javax.persistence.ManyToMany Maven / Gradle / Ivy
// $Id: ManyToMany.java 17752 2009-10-15 01:19:21Z [email protected] $
// EJB3 Specification Copyright 2004-2009 Sun Microsystems, Inc.
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.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({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.
*/
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.
*/
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.
*/
FetchType fetch() default LAZY;
/**
* The field that owns the relationship. Required unless
* the relationship is unidirectional.
*/
String mappedBy() default "";
}