JPA - 不能訪問非實體@MappedSuperclass在多對一關係

Question

不知道如何訪問多對一關係船mappedsuper類JPA。這是我的代碼片段。

消息在非實體映射超（用於消息沒有表） SystemMessage是一個實體類表名是SYSTEM_MESSAGE //工會子類 OrganizationMessage是一個實體類表名是ORGANIZATION_MESSAGE //工會子類

當我嘗試從ORGANIZATION_NOTIFICATION 訪問組織通知域對象，組織通知表具有message_id列（Message）多對多關係。

它沒有加載，它拋出的消息不是實體。即使我嘗試了@entity而不是@mappedsuperclass，但它沒有加載消息。我應該通過組織通知

@MappedSuperClass 
@Inheritance(strategy = InheritanceType.TABLE_PER_CLASS) 
public class Message extends BaseDomain implements Comparable<Message> 
{ 
    private final static Logger log = Logger.getLogger(Message.class); 

    @Id 
    @Column(name = "MESSAGE_ID") 
    @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "MESSAGE_PK_SQ") 
    @SequenceGenerator(name = "MESSAGE_PK_SQ", sequenceName = "MESSAGE_PK_SQ",  allocationSize = 1) 

    private Long id; 
    @Column(name="MESSAGE_NAME") 
    private String name; 
} 

@Entity 
@Table(name = "SYSTEM_MESSAGE") 
@Inheritance(strategy = InheritanceType.SINGLE_TABLE) 
public class SystemMessage extends Message 
{ 
//some persitant variables 
} 


@Entity 
@Table(name = "ORGANIZATION_MESSAGE") 
@Inheritance(strategy = InheritanceType.SINGLE_TABLE) 
public class OrganizationMessage extends Message 
{ 
//some persitant variables 
} 


@SuppressWarnings("serial") 
@Entity 
@Table(name = "ORGANIZATION_NOTIFICATION") 
public class OrganizationNotification extends BaseDomain implements Comparable<OrganizationNotification> 
{ 
@Id 
    @Column(name = "ORGANIZATION_NOTIFICATION_ID") 
    @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "org_notification_pk_sq") 
    @SequenceGenerator(name = "org_notification_pk_sq", sequenceName = "org_notification_pk_sq", allocationSize = 1) 
    private Long id; 


//Here is the issue. when i try to access message it says it is not entity otherwise it is not loading if i use entity in message and not saving. 
@ManyToOne(targetEntity = Message.class) 
    @JoinColumn(name = "MESSAGE_ID", insertable = true, updatable = true, nullable = false,referencedColumnName="MESSAGE_ID") 
    private Message message; 

} 

同時訪問系統信息與組織的消息，你能告訴我任何關於此問題的建議。

Answer 1

另一個實體有消息實例關聯的事實證明，信息不能是MappedSuperclass，而是一個實體。與@Entity而非@MappedSuperclass

註釋消息。

MappedSuperclass用於繼承實體沒有任何共同之處其他領域和/或關聯。