인프런 커뮤니티 질문&답변

// JpaMain.java

package hellojpa;

import jakarta.persistence.*;

import java.util.List;

public class JpaMain {

    public static void main(String[] args) {

        EntityManagerFactory emf = Persistence.createEntityManagerFactory("hello");
        EntityManager em = emf.createEntityManager();

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

        //code

        try {
            Movie movie = new Movie();
            movie.setDirector("aaaa");
            movie.setActor("bbbb");
            movie.setName("바람과함께사라지다");
            movie.setPrice(10000);

            System.out.println("=== BEFORE ===");
            em.persist(movie);
            System.out.println("=== AFTER ===");

            System.out.println("movie.getId() = " + movie.getId());
            em.flush();
            em.clear();
            System.out.println("movie.getId() = " + movie.getId());

            Movie findMovie = em.find(Movie.class, movie.getId());


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

        }


        emf.close();
    }
}

// Item.java

package hellojpa;

import jakarta.persistence.*;

@Entity
@Inheritance(strategy = InheritanceType.TABLE_PER_CLASS)
public abstract class Item {

    @Id
    @GeneratedValue
    private Long id;

    private String name;

    private int price;

    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 int getPrice() {
        return price;
    }

    public void setPrice(int price) {
        this.price = price;
    }
}

// Book.java

package hellojpa;

import jakarta.persistence.DiscriminatorValue;
import jakarta.persistence.Entity;

@Entity
public class Book extends Item {
    private String author;
    private String isbn;

}

// Movie.java

package hellojpa;

import jakarta.persistence.DiscriminatorValue;
import jakarta.persistence.Entity;

@Entity
public class Movie extends Item {

    private String director;
    private String actor;

    public String getDirector() {
        return director;
    }

    public void setDirector(String director) {
        this.director = director;
    }

    public String getActor() {
        return actor;
    }

    public void setActor(String actor) {
        this.actor = actor;
    }
}

// Album.java

package hellojpa;

import jakarta.persistence.DiscriminatorValue;
import jakarta.persistence.Entity;

@Entity
public class Album extends Item {

    private String artist;
}

TABLE_PER_CLASS 전략을 사용했는데도 ITEM 테이블이 생기고 ITEM 테이블에 값이 들어갔는데 왜 이러는 건가요?