小编jnr*_*jnr的帖子

OneToMany + MapKeyJoinColumn对我不起作用,请说明我做错了什么.

我正在使用JPA 2.0 + Hibernate 3.6.1并希望映射以下表:

到课程:

@Entity
public class Question {
    // id and other fields

    @OneToMany(mappedBy="question", cascade = CascadeType.ALL)
    @MapKeyJoinColumn(name="language_id")
    private Map<Language, Statement> statements =
        new HashMap<Language, Statement>();
}

@Entity
public class Statement {
    @Id
    private Long id;

    @ManyToOne
    @JoinColumn(name = "language_id", nullable = true)
    private Language language;

    @ManyToOne
    @JoinColumn(name = "question_id", nullable = false)
    private Question question;

    @Column(name = "message")
    private String message;
}

@Entity
public class Language {
    @Id
    private Long id;

    @Column(name = …