H2 表没有变化(未创建对象)由 JPA 智能

Question

我想用jpa系统创建对象，

但是在我创建对象之后，

h2控制台没有变化

我希望物体是这样制作的，在这里输入图像描述

(想创建ITEM和MOVIE对象)

但是我得到的是这个。输入图片描述

这些是我写的代码。

package hellojpa;
import javax.persistence.Entity;
@Entity
public class Album extends Item{
private String artist;
}

package hellojpa;
import javax.persistence.Entity;
@Entity
public class Book extends Item{
private String author;
private String isbn;
}

package hellojpa;
import org.hibernate.engine.internal.JoinSequence;
import org.hibernate.mapping.Join;
import javax.persistence.*;
@Entity
@Inheritance(strategy = InheritanceType.JOINED)
public 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;
}
}

package hellojpa;
import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.EntityTransaction;
import javax.persistence.Persistence;
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{
Movie movie = new Movie();
movie.setDirector("aaaa");
movie.setActor("bbbb");
movie.setName("바람과 함께 사라지다");
movie.setPrice(10000);
tx.commit();
}catch(Exception e){
tx.rollback();
} finally{
em.close();
}
emf.close();
}
}

package hellojpa;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.OneToOne;
@Entity
public class Locker {
@Id
@GeneratedValue
private  Long id;
private String name;
@OneToOne(mappedBy = "locker")
private Member member;
}

package hellojpa;
import net.bytebuddy.dynamic.TypeResolutionStrategy;
import org.hibernate.annotations.Fetch;
import javax.persistence.*;
import java.util.ArrayList;
import java.util.List;
@Entity
public class Member {
@Id @GeneratedValue
@Column(name = "MEMBER_ID")
private Long id;
@Column(name = "USERNAME")
private String username;
@ManyToOne
@JoinColumn(name = "Team_ID",insertable = false, updatable = false)
private Team team;
@OneToOne
@JoinColumn(name ="LOCKER_ID")
private Locker locker;
@OneToMany(mappedBy = "member")
private List<MemberProduct> memberProducts = new ArrayList<>();
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;}

}

package hellojpa;
import javax.persistence.*;
import java.time.LocalDateTime;
@Entity
public class MemberProduct {
@Id
@GeneratedValue
private Long id;
@ManyToOne
@JoinColumn(name="MEMBER_ID")
private Member member;
@ManyToOne
@JoinColumn(name = "PRODUCT_ID")
private Product product;
private int count;
private int price;
private LocalDateTime orderDateTime;
}

package hellojpa;
import javax.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;
}

}

package hellojpa;
import javax.persistence.*;
import java.util.ArrayList;
import java.util.List;
@Entity
public class Product {
@Id
@GeneratedValue
private Long id;
private String name;
@OneToMany (mappedBy = "product")
private List<MemberProduct> memberProducts = new ArrayList<>();
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;
}
}

package hellojpa;
public enum RoleType {
GUEST, USER, ADMIN
}

package hellojpa;
import javax.persistence.*;
import java.util.ArrayList;
import java.util.List;
@Entity
public class Team {
@Id @GeneratedValue
@Column(name = "TEAM_ID")
private Long id;
private String name;
@OneToMany
@JoinColumn(name = "TEAM_ID")
private List<Member> members = new ArrayList<>();
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;
}
}

<?xml version="1.0" encoding="UTF-8"?>
<persistence version="2.2"
xmlns="http://xmlns.jcp.org/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/persistence http://xmlns.jcp.org/xml/ns/persistence/persistence_2_2.xsd">
<persistence-unit name="hello">
<properties>
<!-- 필수 속성 -->
<property name="javax.persistence.jdbc.driver" value="org.h2.Driver"/>
<property name="javax.persistence.jdbc.user" value="sa"/>
<property name="javax.persistence.jdbc.password" value=""/>
<property name="javax.persistence.jdbc.url" value="jdbc:h2:tcp://localhost/~/test"/>
<property name="hibernate.dialect" value="org.hibernate.dialect.H2Dialect"/>
<!-- 옵션 -->
<property name="hibernate.show_sql" value="true"/>
<property name="hibernate.format_sql" value="true"/>
<property name="hibernate.use_sql_comments" value="10"/>
<property name="hibernate.hbm2ddl.auto" value="create" />
</properties>
</persistence-unit>
</persistence>

Answer 1

您忘记使用entityManager来persist您的新实体。因此，jpa不知道新实体，也不会保存任何内容。只要加上:em.persist(movie);

Answer 2

您提供的屏幕截图，结合<property name="hibernate.hbm2ddl.auto" value="create" />，表明您在第一次运行应用程序时还没有完成创建实体类。现在，如果您使用hibernate.hbm2ddl.auto = create，并且已经在H2中存在模式，即使您添加了一个或多个实体类，它也不会更新模式。

社区文档建议您使用hibernate.hbm2ddl.auto = update以便在应用程序运行时更新模式。

请注意，根据这个帖子，在生产环境中使用update是不安全的。

尽管Hibernate团队尽了最大的努力，但是在生产环境中您还是不能依赖自动更新。编写自己的补丁，与DBA一起检查，测试，然后手动应用。

理论上，如果hbm2ddl更新在开发中工作，它也应该在生产中工作。但在现实中，情况并非总是如此。

我希望这对你有帮助。