
49       * <p>Return true if <code>object</code> represents a JAXB element.</p>
50       * <p>Parameter <code>object</code> is a JAXB element for following cases:
51       * <ol>
52       *   <li>It is an instance of <code>javax.xml.bind.JAXBElement</code>.</li>
53       *   <li>The class of <code>object</code> is annotated with
54       *       <code>&#64XmlRootElement</code>.
55       *   </li>
56       * </ol>
57       *
58       * @see #getElementName(Object)
59       */
60      public abstract boolean isElement(Object object);
61  
62      /**
63       * <p>Get xml element qname for <code>jaxbElement</code>.</p>
64       *
65       * @param jaxbElement is an object that {@link #isElement(Object)} returned true.
66       *
67       * @return xml element qname associated with jaxbElement;
68       *         null if <code>jaxbElement</code> is not a JAXB Element.
69       */
70      public abstract QName getElementName(Object jaxbElement);
71  
72      /**
73       * <p>Get the element value of a JAXB element.</p>
74       *
75       * <p>Convenience method to abstract whether working with either
76       *    a javax.xml.bind.JAXBElement instance or an instance of
77       *    <tt>&#64XmlRootElement</tt> annotated Java class.</p>
78       *
79       * @param jaxbElement  object that #isElement(Object) returns true.
80       *
81       * @return The element value of the <code>jaxbElement</code>.
82       */
83      public static Object getValue(Object jaxbElement) {
84          if (jaxbElement instanceof JAXBElement) {
85              return ((JAXBElement)jaxbElement).getValue();
86          } else {
87              // assume that class of this instance is
88              // annotated with @XmlRootElement.
89              return jaxbElement;
90          }
91      }
92  }