| /******************************************************************************* |
| * 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; |
| import static javax.persistence.DiscriminatorType.STRING; |
| |
| /** |
| * Specifies the discriminator column for the |
| * <code>SINGLE_TABLE</code> and |
| * <code>JOINED</code> {@link Inheritance} mapping strategies. |
| * |
| * <p> The strategy and the discriminator column are only |
| * specified in the root of an entity class hierarchy or |
| * subhierarchy in which a different inheritance strategy is applied |
| * |
| * <p> If the <code>DiscriminatorColumn</code> annotation is missing, |
| * and a discriminator column is required, the name of the |
| * discriminator column defaults to <code>"DTYPE"</code> and the discriminator |
| * type to {@link DiscriminatorType#STRING DiscriminatorType.STRING}. |
| * |
| * <pre> |
| * Example: |
| * |
| * @Entity |
| * @Table(name="CUST") |
| * @Inheritance(strategy=SINGLE_TABLE) |
| * @DiscriminatorColumn(name="DISC", discriminatorType=STRING, length=20) |
| * public class Customer { ... } |
| * |
| * @Entity |
| * public class ValuedCustomer extends Customer { ... } |
| * </pre> |
| * |
| * @see DiscriminatorValue |
| * |
| * @since Java Persistence 1.0 |
| */ |
| @Target({TYPE}) |
| @Retention(RUNTIME) |
| |
| public @interface DiscriminatorColumn { |
| |
| /** |
| * (Optional) The name of column to be used for the discriminator. |
| */ |
| String name() default "DTYPE"; |
| |
| /** |
| * (Optional) The type of object/column to use as a class discriminator. |
| * Defaults to {@link DiscriminatorType#STRING DiscriminatorType.STRING}. |
| */ |
| DiscriminatorType discriminatorType() default STRING; |
| |
| /** |
| * (Optional) The SQL fragment that is used when generating the DDL |
| * for the discriminator column. |
| * <p> Defaults to the provider-generated SQL to create a column |
| * of the specified discriminator type. |
| */ |
| String columnDefinition() default ""; |
| |
| /** |
| * (Optional) The column length for String-based discriminator types. |
| * Ignored for other discriminator types. |
| */ |
| int length() default 31; |
| } |