Question

我正在使用hibernate映射生成模式。但由于某种原因，一对一映射无法正确生成。这是我的课程：

@Entity
@Table(name = "resturant")
public class Restaurant {

    private Integer restid;
    private String restaurantName;
    private Foursquare foursquare;

    @Id
    @Column(name = "restid")
    @GeneratedValue(strategy = GenerationType.AUTO)
    public Integer getId() {
        return restid;
    }

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

    @OneToOne(fetch = FetchType.LAZY, mappedBy = "restaurant", cascade = CascadeType.ALL)
    public Foursquare getFoursquare() {
        return foursquare;
    }

    public void setFoursquare(Foursquare foursquare) {
        this.foursquare = foursquare;
    }

    @Column(name = "restname")
    public String getRestaurantName() {
        return restaurantName;
    }

    public void setRestaurantName(String restaurantName) {
        this.restaurantName = restaurantName;
    }

}

和

@Entity
@Table(name = "foursquare")
public class Foursquare {

    private Integer foursquareid;
    private Restaurant restaurant;

    @Id
    @Column(name = "fsid")
    @GeneratedValue(strategy = GenerationType.AUTO)
    public Integer getFoursquareid() {
        return foursquareid;
    }

    public void setFoursquareid(Integer foursquareid) {
        this.foursquareid = foursquareid;
    }

    @OneToOne(fetch = FetchType.LAZY)
    @PrimaryKeyJoinColumn
    public Restaurant getRestaurant() {
        return restaurant;
    }

    public void setRestaurant(Restaurant restaurant) {
        this.restaurant = restaurant;
    }
}

我的hbm文件如下：

<!DOCTYPE hibernate-configuration PUBLIC
    "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
    "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">

<hibernate-configuration>
    <session-factory>

        <!-- You need to complete the configuration here. This is just a sample, 
            you should use a connection pool -->
        <property name="connection.url">jdbc:mysql://localhost:3306/menus3</property>
        <property name="connection.username">root</property>
        <property name="connection.password"></property>
        <property name="connection.driver_class">com.mysql.jdbc.Driver</property>
        <property name="hibernate.jdbc.batch_size">50</property>
        <property name="hibernate.cache.use_second_level_cache">false</property>

        <property name="dialect">org.hibernate.dialect.MySQLDialect</property>

        <property name="show_sql">true</property>
        <property name="hibernate.hbm2ddl.auto">create</property>

        <mapping class="Restaurant" />
        <mapping class="Foursquare" />
    </session-factory>
</hibernate-configuration>

这是我的HibernateUtil类：

import org.hibernate.SessionFactory;
import org.hibernate.cfg.AnnotationConfiguration;

public final class HibernateUtil {

    private static SessionFactory sessionFactory;

    static {
        try {
            sessionFactory = new AnnotationConfiguration().configure()
                    .buildSessionFactory();
        } catch (Throwable ex) {

            throw new ExceptionInInitializerError(ex);
        }
    }

    private HibernateUtil() {

    }

    public static SessionFactory getSessionFactory() {
        return sessionFactory;
    }

}

我正在运行一个简单的类来通过加载配置来生成模式：

public class Test {

    public static void main(String[] args) {

        SessionFactory sessionFactory = HibernateUtil.getSessionFactory();
        Session session = sessionFactory.openSession();
        session.close();
    }
}

这应该在Foursquare表中创建restid的外键，但事实并非如此。 sql看起来像：

Hibernate: drop table if exists foursquare
Hibernate: drop table if exists resturant
Hibernate: create table foursquare (fsid integer not null auto_increment, idinfoursquare varchar(255), primary key (fsid))
Hibernate: create table resturant (restid integer not null auto_increment, restname varchar(255), staddress varchar(255), primary key (restid))

有人能指出为什么一对一的映射没有反映在我的数据库中吗？为什么没有生成外键列？

Answer 1

您使用了@PrimaryKeyJoinColumn。 @PrimaryKeyJoinColumn注释确实表示实体的主键用作关联实体的外键值。所以外键没有生成。要生成外键，您应该删除@PrimaryKeyJoinColumn注释。

@OneToOne(fetch = FetchType.LAZY)
//@PrimaryKeyJoinColumn     Remove this annotation.
public Restaurant getRestaurant() {
    return restaurant;
}

Hibernate一对一映射。架构生成问题

1 个答案: