java - 如何使用@OneToOne正确注释JPA实体？

Question

同事们，我有两张 table ，选择获取CHAIN:

选择 OD_CHAINS_REQ.CHAIN 来自 OD_CHAINS_REQ 加入 od_face_accs ON od_face_accs.ID = OD_CHAINS_REQ.ACCOUNT 其中 od_face_accs.ACNT='1608290029' 按 OD_CHAINS_REQ.NUM 排序；

OD_CHAINS_REQ 表中的记录少于 10 条，od_face_accs 表中的记录多于 1000 条。

我正在尝试通过 JPA 执行此选择。但是，据我了解，我需要创建实体 OdChainsReqEntity:

    @Entity
    @Table(name = "OD_CHAINS_REQ", schema = "", catalog = "")
    @IdClass(OdChainsReqEntityPK.class)
    public class OdChainsReqEntity {
        private Integer chain;
        private Integer num;
        private Integer account;

        @Id
        @Column(name = "CHAIN")
        public Integer getChain() {
            return chain;
        }

        public void setChain(Integer chain) {
            this.chain = chain;
        }

        @Basic
        @Column(name = "NUM")
        public Integer getNum() {
            return num;
        }

        public void setNum(Integer num) {
            this.num = num;
        }

        @Id
        @Column(name = "ACCOUNT")
        public Integer getAccount() {
            return account;
        }

        public void setAccount(Integer account) {
            this.account = account;
        }


    @OneToOne
    @JoinColumn(name = "ACCOUNT", referencedColumnName = "ID")
    private OdFaceAccsEntity odFaceAccsEntity;
    public OdFaceAccsEntity getOdFaceAccsEntity() {
        return odFaceAccsEntity;
    }

    public void setOdFaceAccsEntity(OdFaceAccsEntity odFaceAccsEntity) {
        this.odFaceAccsEntity = odFaceAccsEntity;
    }

    /*@Overrides*/*/

}

和OdFaceAccsEntity实体:

@Entity
@Table(name = "OD_FACE_ACCS", schema = "", catalog = "")
public class OdFaceAccsEntity {
    private Integer id;
    private String acnt;



    @Id
    @Column(name = "ID")
    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }



    @Basic
    @Column(name = "ACNT")
    public String getAcnt() {
        return acnt;
    }

    public void setAcnt(String acnt) {
        this.acnt = acnt;
    }

    /*@Overrides*/


    @OneToOne
    @JoinColumn (referencedColumnName = "ACCOUNT")
    private OdChainsReqEntity odChainsReqEntity;

    public OdChainsReqEntity getOdChainsReqEntity() {
        return odChainsReqEntity;
    }

    public void setOdChainsReqEntity(OdChainsReqEntity odChainsReqEntity) {
        this.odChainsReqEntity = odChainsReqEntity;
    }

}

所以我正在尝试使用测试来获取 Chain

 @Test
    public void getChainByDepoAcc() throws Exception {

        OdFaceAccsEntity odFaceAccsEntity = new OdFaceAccsEntity();
        odFaceAccsEntity.setAcnt("1608290029");


        List<OdFaceAccsEntity> odFaceAccsEntities = odFaceAccsDAO.getAcc(odFaceAccsEntity);

        for (int i = 0; i < odFaceAccsEntities.size(); i++) {
            LOG.info(odFaceAccsEntities.get(i).getId());
            LOG.info(odFaceAccsEntities.get(i).getOdChainsReqEntity().getChain());
        }
    }

但它返回异常:

Caused by: org.hibernate.MappingException: Could not determine type for: com.alcap.app.JPA.Entities.OdFaceAccsEntity, at table: OD_CHAINS_REQ, for columns: [org.hibernate.mapping.Column(odFaceAccsEntity)]

如何正确指定实体中的关联以避免异常？

更新 我尝试过的最后一个 DAO 实现:

  @Transactional(value = "txMan", readOnly = true)
    public List <OdChainsReqEntity> getOdChainsReqByDEPOAcc(String in$depoAccnt) {
        Query query = em.createQuery("SELECT cre FROM OdChainsReqEntity cre " +
            "join OdFaceAccsEntity fae on fae.id = cre.account "+
           "where fae.acnt = :depoAcc");
         query.setParameter("depoAcc", in$depoAccnt);
        List<OdChainsReqEntity> result =  query.getResultList();
        return result;
    }

我也尝试了这个(但我不知道它是否适合 join select):

public List<OdChainsReqEntity> getOdChainsReqByAnyParam(OdChainsReqEntity odChainsReqEntity) {

        CriteriaBuilder cb = em.getCriteriaBuilder();
        CriteriaQuery<OdChainsReqEntity> criteriaQuery = cb.createQuery(OdChainsReqEntity.class);
        Root<OdChainsReqEntity> entityRoot = criteriaQuery.from(OdChainsReqEntity.class);

        Predicate criteria = cb.conjunction();

        if (odChainsReqEntity.getChain() != null) {Predicate p = cb.equal(entityRoot.get("chain"), odChainsReqEntity.getChain()); criteria = cb.and(criteria, p);}
        if (odChainsReqEntity.getNum() != null) {Predicate p = cb.equal(entityRoot.get("num"), odChainsReqEntity.getNum()); criteria = cb.and(criteria, p);}
        if (odChainsReqEntity.getAccount() != null) {Predicate p = cb.equal(entityRoot.get("account"), odChainsReqEntity.getAccount()); criteria = cb.and(criteria, p);}


        criteriaQuery.where(criteria);
        List<OdChainsReqEntity> result = em.createQuery(criteriaQuery).getResultList();

        return result;

    }

Answer 1

您尚未发布 DAO 实现。假设它是正确的，则问题可能是以下之一:

1. 您定义的访问类型不一致。您将映射注释(@Column、@OneToOne、...)放置在 getter 方法以及规范未定义的实体字段上。因此，将映射注释移动到字段或 getter 上，但不能同时移动到两者上:

   @Entity
   @Table(name = "OD_FACE_ACCS", schema = "", catalog = "")
   @Access(AccessType.PROPERTY)
   public class OdFaceAccsEntity {
       private Integer id;
       private String acnt;
       private OdChainsReqEntity odChainsReqEntity;
   
       @Id
       public Integer getId() {
           return id;
       }
   
       public void setId(Integer id) {
           this.id = id;
       }
   
       public String getAcnt() {
           return acnt;
       }
   
       public void setAcnt(String acnt) {
          this.acnt = acnt;
       }
   
       /*@Overrides*/
   
       @OneToOne(mappedBy = "odFaceAccsEntity")
       public OdChainsReqEntity getOdChainsReqEntity() {
           return odChainsReqEntity;
       }
   
       public void setOdChainsReqEntity(OdChainsReqEntity odChainsReqEntity) {
           this.odChainsReqEntity = odChainsReqEntity;
        }
   
   }
   
   
   
   @Entity
   @Table(name = "OD_CHAINS_REQ", schema = "", catalog = "")
   @IdClass(OdChainsReqEntityPK.class)
   @Access(AccessType.PROPERTY)
   public class OdChainsReqEntity {
       private Integer chain;
       private Integer num;
       private Integer account;
       private OdFaceAccsEntity odFaceAccsEntity;
   
       // the rest of the code here
   
       @OneToOne
       @JoinColumn(name = "ACCOUNT", referencedColumnName = "ID")
       public OdFaceAccsEntity getOdFaceAccsEntity() {
           return odFaceAccsEntity;
       }
   
       // the rest of the code
   
   }
   

如您所见，我在 getter 方法上移动了所有必要的映射注释(我只是删除了一些注释以节省空间，因为它们默认存在)。

第二个问题是您在两个实体上放置了不正确的 @JoinColumn 注释。您必须仅将此注释放置在关系的一侧，该一侧应该是关系的所有者；在一对一关系中，将注释放置在哪一侧并不重要。关系的另一端需要映射为@OneToOne(mappedBy = "")。我刚刚将 OdFaceAccsEntity 实体设置为关系的反面并进行相应更改(请参阅上面代码中的 @OneToOne)。如果您不希望该实体成为反面，只需反转注释即可

以下是 JPA 2.0 specification 的部分您可以阅读以了解如何正确映射:

• 2.3 访问类型
• 2.10.1 双向一对一关系