1 /*
2 * Copyright (c) 2004, 2015, 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.METHOD;
33
34 /**
35 * Maps a factory method to a XML element.
36 *
37 * <p> <b>Usage</b> </p>
38 *
39 * The annotation creates a mapping between an XML schema element
40 * declaration and a <i> element factory method </i> that returns a
41 * JAXBElement instance representing the element
42 * declaration. Typically, the element factory method is generated
43 * (and annotated) from a schema into the ObjectFactory class in a
44 * Java package that represents the binding of the element
45 * declaration's target namespace. Thus, while the annotation syntax
46 * allows @XmlElementDecl to be used on any method, semantically
47 * its use is restricted to annotation of element factory method.
48 *
49 * The usage is subject to the following constraints:
50 *
51 * <ul>
52 * <li> The class containing the element factory method annotated
53 * with @XmlElementDecl must be marked with {@link
54 * XmlRegistry}. </li>
55 * <li> The element factory method must take one parameter
56 * assignable to {@link Object}.</li>
57 * </ul>
58 *
59 * <p><b>Example 1: </b>Annotation on a factory method
60 * <pre>
61 * // Example: code fragment
62 * @XmlRegistry
63 * class ObjectFactory {
64 * @XmlElementDecl(name="foo")
65 * JAXBElement<String> createFoo(String s) { ... }
66 * }
67 * </pre>
68 * <pre> {@code
69 *
70 * <!-- XML input -->
71 * <foo>string</foo>
72 *
73 * // Example: code fragment corresponding to XML input
74 * JAXBElement<String> o =
75 * (JAXBElement<String>)unmarshaller.unmarshal(aboveDocument);
76 * // print JAXBElement instance to show values
77 * System.out.println(o.getName()); // prints "{}foo"
78 * System.out.println(o.getValue()); // prints "string"
79 * System.out.println(o.getValue().getClass()); // prints "java.lang.String"
80 *
81 * <!-- Example: XML schema definition -->
82 * <xs:element name="foo" type="xs:string"/>
83 * }</pre>
84 *
85 * <p><b>Example 2: </b> Element declaration with non local scope
86 * <p>
87 * The following example illustrates the use of scope annotation
88 * parameter in binding of element declaration in schema derived
89 * code.
90 * <p>
91 * The following example may be replaced in a future revision of
92 * this javadoc.
93 *
94 * <pre>{@code
95 * <!-- Example: XML schema definition -->
96 * <xs:schema>
97 * <xs:complexType name="pea">
98 * <xs:choice maxOccurs="unbounded">
99 * <xs:element name="foo" type="xs:string"/>
100 * <xs:element name="bar" type="xs:string"/>
101 * </xs:choice>
102 * </xs:complexType>
103 * <xs:element name="foo" type="xs:int"/>
104 * </xs:schema>
105 * }</pre>
106 * <pre>
107 * // Example: expected default binding
108 * class Pea {
109 * @XmlElementRefs({
110 * @XmlElementRef(name="foo",type=JAXBElement.class)
111 * @XmlElementRef(name="bar",type=JAXBElement.class)
112 * })
113 * List<JAXBElement<String>> fooOrBar;
114 * }
115 *
116 * @XmlRegistry
117 * class ObjectFactory {
118 * @XmlElementDecl(scope=Pea.class,name="foo")
119 * JAXBElement<String> createPeaFoo(String s);
120 *
121 * @XmlElementDecl(scope=Pea.class,name="bar")
122 * JAXBElement<String> createPeaBar(String s);
123 *
124 * @XmlElementDecl(name="foo")
125 * JAXBElement<Integer> createFoo(Integer i);
126 * }
127 *
128 * </pre>
129 * Without scope createFoo and createPeaFoo would become ambiguous
130 * since both of them map to a XML schema element with the same local
131 * name "foo".
132 *
133 * @see XmlRegistry
134 * @since 1.6, JAXB 2.0
135 */
136 @Retention(RUNTIME)
137 @Target({METHOD})
138 public @interface XmlElementDecl {
139 /**
140 * scope of the mapping.
141 *
142 * <p>
143 * If this is not {@link XmlElementDecl.GLOBAL}, then this element
144 * declaration mapping is only active within the specified class.
145 */
146 Class scope() default GLOBAL.class;
147
148 /**
149 * namespace name of the XML element.
150 * <p>
151 * If the value is "##default", then the value is the namespace
152 * name for the package of the class containing this factory method.
153 *
154 * @see #name()
155 */
156 String namespace() default "##default";
157
158 /**
159 * local name of the XML element.
160 *
161 * <p>
162 * <b> Note to reviewers: </b> There is no default name; since
163 * the annotation is on a factory method, it is not clear that the
164 * method name can be derived from the factory method name.
165 * @see #namespace()
166 */
167 String name();
168
169 /**
170 * namespace name of a substitution group's head XML element.
171 * <p>
172 * This specifies the namespace name of the XML element whose local
173 * name is specified by <tt>substitutionHeadName()</tt>.
174 * <p>
175 * If <tt>susbtitutionHeadName()</tt> is "", then this
176 * value can only be "##default". But the value is ignored since
177 * since this element is not part of susbtitution group when the
178 * value of <tt>susbstitutionHeadName()</tt> is "".
179 * <p>
180 * If <tt>susbtitutionHeadName()</tt> is not "" and the value is
181 * "##default", then the namespace name is the namespace name to
182 * which the package of the containing class, marked with {@link
183 * XmlRegistry }, is mapped.
184 * <p>
185 * If <tt>susbtitutionHeadName()</tt> is not "" and the value is
186 * not "##default", then the value is the namespace name.
187 *
188 * @see #substitutionHeadName()
189 */
190 String substitutionHeadNamespace() default "##default";
191
192 /**
193 * XML local name of a substitution group's head element.
194 * <p>
195 * If the value is "", then this element is not part of any
196 * substitution group.
197 *
198 * @see #substitutionHeadNamespace()
199 */
200 String substitutionHeadName() default "";
201
202 /**
203 * Default value of this element.
204 *
205 * <p>
206 * The <pre>'\u0000'</pre> value specified as a default of this annotation element
207 * is used as a poor-man's substitute for null to allow implementations
208 * to recognize the 'no default value' state.
209 */
210 String defaultValue() default "\u0000";
211
212 /**
213 * Used in {@link XmlElementDecl#scope()} to
214 * signal that the declaration is in the global scope.
215 */
216 public final class GLOBAL {}
217 }