OneToOne


1   /*
2    * The contents of this file are subject to the terms 
3    * of the Common Development and Distribution License 
4    * (the License).  You may not use this file except in
5    * compliance with the License.
6    * 
7    * You can obtain a copy of the license at 
8    * https://glassfish.dev.java.net/public/CDDLv1.0.html or
9    * glassfish/bootstrap/legal/CDDLv1.0.txt.
10   * See the License for the specific language governing 
11   * permissions and limitations under the License.
12   * 
13   * When distributing Covered Code, include this CDDL 
14   * Header Notice in each file and include the License file 
15   * at glassfish/bootstrap/legal/CDDLv1.0.txt.  
16   * If applicable, add the following below the CDDL Header, 
17   * with the fields enclosed by brackets [] replaced by
18   * you own identifying information: 
19   * "Portions Copyrighted [year] [name of copyright owner]"
20   * 
21   * Copyright 2006 Sun Microsystems, Inc. All rights reserved.
22   */
23  package javax.persistence;
24  
25  import java.lang.annotation.Target  ;
26  import java.lang.annotation.Retention  ;
27  import javax.persistence.CascadeType;
28  import static java.lang.annotation.ElementType.METHOD  ;
29  import static java.lang.annotation.ElementType.FIELD  ;
30  import static java.lang.annotation.RetentionPolicy.RUNTIME  ;
31  import static javax.persistence.FetchType.EAGER;
32  
33  /**
34   * This annotation defines a single-valued association to 
35   * another entity that has one-to-one multiplicity. It is not 
36   * normally necessary to specify the associated target entity 
37   * explicitly since it can usually be inferred from the type 
38   * of the object being referenced.
39   *
40   * <pre>
41   *    Example 1: One-to-one association that maps a foreign key column
42   *
43   *    On Customer class:
44   *
45   *    &#064;OneToOne(optional=false)
46   *    &#064;JoinColumn(
47   *      name="CUSTREC_ID", unique=true, nullable=false, updatable=false)
48   *    public CustomerRecord getCustomerRecord() { return customerRecord; }
49   *
50   *    On CustomerRecord class:
51   *
52   *    &#064;OneToOne(optional=false, mappedBy="customerRecord")
53   *    public Customer getCustomer() { return customer; }
54   *
55   *    Example 2: One-to-one association that assumes both the source and target share the same primary key values. 
56   *
57   *    On Employee class:
58   *
59   *    &#064;Entity
60   *    public class Employee {
61   *      &#064;Id Integer id;
62   *    
63   *      &#064;OneToOne &#064;PrimaryKeyJoinColumn
64   *      EmployeeInfo info;
65   *      ...
66   *    }
67   *
68   *    On EmployeeInfo class:
69   *
70   *    &#064;Entity
71   *    public class EmployeeInfo {
72   *      &#064;Id Integer id;
73   *      ...
74   *    }
75   * </pre>
76   *
77   * @since Java Persistence 1.0
78   */
79  @Target  ({METHOD, FIELD}) 
80  @Retention  (RUNTIME)
81  
82  public @interface OneToOne {
83  
84      /** 
85       * (Optional) The entity class that is the target of 
86       * the association. 
87       *
88       * <p> Defaults to the type of the field or property 
89       * that stores the association. 
90       */
91      Class   targetEntity() default void.class;
92  
93      /**
94       * (Optional) The operations that must be cascaded to 
95       * the target of the association.
96       *
97       * <p> By default no operations are cascaded.
98       */
99      CascadeType[] cascade() default {};
100 
101     /** 
102      * (Optional) Whether the association should be lazily 
103      * loaded or must be eagerly fetched. The {@link FetchType#EAGER EAGER} 
104      * strategy is a requirement on the persistence provider runtime that 
105      * the associated entity must be eagerly fetched. The {@link FetchType#LAZY 
106      * LAZY} strategy is a hint to the persistence provider runtime.
107      */
108     FetchType fetch() default EAGER;
109 
110     /** 
111      * (Optional) Whether the association is optional. If set 
112      * to false then a non-null relationship must always exist.
113      */
114     boolean optional() default true;
115 
116     /** (Optional) The field that owns the relationship. This 
117       * element is only specified on the inverse (non-owning) 
118       * side of the association.
119      */
120     String   mappedBy() default "";
121 }
122
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