javax.persistence.ManyToMany Maven / Gradle / Ivy
package javax.persistence;
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;
import java.lang.annotation.Retention;
import java.lang.annotation.Target;
/**
* 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 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 "";
/**
* (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.
*/
@SuppressWarnings("rawtypes")
Class targetEntity() default void.class;
}