javax.persistence.ManyToMany Maven / Gradle / Ivy
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/*
* Copyright (c) 2008, 2009, 2011 Oracle, Inc. 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.
*/
package javax.persistence;
import java.lang.annotation.Retention;
import java.lang.annotation.Target;
import static java.lang.annotation.ElementType.ANNOTATION_TYPE;
import static java.lang.annotation.ElementType.FIELD;
import static java.lang.annotation.ElementType.METHOD;
import static java.lang.annotation.RetentionPolicy.RUNTIME;
import static javax.persistence.FetchType.LAZY;
/**
* Defines a many-valued association with many-to-many multiplicity.
*
* Every many-to-many association has two sides, the owning side and the non-owning, or inverse, side. The
* join table is specified on the owning side. If the association is bidirectional, either side may be
* designated as the owning side. If the relationship is bidirectional, the non-owning side must use the
* mappedBy element of the ManyToMany annotation to specify the relationship field
* or property of the owning side.
*
* The join table for the relationship, if not defaulted, is specified on the owning side.
*
* The ManyToMany annotation may be used within an embeddable class contained within an entity
* class to specify a relationship to a collection of entities. If the relationship is bidirectional and the
* entity containing the embeddable class is the owner of the relationship, the non-owning side must use the
* mappedBy element of the ManyToMany annotation to specify the relationship field
* or property of the embeddable class. The dot (".") notation syntax must be used in the
* mappedBy element to indicate the relationship attribute within the embedded attribute. The
* value of each identifier used with the dot notation is the name of the respective embedded field or
* property.
*
*
*
* Example 1:
*
* // In Customer class:
*
* @ManyToMany
* @JoinTable(name="CUST_PHONES")
* public Set<PhoneNumber> getPhones() { return phones; }
*
* // In PhoneNumber class:
*
* @ManyToMany(mappedBy="phones")
* public Set<Customer> getCustomers() { return customers; }
*
* Example 2:
*
* // In Customer class:
*
* @ManyToMany(targetEntity=com.acme.PhoneNumber.class)
* public Set getPhones() { return phones; }
*
* // In PhoneNumber class:
*
* @ManyToMany(targetEntity=com.acme.Customer.class, mappedBy="phones")
* public Set getCustomers() { return customers; }
*
* Example 3:
*
* // In Customer class:
*
* @ManyToMany
* @JoinTable(name="CUST_PHONE",
* joinColumns=
* @JoinColumn(name="CUST_ID", referencedColumnName="ID"),
* inverseJoinColumns=
* @JoinColumn(name="PHONE_ID", referencedColumnName="ID")
* )
* public Set<PhoneNumber> getPhones() { return phones; }
*
* // In PhoneNumberClass:
*
* @ManyToMany(mappedBy="phones")
* public Set<Customer> getCustomers() { return customers; }
*
* @see JoinTable
* @since Java Persistence 1.0
*/
@Target({ANNOTATION_TYPE, METHOD, FIELD})
@Retention(RUNTIME)
public @interface ManyToMany
{
/**
* (Optional) The entity class that is the target of the association. Optional only if the
* collection-valued relationship property is defined using Java generics. Must be specified otherwise.
*
* Defaults to the parameterized type of the collection when defined using generics.
* @return The target entity
*/
Class targetEntity() default void.class;
/**
* (Optional) The operations that must be cascaded to the target of the association.
*
* When the target collection is a {@link java.util.Map java.util.Map}, the cascade element
* applies to the map value.
*
* Defaults to no operations being cascaded.
* @return The cascade type
*/
CascadeType[] cascade() default {};
/**
* (Optional) Whether the association should be lazily loaded or must be eagerly fetched. The EAGER
* strategy is a requirement on the persistence provider runtime that the associated entities must be
* eagerly fetched. The LAZY strategy is a hint to the persistence provider runtime.
* @return The fetch type
*/
FetchType fetch() default LAZY;
/**
* The field that owns the relationship. Required unless the relationship is unidirectional.
* @return The mappedby
*/
String mappedBy() default "";
}