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
/*******************************************************************************
* 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 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.EAGER;
Specifies a single-valued association to another entity class that
has many-to-one multiplicity. It is not normally necessary to
specify the target entity explicitly since it can usually be
inferred from the type of the object being referenced. If the
relationship is bidirectional, the non-owning
OneToMany entity side must used the
mappedBy element to specify the relationship field or
property of the entity that is the owner of the relationship.
The ManyToOne annotation may be used within an
embeddable class to specify a relationship from the embeddable
class to an entity class. If the relationship is bidirectional, the
non-owning OneToMany entity side must use the mappedBy
element of the OneToMany annotation to specify the
relationship field or property of the embeddable field or property
on the owning side of the relationship. 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:
@ManyToOne(optional=false)
@JoinColumn(name="CUST_ID", nullable=false, updatable=false)
public Customer getCustomer() { return customer; }
Example 2:
@Entity
public class Employee {
@Id int id;
@Embedded JobInfo jobInfo;
...
}
@Embeddable
public class JobInfo {
String jobDescription;
@ManyToOne ProgramManager pm; // Bidirectional
}
@Entity
public class ProgramManager {
@Id int id;
@OneToMany(mappedBy="jobInfo.pm")
Collection<Employee> manages;
}
Since: Java Persistence 1.0
/**
* Specifies a single-valued association to another entity class that
* has many-to-one multiplicity. It is not normally necessary to
* specify the target entity explicitly since it can usually be
* inferred from the type of the object being referenced. If the
* relationship is bidirectional, the non-owning
* <code>OneToMany</code> entity side must used the
* <code>mappedBy</code> element to specify the relationship field or
* property of the entity that is the owner of the relationship.
*
* <p> The <code>ManyToOne</code> annotation may be used within an
* embeddable class to specify a relationship from the embeddable
* class to an entity class. If the relationship is bidirectional, the
* non-owning <code>OneToMany</code> entity side must use the <code>mappedBy</code>
* element of the <code>OneToMany</code> annotation to specify the
* relationship field or property of the embeddable field or property
* on the owning side of the relationship. The dot (".") notation
* syntax must be used in the <code>mappedBy</code> 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.
* <pre>
*
* Example 1:
*
* @ManyToOne(optional=false)
* @JoinColumn(name="CUST_ID", nullable=false, updatable=false)
* public Customer getCustomer() { return customer; }
*
*
* Example 2:
*
* @Entity
* public class Employee {
* @Id int id;
* @Embedded JobInfo jobInfo;
* ...
* }
*
* @Embeddable
* public class JobInfo {
* String jobDescription;
* @ManyToOne ProgramManager pm; // Bidirectional
* }
*
* @Entity
* public class ProgramManager {
* @Id int id;
* @OneToMany(mappedBy="jobInfo.pm")
* Collection<Employee> manages;
* }
*
* </pre>
*
* @since Java Persistence 1.0
*/
@Target({METHOD, FIELD})
@Retention(RUNTIME)
public @interface ManyToOne {
(Optional) The entity class that is the target of
the association.
Defaults to the type of the field or property
that stores the association.
/**
* (Optional) The entity class that is the target of
* the association.
*
* <p> Defaults to the type of the field or property
* that stores the association.
*/
Class targetEntity() default void.class;
(Optional) The operations that must be cascaded to
the target of the association.
By default no operations are cascaded.
/**
* (Optional) The operations that must be cascaded to
* the target of the association.
*
* <p> By default no operations are 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 entity must be eagerly fetched. The LAZY
strategy is a hint to the persistence provider runtime.
/**
* (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 entity must be eagerly fetched. The LAZY
* strategy is a hint to the persistence provider runtime.
*/
FetchType fetch() default EAGER;
(Optional) Whether the association is optional. If set
to false then a non-null relationship must always exist.
/**
* (Optional) Whether the association is optional. If set
* to false then a non-null relationship must always exist.
*/
boolean optional() default true;
}