ManyToOne (Java EE 5 SDK)

javax.persistence Annotation Type ManyToOne

@Target(value={METHOD,FIELD})
@Retention(value=RUNTIME)
public @interface ManyToOne

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.

     Example:

     @ManyToOne(optional=false) 
     @JoinColumn(name="CUST_ID", nullable=false, updatable=false)
     public Customer getCustomer() { return customer; }
 

从以下版本开始:

Java Persistence 1.0

targetEntity

public abstract Class targetEntity

(Optional) The entity class that is the target of the association.

Defaults to the type of the field or property that stores the association.

默认值:

void.class

cascade

public abstract CascadeType[] cascade

(Optional) The operations that must be cascaded to the target of the association.

By default no operations are cascaded.

默认值:

{}

fetch

public abstract FetchType fetch

(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.

默认值:

EAGER

optional

public abstract boolean optional

(Optional) Whether the association is optional. If set to false then a non-null relationship must always exist.

默认值:

true

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