Question

我有两个实体之间的一对一关联，但其中一个必须有两个@Id。一个是PRI，另一个是MUL。我如何声明复合ID，以及如何映射类？

@Entity
@Table(name = "PERSONS")
public class Person implements Serializable{
    private static final long serialVersionUID = -3451407520028311143L;
    @Id
    @Column(name = "ID")
    private Integer id;

    @Column(name = "ADDRESS_ID")
    private Integer addressId;

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

    @OneToOne(mappedBy= "person", cascade= CascadeType.ALL)
    private Address address;
     ...
}

第二个类通过@IdClass注释

进行映射

@Entity
@Table ( name = "ADDRESS" )
@IdClass(AddressKeys.class)
public class Address implements Serializable {


    @Id
    @Column ( name = "ID")
    private Integer id;

    @Id
    @Column ( name = "PERSON_ID")
    private Integer idPerson;

    @Column ( name = "CITY" )
    private String city;

    @OneToOne(cascade= CascadeType.ALL)
    @JoinColumn(name="PERSON_ID")
    private Person person;
...
}

和id类

class AddressKeys implements Serializable{
    private Integer id;
    private Integer idPerson;

    //getters and setters

    @Override
    public int hashCode() {
        ...
        return result;
    }

    @Override
    public boolean equals(Object obj) {
        ...
    }

}

因此，当我尝试创建并保存记录时，我有下一个错误

无法在实体的映射中打开sessionRepeated列： hibernateMappedModels.base1.mappedClasses.oneToOne.Address列： PERSON_ID（应使用insert =＆＃34; false＆＃34; update =＆＃34; false＆＃34;）映射 java.lang.NullPointerException at hibernateMappedModels.base1.Main.run（Main.java:45）at hibernateMappedModels.base1.Main.main（Main.java:24

我尝试将Id字段设置为unInsertable和unUpdatable，并且它正在工作，但我需要它们是可插入和可更新的;有没有可能做到这一点？

Answer 1

我对你的映射感到困惑，并且不确定除了下面的简单映射之外还需要什么：如果我遗漏了某些内容，那么你需要扩展你的问题。在将列映射两次时会出现错误 - 一次是通过一对一，一次是作为简单属性。另外，我不确定为什么在地址上需要复合键。

@Entity
@Table(name = "PERSONS")
public class Person implements Serializable{
    private static final long serialVersionUID = -3451407520028311143L;

    @Id
    @Column(name = "ID")
    private Integer id;

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

    @OneToOne(mappedBy= "person", cascade= CascadeType.ALL)
    private Address address;

}

@Entity
@Table ( name = "ADDRESS" )
public class Address implements Serializable {


    @Id
    @Column ( name = "ID")
    private Integer id;

    @Column ( name = "CITY" )
    private String city;

    @OneToOne(cascade= CascadeType.ALL)
    @JoinColumn(name="PERSON_ID")
    private Person person;
}

与所有者实体的复合ID的一对一关联

1 个答案: