Java tutorial
/******************************************************************************* * Copyright (c) 2008 - 2017 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: * Lukas Jungmann - Java Persistence 2.2 * 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.FIELD; import static java.lang.annotation.ElementType.METHOD; import static java.lang.annotation.ElementType.TYPE; import static java.lang.annotation.RetentionPolicy.RUNTIME; import java.lang.annotation.Repeatable; /** * Defines a primary key generator that may be * referenced by name when a generator element is specified for * the {@link GeneratedValue} annotation. A table generator * may be specified on the entity class or on the primary key * field or property. The scope of the generator name is global * to the persistence unit (across all generator types). * * <pre> * Example 1: * * @Entity public class Employee { * ... * @TableGenerator( * name="empGen", * table="ID_GEN", * pkColumnName="GEN_KEY", * valueColumnName="GEN_VALUE", * pkColumnValue="EMP_ID", * allocationSize=1) * @Id * @GeneratedValue(strategy=TABLE, generator="empGen") * int id; * ... * } * * Example 2: * * @Entity public class Address { * ... * @TableGenerator( * name="addressGen", * table="ID_GEN", * pkColumnName="GEN_KEY", * valueColumnName="GEN_VALUE", * pkColumnValue="ADDR_ID") * @Id * @GeneratedValue(strategy=TABLE, generator="addressGen") * int id; * ... * } * </pre> * * @see GeneratedValue * * @since Java Persistence 1.0 */ @Repeatable(TableGenerators.class) @Target({ TYPE, METHOD, FIELD }) @Retention(RUNTIME) public @interface TableGenerator { /** * (Required) A unique generator name that can be referenced * by one or more classes to be the generator for id values. */ String name(); /** * (Optional) Name of table that stores the generated id values. * <p> Defaults to a name chosen by persistence provider. */ String table() default ""; /** (Optional) The catalog of the table. * <p> Defaults to the default catalog. */ String catalog() default ""; /** (Optional) The schema of the table. * <p> Defaults to the default schema for user. */ String schema() default ""; /** * (Optional) Name of the primary key column in the table. * <p> Defaults to a provider-chosen name. */ String pkColumnName() default ""; /** * (Optional) Name of the column that stores the last value generated. * <p> Defaults to a provider-chosen name. */ String valueColumnName() default ""; /** * (Optional) The primary key value in the generator table * that distinguishes this set of generated values from others * that may be stored in the table. * <p> Defaults to a provider-chosen value to store in the * primary key column of the generator table */ String pkColumnValue() default ""; /** * (Optional) The initial value to be used to initialize the column * that stores the last value generated. */ int initialValue() default 0; /** * (Optional) The amount to increment by when allocating id * numbers from the generator. */ int allocationSize() default 50; /** * (Optional) Unique constraints that are to be placed on the * table. These are only used if table generation is in effect. * These constraints apply in addition to primary key constraints. * <p> Defaults to no additional constraints. */ UniqueConstraint[] uniqueConstraints() default {}; /** * (Optional) Indexes for the table. These are only used if * table generation is in effect. Note that it is not necessary * to specify an index for a primary key, as the primary key * index will be created automatically. * * @since Java Persistence 2.1 */ Index[] indexes() default {}; }