001: /*
002: * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
003: *
004: * Copyright 1997-2007 Sun Microsystems, Inc. All rights reserved.
005: *
006: * The contents of this file are subject to the terms of either the GNU
007: * General Public License Version 2 only ("GPL") or the Common Development
008: * and Distribution License("CDDL") (collectively, the "License"). You
009: * may not use this file except in compliance with the License. You can obtain
010: * a copy of the License at https://glassfish.dev.java.net/public/CDDL+GPL.html
011: * or glassfish/bootstrap/legal/LICENSE.txt. See the License for the specific
012: * language governing permissions and limitations under the License.
013: *
014: * When distributing the software, include this License Header Notice in each
015: * file and include the License file at glassfish/bootstrap/legal/LICENSE.txt.
016: * Sun designates this particular file as subject to the "Classpath" exception
017: * as provided by Sun in the GPL Version 2 section of the License file that
018: * accompanied this code. If applicable, add the following below the License
019: * Header, with the fields enclosed by brackets [] replaced by your own
020: * identifying information: "Portions Copyrighted [year]
021: * [name of copyright owner]"
022: *
023: * Contributor(s):
024: *
025: * If you wish your version of this file to be governed by only the CDDL or
026: * only the GPL Version 2, indicate your decision by adding "[Contributor]
027: * elects to include this software in this distribution under the [CDDL or GPL
028: * Version 2] license." If you don't indicate a single choice of license, a
029: * recipient has the option to distribute your version of this file under
030: * either the CDDL, the GPL Version 2 or to extend the choice of license to
031: * its licensees as provided above. However, if you add GPL Version 2 code
032: * and therefore, elected the GPL Version 2 license, then the option applies
033: * only if the new code is made subject to such option by the copyright
034: * holder.
035: */
036: package javax.persistence;
037:
038: import java.lang.annotation.Target;
039: import java.lang.annotation.Retention;
040: import static java.lang.annotation.ElementType.FIELD;
041: import static java.lang.annotation.ElementType.METHOD;
042: import static java.lang.annotation.RetentionPolicy.RUNTIME;
043:
044: /**
045: * Is used to specify the map key for associations of type
046: * {@link java.util.Map}.
047: *
048: * <p> If a persistent field or property other than the primary
049: * key is used as a map key then it is expected to have a
050: * uniqueness constraint associated with it.
051: *
052: * <pre>
053: *
054: * Example 1:
055: *
056: * @Entity
057: * public class Department {
058: * ...
059: * @OneToMany(mappedBy="department")
060: * @MapKey(name="empId")
061: * public Map<Integer, Employee> getEmployees() {... }
062: * ...
063: * }
064: *
065: * @Entity
066: * public class Employee {
067: * ...
068: * @Id Integer getEmpid() { ... }
069: * @ManyToOne
070: * @JoinColumn(name="dept_id")
071: * public Department getDepartment() { ... }
072: * ...
073: * }
074: *
075: * Example 2:
076: *
077: * @Entity
078: * public class Department {
079: * ...
080: * @OneToMany(mappedBy="department")
081: * @MapKey(name="empPK")
082: * public Map<EmployeePK, Employee> getEmployees() {... }
083: * ...
084: * }
085: *
086: * @Entity
087: * public class Employee {
088: * @EmbeddedId public EmployeePK getEmpPK() { ... }
089: * ...
090: * @ManyToOne
091: * @JoinColumn(name="dept_id")
092: * public Department getDepartment() { ... }
093: * ...
094: * }
095: *
096: * @Embeddable
097: * public class EmployeePK {
098: * String name;
099: * Date bday;
100: * }
101: * </pre>
102: *
103: * @since Java Persistence 1.0
104: */
105: @Target({METHOD,FIELD})
106: @Retention(RUNTIME)
107: public @interface MapKey {
108:
109: /**
110: * The name of the persistent field or property of the
111: * associated entity that is used as the map key. If the
112: * name element is not specified, the primary key of the
113: * associated entity is used as the map key. If the
114: * primary key is a composite primary key and is mapped
115: * as {@link IdClass}, an instance of the primary key
116: * class is used as the key.
117: */
118: String name() default "";
119: }
|