是否可以执行下列操作...JPA:是否可以将派生类保存在其自己的表中,从而引用的字段是MappedSuperclass?
我有一个名为MappedSuperclass行动:
@MappedSuperclass
public class Action extends EntityBase
{
private static final long serialVersionUID = 2604473746836781718L;
private String event;
public String getEvent()
{
return event;
}
public void setEvent(String event)
{
this.event = event;
}
}
而且我有2类(实体),从这个类派生,例如GenericAction:
@Entity
@Table(name = "GENERIC_ACTION")
@AttributeOverrides({@AttributeOverride(name = "id", column = @Column(name = "GAC_ID")),
@AttributeOverride(name = "version", column = @Column(name = "GAC_VERSION")), @AttributeOverride(name = "event", column = @Column(name = "GAC_EVENT"))})
public class GenericAction extends Action
{
private static final long serialVersionUID = 2694061082912048881L;
@Column(name = "GAC_PAYLOAD")
private String payload;
public String getPayload()
{
return payload;
}
public void setPayload(String payload)
{
this.payload = payload;
}
}
在另一个实体,称为杂志有这样的动作属性设置:
@Entity
@Table(name = "JOURNAL")
@AttributeOverrides({@AttributeOverride(name = "id", column = @Column(name = "JRN_ID")),
@AttributeOverride(name = "version", column = @Column(name = "JRN_VERSION"))})
public class Journal extends EntityBase
{
private static final long serialVersionUID = 2525323851057436815L;
@Column(name = "JRN_ACTION")
private Action action;
}
在我的代码中,我实例GenericAction并将其设置为Journal的setter。当Journal将被保存时,它应该将GenericAction的内容保存在它自己的表中,但这不会发生。它将GenericAction的字节码保存到日志的操作字段中。
这可能吗?
你说得对,它与继承类型.TABLE_PER_CLASS一起工作。我把它放在一个抽象类“ActionBase”和GenericAction(和其他动作)扩展这个类。 – Bevor 2012-04-19 06:51:38