1 /*
2 * Copyright (c) 2004, 2011, 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
6 * under the terms of the GNU General Public License version 2 only, as
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
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 package javax.xml.bind.annotation;
27
28 import java.lang.annotation.Retention;
29 import java.lang.annotation.Target;
30
31 import static java.lang.annotation.RetentionPolicy.RUNTIME;
32 import static java.lang.annotation.ElementType.TYPE;
33
34 /**
35 * Maps a class or an enum type to an XML element.
36 *
37 * <p> <b>Usage</b> </p>
38 * <p>
39 * The @XmlRootElement annotation can be used with the following program
40 * elements:
41 * <ul>
42 * <li> a top level class </li>
43 * <li> an enum type </li>
44 * </ul>
45 *
46 * <p>See "Package Specification" in javax.xml.bind.package javadoc for
47 * additional common information.</p>
48 *
49 * <p>
50 * When a top level class or an enum type is annotated with the
51 * @XmlRootElement annotation, then its value is represented
52 * as XML element in an XML document.
53 *
54 * <p> This annotation can be used with the following annotations:
55 * {@link XmlType}, {@link XmlEnum}, {@link XmlAccessorType},
56 * {@link XmlAccessorOrder}.
57 * <p>
58
59 * <p>
60 * <b>Example 1: </b> Associate an element with XML Schema type
61 * <pre>
62 * // Example: Code fragment
63 * @XmlRootElement
64 * class Point {
65 * int x;
66 * int y;
67 * Point(int _x,int _y) {x=_x;y=_y;}
68 * }
69 * </pre>
70 *
71 * <pre>
72 * //Example: Code fragment corresponding to XML output
73 * marshal( new Point(3,5), System.out);
74 * </pre>
75 *
76 * <pre>
77 * <!-- Example: XML output -->
78 * <point>
79 * <x> 3 </x>
80 * <y> 5 </y>
81 * </point>
82 * </pre>
83 *
84 * The annotation causes an global element declaration to be produced
85 * in the schema. The global element declaration is associated with
86 * the XML schema type to which the class is mapped.
87 *
88 * <pre>
89 * <!-- Example: XML schema definition -->
90 * <xs:element name="point" type="point"/>
91 * <xs:complexType name="point">
92 * <xs:sequence>
93 * <xs:element name="x" type="xs:int"/>
94 * <xs:element name="y" type="xs:int"/>
95 * </xs:sequence>
96 * </xs:complexType>
97 * </pre>
98 *
99 * <p>
100 *
101 * <b>Example 2: Orthogonality to type inheritance </b>
102 *
103 * <p>
104 * An element declaration annotated on a type is not inherited by its
105 * derived types. The following example shows this.
106 * <pre>
107 * // Example: Code fragment
108 * @XmlRootElement
109 * class Point3D extends Point {
110 * int z;
111 * Point3D(int _x,int _y,int _z) {super(_x,_y);z=_z;}
112 * }
113 *
114 * //Example: Code fragment corresponding to XML output *
115 * marshal( new Point3D(3,5,0), System.out );
116 *
117 * <!-- Example: XML output -->
118 * <!-- The element name is point3D not point -->
119 * <point3D>
120 * <x>3</x>
121 * <y>5</y>
122 * <z>0</z>
123 * </point3D>
124 *
125 * <!-- Example: XML schema definition -->
126 * <xs:element name="point3D" type="point3D"/>
127 * <xs:complexType name="point3D">
128 * <xs:complexContent>
129 * <xs:extension base="point">
130 * <xs:sequence>
131 * <xs:element name="z" type="xs:int"/>
132 * </xs:sequence>
133 * </xs:extension>
134 * </xs:complexContent>
135 * </xs:complexType>
136 * </pre>
137 *
138 * <b>Example 3: </b> Associate a global element with XML Schema type
139 * to which the class is mapped.
140 * <pre>
141 * //Example: Code fragment
142 * @XmlRootElement(name="PriceElement")
143 * public class USPrice {
144 * @XmlElement
145 * public java.math.BigDecimal price;
146 * }
147 *
148 * <!-- Example: XML schema definition -->
149 * <xs:element name="PriceElement" type="USPrice"/>
150 * <xs:complexType name="USPrice">
151 * <xs:sequence>
152 * <xs:element name="price" type="xs:decimal"/>
153 * </sequence>
154 * </xs:complexType>
155 * </pre>
156 *
157 * @author Sekhar Vajjhala, Sun Microsystems, Inc.
158 * @since JAXB2.0
159 */
160 @Retention(RUNTIME)
161 @Target({TYPE})
162 public @interface XmlRootElement {
163 /**
164 * namespace name of the XML element.
165 * <p>
166 * If the value is "##default", then the XML namespace name is derived
167 * from the package of the class ( {@link XmlSchema} ). If the
168 * package is unnamed, then the XML namespace is the default empty
169 * namespace.
170 */
171 String namespace() default "##default";
172
173 /**
174 * local name of the XML element.
175 * <p>
176 * If the value is "##default", then the name is derived from the
177 * class name.
178 *
179 */
180 String name() default "##default";
181
182 }