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.METHOD; import static java.lang.annotation.ElementType.FIELD; import static java.lang.annotation.RetentionPolicy.RUNTIME; import static javax.persistence.ConstraintMode.PROVIDER_DEFAULT; /** * Specifies the table that is used for the mapping of * collections of basic or embeddable types. Applied * to the collection-valued field or property. * * <p>By default, the columns of the collection table that correspond * to the embeddable class or basic type are derived from the * attributes of the embeddable class or from the basic type according * to the default values of the <code>Column</code> annotation. In the case * of a basic type, the column name is derived from the name of the * collection-valued field or property. In the case of an embeddable * class, the column names are derived from the field or property * names of the embeddable class. * <ul> * <li> To override the default properties of the column used for a * basic type, the <code>Column</code> annotation is used on the * collection-valued attribute in addition to the * <code>ElementCollection</code> annotation. * * <li> To override these defaults for an embeddable class, the * <code>AttributeOverride</code> and/or * <code>AttributeOverrides</code> annotations can be used in * addition to the <code>ElementCollection</code> annotation. If the * embeddable class contains references to other entities, the default * values for the columns corresponding to those references may be * overridden by means of the <code>AssociationOverride</code> and/or * <code>AssociationOverrides</code> annotations. * </ul> * * <p> If the <code>CollectionTable</code> annotation is missing, the * default values of the <code>CollectionTable</code> annotation * elements apply. * * <pre> * Example: * * @Embeddable public class Address { * protected String street; * protected String city; * protected String state; * ... * } * * @Entity public class Person { * @Id protected String ssn; * protected String name; * protected Address home; * ... * @ElementCollection // use default table (PERSON_NICKNAMES) * @Column(name="name", length=50) * protected Set<String> nickNames = new HashSet(); * ... * } * * @Entity public class WealthyPerson extends Person { * @ElementCollection * @CollectionTable(name="HOMES") // use default join column name * @AttributeOverrides({ * @AttributeOverride(name="street", * column=@Column(name="HOME_STREET")), * @AttributeOverride(name="city", * column=@Column(name="HOME_CITY")), * @AttributeOverride(name="state", * column=@Column(name="HOME_STATE")) * }) * protected Set<Address> vacationHomes = new HashSet(); * ... * } * </pre> * * @see ElementCollection * @see AttributeOverride * @see AssociationOverride * @see Column * * @since Java Persistence 2.0 */ @Target({ METHOD, FIELD }) @Retention(RUNTIME) public @interface CollectionTable { /** * (Optional) The name of the collection table. If not specified, * it defaults to the concatenation of the name of the containing * entity and the name of the collection attribute, separated by * an underscore. */ String name() default ""; /** * (Optional) The catalog of the table. If not specified, the * default catalog is used. */ String catalog() default ""; /** * (Optional) The schema of the table. If not specified, the * default schema for the user is used. */ String schema() default ""; /** * (Optional) The foreign key columns of the collection table * which reference the primary table of the entity. The default * only applies if a single join column is used. The default is * the same as for <code>JoinColumn</code> (i.e., the * concatenation of the following: the name of the entity; "_"; * the name of the referenced primary key column.) However, if * there is more than one join column, a <code>JoinColumn</code> * annotation must be specified for each join column using the * <code>JoinColumns</code> annotation. In this case, both the * <code>name</code> and the <code>referencedColumnName</code> * elements must be specified in each such * <code>JoinColumn</code> annotation. */ JoinColumn[] joinColumns() default {}; /** * (Optional) Used to specify or control the generation of a * foreign key constraint for the columns corresponding to the * <code>joinColumns</code> element when table generation is in * effect. If both this element and the <code>foreignKey</code> * element of any of the <code>joinColumns</code> elements are * specified, the behavior is undefined. If no foreign key * annotation element is specified in either location, the * persistence provider's default foreign key strategy will * apply. * * @since Java Persistence 2.1 */ ForeignKey foreignKey() default @ForeignKey(PROVIDER_DEFAULT); /** * (Optional) Unique constraints that are to be placed on the * table. These are only used if table generation is in effect. */ UniqueConstraint[] uniqueConstraints() default {}; /** * (Optional) Indexes for the table. These are only used if * table generation is in effect. * * @since Java Persistence 2.1 */ Index[] indexes() default {}; }