java – Hibernate @OneToOne与多个对象的关系？

如果我有这样的桌子……

+------------------------------------------------------+
|                         Code                         |
+------------------------------------------------------+
| id |               target_uuid              |  code  |
+----+----------------------------------------+--------+
|  1 | "01BE898A-C5A9-4F86-B0AA-4ACCDCE81B8F" |    0   |
+----+----------------------------------------+--------+
|  2 | "E139F21E-8C93-492B-9E0F-CC773FAE832D" |    2   |
+----+----------------------------------------+--------+

…而target_uuid可以引用Post或User uuid字段,我如何在Hibernate中映射它？

假设uuid不是Post或User的主键.我知道我知道.糟糕的数据模型,但我坚持下去.

我试过这个：

@Entity
@Table(name = "User")
public class User {
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(name = "id")
    private Integer id;

    @Column(name = "uuid")
    private String uuid;

    @OneToOne(mappedBy = "user")
    @JoinColumn(name = "uuid")
    private Code code;

    // getters and setters
}

@Entity
@Table(name = "Post")
public class Post {
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(name = "id")
    private Integer id;

    @Column(name = "uuid")
    private String uuid;

    @OneToOne(mappedBy = "post")
    @JoinColumn(name = "uuid")
    private Code code;

    // getters and setters
}

@Entity
@Table(name = "Code")
public class Code {
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(name = "id")
    private Integer id;

    @Column(name = "code")
    private Integer code;

    @Column(name = "target_uuid")
    private String targetUuid;

    @OneToOne
    @JoinColumn(name = "target_uuid", insertable = false, updatable = false)
    private User user;

    @OneToOne
    @JoinColumn(name = "target_uuid", insertable = false, updatable = false)
    private Post post;

    // getters and setters
}

这不会抛出异常并且似乎有效,但我的User和Post对象不断为其代码属性获取NULL值.

任何人都可以对此有所了解吗？

解决方法:

正如评论中所解释的那样,这种关联是AFAIK,不可能映射为双向关联.您可以将其映射为从Post到Code(以及从User到Code)的OneToOne单向关联,只需将JoinColumn批注的referencedColumnName设置为“target_uuid”即可.

标签：java,hibernate,one-to-one,hibernate-annotations
来源： https://codeday.me/bug/20190703/1365877.html