Composite ID and its generation in JPA

Question

I want use custom class like ID

@javax.persistence.Embeddable  
class ObjectID impements Serializable{  
private Long value;    
  //setters, getters and other  
 }  

Here is mapped class

@Entity  
@IdClass(ObjectID.class)  
public class Country implements Serializable   
{  
   @Id  
   @AttributeOverride(name = "value", column = @Column(name = "id"))  
   @SequenceGenerator(name = "CountrySequenceGenerator",  
                       sequenceName = "lab_country_seq")  
   @GeneratedValue(strategy = GenerationType.SEQUENCE,  
                    generator = "CountryCountryGenerator")  
   private ObjectID value;
  // setters, getters, fields  
}  

Doesn't work. Value wasn't generated. Any ideas, how can I generate ID for composite-id?

Answer 1

ID类必须是可序列化的，并实现hashCode和equals