Question

我的数据库中有两个表：

      CREATE TABLE "D"."EMPDIR_DISPLAY" 
   (    "PST_ENTITY_ID" NUMBER NOT NULL ENABLE, 
    "PST_GRP_ID" NUMBER NOT NULL ENABLE, 
    "FIRST_CHAR" CHAR(1 BYTE), 
    "DISPLAY_URL" VARCHAR2(250 BYTE) NOT NULL ENABLE, 
    "DISPLAY_TEXT" VARCHAR2(250 BYTE) NOT NULL ENABLE, 
    "ACTIVE_JOBS" NUMBER DEFAULT 0, 
     CONSTRAINT "PK_EMPDIR_DISPLAY_ID" PRIMARY KEY ("PST_ENTITY_ID")
  USING INDEX PCTFREE 10 INITRANS 2 MAXTRANS 255 COMPUTE STATISTICS 
  STORAGE(INITIAL 65536 NEXT 1048576 MINEXTENTS 1 MAXEXTENTS 2147483645
  PCTINCREASE 0 FREELISTS 1 FREELIST GROUPS 1 BUFFER_POOL DEFAULT)
  TABLESPACE "PROVIDER"  ENABLE
   ) PCTFREE 10 PCTUSED 40 INITRANS 1 MAXTRANS 255 NOCOMPRESS LOGGING
  STORAGE(INITIAL 65536 NEXT 1048576 MINEXTENTS 1 MAXEXTENTS 2147483645
  PCTINCREASE 0 FREELISTS 1 FREELIST GROUPS 1 BUFFER_POOL DEFAULT)
  TABLESPACE "PROVIDER" ;

和

 CREATE TABLE "D"."PST_ENTITY" 
   (    "PST_ENTITY_ID" NUMBER(*,0) NOT NULL ENABLE, 
    "PST_ENTITY_GRP_NAME" VARCHAR2(50 BYTE) NOT NULL ENABLE, 
    "PST_ENTITY_REGION" NUMBER(*,0) NOT NULL ENABLE, 
    "PST_ENTITY_NAME" VARCHAR2(50 BYTE), 
    "PST_ENTITY_CITY" VARCHAR2(30 BYTE), 
    "PST_ENTITY_STATE" CHAR(2 BYTE), 
    "PST_ENTITY_SMALL_LOGO" VARCHAR2(100 BYTE), 
    "PST_ENTITY_LARGE_LOGO" VARCHAR2(100 BYTE), 
    "PST_ENTITY_HOME_URL" VARCHAR2(500 BYTE), 
    "PST_ENTITY_CAREER_URL" VARCHAR2(100 BYTE), 
    "PST_ENTITY_LOGO_PLACEMENT" VARCHAR2(50 BYTE), 
    "PST_ENTITY_TEXT_COLOR" VARCHAR2(50 BYTE), 
    "PST_ENTITY_BG_COLOR" VARCHAR2(50 BYTE), 
    "PST_ENTITY_PROFILE" VARCHAR2(2048 BYTE), 
    "FIRST_CHAR" CHAR(1 BYTE), 
    "PST_ENTITY_STYLESHEET" VARCHAR2(512 BYTE), 
    "PST_ENTITY_CUSTOM_JSP" VARCHAR2(512 BYTE), 
    "PST_ENTITY_LOCATION_OPTION" NUMBER(*,0), 
    "PST_ENTITY_ECP_IMAGE" VARCHAR2(512 BYTE), 
     CONSTRAINT "PK_PST_ENTITY" PRIMARY KEY ("PST_ENTITY_ID")
  USING INDEX PCTFREE 10 INITRANS 2 MAXTRANS 255 COMPUTE STATISTICS 
  STORAGE(INITIAL 196608 NEXT 1048576 MINEXTENTS 1 MAXEXTENTS 2147483645
  PCTINCREASE 0 FREELISTS 1 FREELIST GROUPS 1 BUFFER_POOL DEFAULT)
  TABLESPACE "PROVIDER"  ENABLE, 
     CONSTRAINT "FK_PST_REGION_ID" FOREIGN KEY ("PST_ENTITY_REGION")
      REFERENCES "D"."PST_REGION" ("PST_REGION_ID") ENABLE
   ) PCTFREE 10 PCTUSED 40 INITRANS 1 MAXTRANS 255 NOCOMPRESS LOGGING
  STORAGE(INITIAL 4194304 NEXT 1048576 MINEXTENTS 1 MAXEXTENTS 2147483645
  PCTINCREASE 0 FREELISTS 1 FREELIST GROUPS 1 BUFFER_POOL DEFAULT)
  TABLESPACE "PROVIDER" ;

我已经创建了具有序列的模型，其中ENTITY_ID是从DB SEQ获得的：

@Entity
@Table(name="PST_ENTITY")
@Cache(region = "com.daoservice.service.model.EntityModel", usage = CacheConcurrencyStrategy.READ_WRITE)

public class EntityModel {

@Id
@SequenceGenerator(name="entityIdGen" , sequenceName = "PST_ENTITY_ID_SEQ", allocationSize = 1)
@GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "entityIdGen")
@Column(name="PST_ENTITY_ID", unique = true,  nullable = false  )
private Integer pstEntityId;

@Column(name="PST_ENTITY_GRP_NAME",  nullable = false  )
private String pstEntityGrpName;


@Column(name="PST_ENTITY_REGION",  nullable = false  )
private Integer pstEntityRegion;
...

和

@Entity
@Table(name="EMPDIR_DISPLAY")
@Cache(region = "com.companies.daoservice.service.model.EmployerDirModel", usage = CacheConcurrencyStrategy.READ_WRITE)

public class EmployerDirModel {

@Id
@GenericGenerator(name = "entityIdGen", strategy = "foreign", parameters = @Parameter(name = "property", value = "entityModel"))
@GeneratedValue(generator = "entityIdGen")
@Column(name="PST_ENTITY_ID", unique = true,  nullable = false  )
private Integer pstEntityId;

@Column(name="PST_GRP_ID",  nullable = false  )
private Integer pstGrpId;
...

现在，当我坚持这些模型时，EntityModel会被持久化甚至获取生成的seq。然而，由于EntityId存在一些问题，EmployerDirModel无疑会抛出一个NPE。

Answer 1

如果要在两个类之间共享ID，请使用连接列。

@Entity
class MedicalHistory implements Serializable {
  @Id @OneToOne
  @JoinColumn(name = "person_id")
  Person patient;
}

@Entity
public class Person implements Serializable {
  @Id @GeneratedValue Integer id;
}

可选地，

@Entity
class MedicalHistory implements Serializable {
  @Id Integer id;

  @MapsId @OneToOne
  @JoinColumn(name = "patient_id")
  Person patient;
}

@Entity
class Person {
  @Id @GeneratedValue Integer id;
}

来源：Hibernate Doc

在两个表上持久保存db生成的值

1 个答案: