GeneratedValue (Java EE 5 SDK)

Java

Java EE 5 SDK

深圳电信培训中心.徐海蛟老师.


javax.persistence Annotation Type GeneratedValue


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

Provides for the specification of generation strategies for the values of primary keys. The GeneratedValue annotation may be applied to a primary key property or field of an entity or mapped superclass in conjunction with the Id annotation.


 Example 1:

     @Id
     @GeneratedValue(strategy=SEQUENCE, generator="CUST_SEQ")
     @Column(name="CUST_ID")
     public Long getId() { return id; }

     Example 2:

     @Id
     @GeneratedValue(strategy=TABLE, generator="CUST_GEN")
     @Column(name="CUST_ID")
     Long id;
 

从以下版本开始:
Java Persistence 1.0

Optional Element Summary
 String generator
          (Optional) The name of the primary key generator to use as specified in the SequenceGenerator or TableGenerator annotation.
 GenerationType strategy
          (Optional) The primary key generation strategy that the persistence provider must use to generate the annotated entity primary key.
 

strategy

public abstract GenerationType strategy
(Optional) The primary key generation strategy that the persistence provider must use to generate the annotated entity primary key.

默认值:
AUTO

generator

public abstract String generator
(Optional) The name of the primary key generator to use as specified in the SequenceGenerator or TableGenerator annotation.

Defaults to the id generator supplied by persistence provider.

默认值:
""

Java EE 5 SDK

深圳电信培训中心.徐海蛟老师.


提交错误或意见

版权所有 2007 Sun Microsystems, Inc. 保留所有权利。 请遵守许可证条款。深圳电信培训中心.徐海蛟老师教学参考.