扩展非抽象的JPA实体类

Question

I've been searching the web for some answers but no luck so far.

I need to extend an existing entity to add some fields.

Say we have a class which is already being used in the project

@Entity
public class SampleEntity {
    @Id 
    private Long id;
    // some fields
}

And I want to create another one, that adds some additional fields. Something like

@Entity
public class SampleExtendedEntity extends SampleEntity {
    // some more fields
}

I am looking for a solution that would create a new db table with just those additional fields and a foreign key for SampleEntity . Ideally this foreign key would also be a primary key of SampleExtendedEntity

A very simple way to do that would be to use composition and @OneToOne , but due to semantics I really want to use inheritance. Unfortunatelly @MappedSuperclass and @Inheritance don't work for me, because the entity I'm extending is a class that can be (and is) used as standalone. Any suggestions would be appreciated

Answer 1

@Entity
public class SampleExtendedEntity extends SampleEntity {
    // some more fields
int foreignKey=-1;

public SampleExtendedEntity(int key){
this.foreignKey=key;
}

public int getforeignKey(){
return foreignKey();
}
public static void main(String[] args){
SampleExtendedEntity myEntity= new SampleExtendedEntity(2);
//SampleEntity  needs a getter method for ID
System.out.println(myEntity.getForeignKey()+" "+myEntity.getId());

}

}