Spring Data JPA @OneToOne注释无限递归错误

Question

丈夫.java

package com.example.demo.com.example.domain;

import lombok.Data;
import lombok.EqualsAndHashCode;
import lombok.NoArgsConstructor;
import lombok.ToString;

import javax.persistence.*;


//@Data
//@NoArgsConstructor
//@EqualsAndHashCode
//@ToString
@Entity
@Table(name = "t_husban")
public class Husband {
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long id;

    private String name;
    private String job;

    @OneToOne
    @JoinColumn(name = "wife_fk",referencedColumnName = "id")
    private Wife wife;

    //omitted getter/setter
}

妻子.java

package com.example.demo.com.example.domain;

import lombok.Data;
import lombok.EqualsAndHashCode;
import lombok.NoArgsConstructor;
import lombok.ToString;

import javax.persistence.*;

//@Data
//@NoArgsConstructor
@EqualsAndHashCode(exclude = "husband",callSuper = false)
@Entity
@Table(name = "t_wife")
public class Wife {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long id;

    private String name;

    @OneToOne(mappedBy = "wife",cascade = {CascadeType.ALL})
    private Husband husband;

    //omitted getter/setter
}

Service.java

@Service

    public class TestOneToOneEitherSide {

        @Autowired
        private WifeRepository wifeDao;

        @Autowired
        private HusbandRepository husbandDao;
        public Husband testCreate() {

            Husband husband = husbandDao.findByName("Wang");
            return husband;
        }
    }

当我使用spring数据jpa从数据库中查询丈夫时，结果发生无限递归，参见下图。使用@OneToOne注释时出了什么问题？有人可以给我一些建议吗？或者我以错误的方式使用了注释。

图片

Answer 1

这是一个已知问题，当您具有双向关系时，杰克逊将尝试从另一侧序列化一侧的每个引用，以便逻辑上具有无限递归。

解决方案：有很多解决方案，可以在一侧使用@JsonIgnore以避免序列化带注释的引用，从而破坏了无限递归

 @EqualsAndHashCode(exclude = "husband",callSuper = false)
 @Entity
@Table(name = "t_wife")
public class Wife {

@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private Long id;

private String name;

@OneToOne(mappedBy = "wife",cascade = {CascadeType.ALL})
@JsonIgnore
private Husband husband;

//omitted getter/setter
}

您也可以使用@ JsonManagedReference / @
JsonBackReference，请查看此链接以获取更多有关如何使用它们的信息

这个答案有一个问题，如果您尝试序列化妻子的方向，您将没有丈夫对象，因为解决方案是避免序列化它。

有一个很好的解决方案，它在此链接中提到，其思想是生成对父实体的引用，因此，如果您要序列化丈夫，您将拥有丈夫->妻子-> [引用丈夫而不是丈夫]
，您所需要做的就是使用@JsonIdentityInfo注释您的实体

@EqualsAndHashCode(exclude = "husband",callSuper = false)
@Entity
@Table(name = "t_wife")
@JsonIdentityInfo(generator=ObjectIdGenerators.UUIDGenerator.class, property="@id")
public class Wife {

@JsonIdentityInfo(generator=ObjectIdGenerators.UUIDGenerator.class, property="@id")
@Entity
@Table(name = "t_husban")
public class Husband {
@Id