@MappedSuperclass

@MappedSuperclass

 

 

예시

상황가정

이 애플리케이션은 모든 곳에 등록, 수정과 관련된 정보가 항상 있어야 한다.

이 때 Member에

private String createdBy;

private LocalDateTime createdDate;

private String lastModifiedBy;

private LocalDateTime lastModifiedDate;

써 줘도 되지만 번거롭고 중복되므로

BaseEntity로 묶어서 새로 하나 만들고, @MappedSuperClass 넣어주고,

나머지 클래스는 이 클래스를 상속받게 만든다.

 

BaseEntity

@MappedSuperclass // 매핑 정보만 받는 부모클래스
public class BaseEntity {

  private String createdBy;
  private LocalDateTime createdDate;
  private String lastModifiedBy;
  private LocalDateTime lastModifiedDate;

  public String getCreatedBy() {
    return createdBy;
  }

  public void setCreatedBy(String createdBy) {
    this.createdBy = createdBy;
  }

  public LocalDateTime getCreatedDate() {
    return createdDate;
  }

  public void setCreatedDate(LocalDateTime createdDate) {
    this.createdDate = createdDate;
  }

  public String getLastModifiedBy() {
    return lastModifiedBy;
  }

  public void setLastModifiedBy(String lastModifiedBy) {
    this.lastModifiedBy = lastModifiedBy;
  }

  public LocalDateTime getLastModifiedDate() {
    return lastModifiedDate;
  }

  public void setLastModifiedDate(LocalDateTime lastModifiedDate) {
    this.lastModifiedDate = lastModifiedDate;
  }
}

 

Member 변경

@Entity
@NoArgsConstructor
public class Member extends BaseEntity {

  @Id
  @GeneratedValue(strategy = GenerationType.AUTO)
  @Column(name = "MEMBER_ID")
  private Long id;

  //양방향 추가(역방향)
  @ManyToOne
  @JoinColumn(name = "TEAM_ID",insertable = false, updatable = false) // 읽기 전용화 
  private Team team;

  @Column(name = "USERNAME")
  private String username;

  @OneToOne
  @JoinColumn(name = "LOCKER_ID")
  private Locker locker;

  @OneToMany(mappedBy = "member")
  private List<MemberProduct> memberProducts = new ArrayList<>();

//  private String createdBy;
//  private LocalDateTime createdDate;
//  private String lastModifiedBy;
//  private LocalDateTime lastModifiedDate;

  public Long getId() {
    return id;
  }

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

  public String getUsername() {
    return username;
  }

  public void setUsername(String username) {
    this.username = username;
  }

}

Team 변경

@Entity
public class Team extends BaseEntity {

  @Id
  @GeneratedValue
  @Column(name = "TEAM_ID")
  private Long id;

  private String name;

  // 여기가 이제 연관관계를 관맇라기 위해 추가
  @OneToMany
//  @JoinColumn(name = "TEAM_ID")
  private List<Member> members = new ArrayList<>();

//  private String createdBy;
//  private LocalDateTime createdDate;
//  private String lastModifiedBy;
//  private LocalDateTime lastModifiedDate;

  public Long getId() {
    return id;
  }

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

  public String getName() {
    return name;
  }

  public void setName(String name) {
    this.name = name;
  }

  public List<Member> getMembers() {
    return members;
  }

  public void setMembers(List<Member> members) {
    this.members = members;
  }
}

 

 

JpaMain 에도 값 좀 다르게 집어넣으면

public class JpaMain {
  public static void main(String[] args) {
    EntityManagerFactory emf = Persistence.createEntityManagerFactory("hello");
    EntityManager em = emf.createEntityManager();

    EntityTransaction tx = em.getTransaction();
    tx.begin();

    try {
      Member member = new Member();
      member.setUsername("user1");
      member.setCreatedBy("kim");
      member.setCreatedDate(LocalDateTime.now());

      em.persist(member);

      tx.commit();
    } catch (Exception e) {
      tx.rollback();
    } finally {
      em.close();
    }
    emf.close();
  }
}

 

실행해보면

Hibernate: 
    
    create table Member (
       MEMBER_ID bigint not null,
        createdBy varchar(255),
        createdDate timestamp,
        lastModifiedBy varchar(255),
        lastModifiedDate timestamp,
        USERNAME varchar(255),
        LOCKER_ID bigint,
        TEAM_ID bigint,
        primary key (MEMBER_ID)
    )

Hibernate: 
    
    create table Team (
       TEAM_ID bigint not null,
        createdBy varchar(255),
        createdDate timestamp,
        lastModifiedBy varchar(255),
        lastModifiedDate timestamp,
        name varchar(255),
        primary key (TEAM_ID)
    )

 

결국 @MappedSuperclass 속성은

상속관계 매핑 이런 게 아니고

여기 있는 속성을 공통적으로 그냥 가져다 쓰는 것.