Hibernate：为复合PK,FK指定mappedBy属性的正确值

Question

@Embeddable
public class UserID  implements Serializable {

    private static final long serialVersionUID = 1L;
    private int ssnID;
    private int uniqueNum;
    // getters and setters..
}

@Embeddable
public class VehicleID implements Serializable {
    private int vehicleID;
    private int regNum;
    // getters and setters
}

@Entity
public class Vehicle {

    @EmbeddedId
    private VehicleID vehicleID;
    private String description;
    // getters and setters..
}

@Entity
public class UserInfo {
    private String full_name;
    @EmbeddedId
    UserID userID;

    @OneToOne(cascade=CascadeType.ALL)
    @JoinColumns({@JoinColumn(name="vehicle_ID") , @JoinColumn(name="reg_Num")}) // Composite primary key in Vehicle
    Vehicle veh;
    // getters, setters and other code
}

@OneToOne(cascade=CascadeType.ALL)
@JoinColumns({@JoinColumn(name="vehicle_ID") , @JoinColumn(name="reg_Num")})
Vehicle veh;

现在，当我想使它成为双向关系时，我们需要使用mappedby属性，这是我无法理解引用什么属性的地方。

@Ent/ity
public class Vehicle {
    @EmbeddedId
    private VehicleID vehicleID;
    private String description;

    @OneToOne(mappedBy="UserID")
    private UserInfo userInfo;

    // getters and setters..
}

我保留了“userid”作为UserInfo的“复合”主键，但它引发了异常：

线程“main”org.hibernate.annotationexception：在：com.example.entity.vehicle.UserInfo中未知的mappedBy,引用的属性未知：com.example.entity.userinfo.userid

有人能帮我弄明白这一点吗？

Answer 1

应该是这样的：

@OneToOne(mappedBy="veh")
private UserInfo userInfo;

mappedby元素标识关系的反面。这里有Vehicle和UserInfo之间的关系，所以要识别关系的反面，应该使用它的另一面属性。这里veh。

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