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
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7 * published by the Free Software Foundation. Oracle designates this
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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 *
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24 */
25
26 package javax.xml.bind.annotation;
27
28 import java.lang.annotation.Target;
29 import java.lang.annotation.Retention;
30 import static java.lang.annotation.ElementType.*;
31 import static java.lang.annotation.RetentionPolicy.*;
32
33 /**
34 * <p>
35 * Maps a JavaBean property to XML IDREF.
36 *
37 * <p>
38 * To preserve referential integrity of an object graph across XML
39 * serialization followed by a XML deserialization, requires an object
40 * reference to be marshaled by reference or containment
41 * appropriately. Annotations <tt>@XmlID</tt> and <tt>@XmlIDREF</tt>
42 * together allow a customized mapping of a JavaBean property's
43 * type by containment or reference.
44 *
45 * <p><b>Usage</b> </p>
46 * The <tt>@XmlIDREF</tt> annotation can be used with the following
47 * program elements:
48 * <ul>
49 * <li> a JavaBean property </li>
50 * <li> non static, non transient field </li>
51 * </ul>
52 *
53 * <p>See "Package Specification" in javax.xml.bind.package javadoc for
54 * additional common information.</p>
55 *
56 * <p> The usage is subject to the following constraints:
57 * <ul>
58 *
59 * <li> If the type of the field or property is a collection type,
60 * then the collection item type must contain a property or
61 * field annotated with <tt>@XmlID</tt>. </li>
62 * <li> If the field or property is single valued, then the type of
63 * the property or field must contain a property or field
64 * annotated with <tt>@XmlID</tt>.
65 * <p>Note: If the collection item type or the type of the
66 * property (for non collection type) is java.lang.Object, then
67 * the instance must contain a property/field annotated with
68 * <tt>@XmlID</tt> attribute.
69 * </li>
70 * <li> This annotation can be used with the following annotations:
71 * {@link XmlElement}, {@link XmlAttribute}, {@link XmlList},
72 * and {@link XmlElements}.</li>
73 *
74 * </ul>
75 * <p><b>Example:</b> Map a JavaBean property to <tt>xs:IDREF</tt>
76 * (i.e. by reference rather than by containment)</p>
77 * <pre>
78 *
79 * //EXAMPLE: Code fragment
80 * public class Shipping {
81 * @XmlIDREF public Customer getCustomer();
82 * public void setCustomer(Customer customer);
83 * ....
84 * }
85 * {@code
86 *
87 * <!-- Example: XML Schema fragment -->
88 * <xs:complexType name="Shipping">
89 * <xs:complexContent>
90 * <xs:sequence>
91 * <xs:element name="customer" type="xs:IDREF"/>
92 * ....
93 * </xs:sequence>
94 * </xs:complexContent>
95 * </xs:complexType>
96 *
97 * }</pre>
98 *
99 *
100 * <p><b>Example 2: </b> The following is a complete example of
101 * containment versus reference.
102 *
103 * <pre>
104 * // By default, Customer maps to complex type <tt>xs:Customer</tt>
105 * public class Customer {
106 *
107 * // map JavaBean property type to <tt>xs:ID</tt>
108 * @XmlID public String getCustomerID();
109 * public void setCustomerID(String id);
110 *
111 * // .... other properties not shown
112 * }
113 *
114 *
115 * // By default, Invoice maps to a complex type <tt>xs:Invoice</tt>
116 * public class Invoice {
117 *
118 * // map by reference
119 * @XmlIDREF public Customer getCustomer();
120 * public void setCustomer(Customer customer);
121 *
122 * // .... other properties not shown here
123 * }
124 *
125 * // By default, Shipping maps to complex type <tt>xs:Shipping</tt>
126 * public class Shipping {
127 *
128 * // map by reference
129 * @XmlIDREF public Customer getCustomer();
130 * public void setCustomer(Customer customer);
131 * }
132 *
133 * // at least one class must reference Customer by containment;
134 * // Customer instances won't be marshalled.
135 * @XmlElement(name="CustomerData")
136 * public class CustomerData {
137 * // map reference to Customer by containment by default.
138 * public Customer getCustomer();
139 *
140 * // maps reference to Shipping by containment by default.
141 * public Shipping getShipping();
142 *
143 * // maps reference to Invoice by containment by default.
144 * public Invoice getInvoice();
145 * }
146 * {@code
147 *
148 * <!-- XML Schema mapping for above code frament -->
149 *
150 * <xs:complexType name="Invoice">
151 * <xs:complexContent>
152 * <xs:sequence>
153 * <xs:element name="customer" type="xs:IDREF"/>
154 * ....
155 * </xs:sequence>
156 * </xs:complexContent>
157 * </xs:complexType>
158 *
159 * <xs:complexType name="Shipping">
160 * <xs:complexContent>
161 * <xs:sequence>
162 * <xs:element name="customer" type="xs:IDREF"/>
163 * ....
164 * </xs:sequence>
165 * </xs:complexContent>
166 * </xs:complexType>
167 *
168 * <xs:complexType name="Customer">
169 * <xs:complexContent>
170 * <xs:sequence>
171 * ....
172 * </xs:sequence>
173 * <xs:attribute name="CustomerID" type="xs:ID"/>
174 * </xs:complexContent>
175 * </xs:complexType>
176 *
177 * <xs:complexType name="CustomerData">
178 * <xs:complexContent>
179 * <xs:sequence>
180 * <xs:element name="customer" type="xs:Customer"/>
181 * <xs:element name="shipping" type="xs:Shipping"/>
182 * <xs:element name="invoice" type="xs:Invoice"/>
183 * </xs:sequence>
184 * </xs:complexContent>
185 * </xs:complexType>
186 *
187 * <xs:element name"customerData" type="xs:CustomerData"/>
188 *
189 * <!-- Instance document conforming to the above XML Schema -->
190 * <customerData>
191 * <customer customerID="Alice">
192 * ....
193 * </customer>
194 *
195 * <shipping customer="Alice">
196 * ....
197 * </shipping>
198 *
199 * <invoice customer="Alice">
200 * ....
201 * </invoice>
202 * </customerData>
203 *
204 * }</pre>
205 *
206 * <p><b>Example 3: </b> Mapping List to repeating element of type IDREF
207 * <pre>
208 * // Code fragment
209 * public class Shipping {
210 * @XmlIDREF
211 * @XmlElement(name="Alice")
212 * public List customers;
213 * }
214 * {@code
215 *
216 * <!-- XML schema fragment -->
217 * <xs:complexType name="Shipping">
218 * <xs:sequence>
219 * <xs:choice minOccurs="0" maxOccurs="unbounded">
220 * <xs:element name="Alice" type="xs:IDREF"/>
221 * </xs:choice>
222 * </xs:sequence>
223 * </xs:complexType>
224 * }</pre>
225 *
226 * <p><b>Example 4: </b> Mapping a List to a list of elements of type IDREF.
227 * <pre>
228 * //Code fragment
229 * public class Shipping {
230 * @XmlIDREF
231 * @XmlElements(
232 * @XmlElement(name="Alice", type="Customer.class")
233 * @XmlElement(name="John", type="InternationalCustomer.class")
234 * public List customers;
235 * }
236 * {@code
237 *
238 * <!-- XML Schema fragment -->
239 * <xs:complexType name="Shipping">
240 * <xs:sequence>
241 * <xs:choice minOccurs="0" maxOccurs="unbounded">
242 * <xs:element name="Alice" type="xs:IDREF"/>
243 * <xs:element name="John" type="xs:IDREF"/>
244 * </xs:choice>
245 * </xs:sequence>
246 * </xs:complexType>
247 * }</pre>
248 * @author Sekhar Vajjhala, Sun Microsystems, Inc.
249 * @see XmlID
250 * @since 1.6, JAXB 2.0
251 */
252
253 @Retention(RUNTIME) @Target({FIELD, METHOD})
254 public @interface XmlIDREF {}