Java tutorial
/******************************************************************************* * Copyright (c) 2008 - 2013 Oracle Corporation. All rights reserved. * * This program and the accompanying materials are made available under the * terms of the Eclipse Public License v1.0 and Eclipse Distribution License v. 1.0 * which accompanies this distribution. * The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v10.html * and the Eclipse Distribution License is available at * http://www.eclipse.org/org/documents/edl-v10.php. * * Contributors: * Linda DeMichiel - Java Persistence 2.1 * Linda DeMichiel - Java Persistence 2.0 * ******************************************************************************/ package javax.persistence; import java.lang.annotation.Target; import java.lang.annotation.Retention; import static java.lang.annotation.ElementType.TYPE; import static java.lang.annotation.RetentionPolicy.RUNTIME; /** * Specifies a composite primary key class that is mapped to * multiple fields or properties of the entity. * * <p> The names of the fields or properties in the primary key * class and the primary key fields or properties of the entity * must correspond and their types must be the same. * * <pre> * * Example: * * @IdClass(com.acme.EmployeePK.class) * @Entity * public class Employee { * @Id String empName; * @Id Date birthDay; * ... * } * </pre> * * @since Java Persistence 1.0 */ @Target({ TYPE }) @Retention(RUNTIME) public @interface IdClass { /** Primary key class */ Class value(); }