javax.persistence.ManyToMany Maven / Gradle / Ivy
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package javax.persistence;
import java.lang.annotation.Target;
import java.lang.annotation.Retention;
import javax.persistence.CascadeType;
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.
* If the Collection is defined using generics to specify the element
* type, the associated target entity class does not need to be
* specified; otherwise it must be specified.
*
* 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.
*
*
The same annotation elements for the {@link OneToMany}
* annotation apply to the ManyToMany annotation.
*
*
*
* Example 1:
*
* In Customer class:
*
* @ManyToMany
* @JoinTable(name="CUST_PHONES")
* public Set getPhones() { return phones; }
*
* In PhoneNumber class:
*
* @ManyToMany(mappedBy="phones")
* public Set 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 getPhones() { return phones; }
*
* In PhoneNumberClass:
*
* @ManyToMany(mappedBy="phones")
* public Set getCustomers() { return customers; }
*
*
* @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
* 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.
*
Defaults to no operations being cascaded.
*/
CascadeType[] cascade() default {};
/** (Optional) Whether the association should be
* lazily loaded or must be eagerly fetched. The
* {@link FetchType#EAGER EAGER} strategy is a
* requirement on the persistenceprovider runtime
* that the associatedentities must be eagerly fetched.
* The {@link FetchType#LAZY 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 "";
}