src/javax/persistence/ManyToOne.java

/*******************************************************************************
* Copyright (c) 1998, 2009 Oracle. 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.
* 
* The API for this class and its comments are derived from the JPA 2.0 specification 
* which is developed under the Java Community Process (JSR 317) and is copyright 
* Sun Microsystems, Inc. 
*
* Contributors:
*     pkrogh -        Java Persistence API 2.0 Public Draft
*                     Specification and licensing terms available from
*                     http://jcp.org/en/jsr/detail?id=317
*
* EARLY ACCESS - PUBLIC DRAFT
* This is an implementation of an early-draft specification developed under the 
* Java Community Process (JCP) and is made available for testing and evaluation 
* purposes only. The code is not compatible with any specification of the JCP.
******************************************************************************/
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;

/**
 * This annotation defines 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.
 *
 * <pre>
 *
 *     Example:
 *
 *     &#064;ManyToOne(optional=false) 
 *     &#064;JoinColumn(name="CUST_ID", nullable=false, updatable=false)
 *     public Customer getCustomer() { return customer; }
 * </pre>
 *
 * @since Java Persistence API 1.0
 */
@Target({METHOD, FIELD}) 
@Retention(RUNTIME)

public @interface ManyToOne {

    /** 
     * (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.
     *
     * <p> By default no operations are 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 persistence provider runtime that 
     * the associated entity must be eagerly fetched. The {@link FetchType#LAZY 
     * 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.
     */
    boolean optional() default true;
}