如何使用 jpa 从数据库中删除单向、一对一映射

Question

我想从数据库中删除商家表中的行和地址表中的行。商户的表中有address_id。我已经为 Merchant 和 Address 创建了 DAO。如何仅使用实体管理器来做到这一点？我省略了导入、getter 和 setter。似乎只删除了Merchant表中的行，而保留了地址表中的行。任何帮助将不胜感激，谢谢。

每当我删除商家实体时，它都会保留地址id，并且不会删除Address表中相应的地址。我不明白为什么。

@Entity

public class Merchant {

    @Id

    @GeneratedValue(strategy = GenerationType.IDENTITY)

    private int id;

    private String name;

    @OneToOne

    private Address address;

    public Merchant() {

    }

}

public class MerchantDAO {

    protected static EntityManagerFactory emf = Persistence.createEntityManagerFactory("hamzaspersistenceunit");

    public void persist(Merchant merchant) {

        EntityManager em = emf.createEntityManager();

        em.getTransaction().begin();

        em.persist(merchant);

        em.getTransaction().commit();

        em.close();

    }

    public void removeMerchant(Merchant merchant) {

        EntityManager em = emf.createEntityManager();

        em.getTransaction().begin();

        em.remove(em.contains(merchant) ? merchant : em.merge(merchant));

        em.getTransaction().commit();

        em.close();

    }

}

@Entity

public class Address {

    @Id

    @GeneratedValue(strategy = GenerationType.IDENTITY)

    private int id;

    private String name;

    private String streetAddress;

    private String city;

    private String state;

    private String zipCode;

    public Address(String name, String streetAddress, String city, String state, String zipCode) {

        super();

        this.name = name;

        this.streetAddress = streetAddress;

        this.city = city;

        this.state = state;

        this.zipCode = zipCode;

    }

}

public class AddressDAO {

    protected static EntityManagerFactory emf = Persistence.createEntityManagerFactory("hamzaspersistenceunit");

    public AddressDAO() {

    }

    public void persist(Address address) {

        EntityManager em = emf.createEntityManager();

        em.getTransaction().begin();

        em.persist(address);

        em.getTransaction().commit();

        em.close();

    }

Answer 1

尝试使用 注释实体address中的字段。默认情况下，此选项设置为，因此删除操作不会级联到实体。Merchant@OneToOne(orphanRemoval = true)falseAddress更新：此问题的正确解决方案是使用@OneToOne(cascade = CascadeType.REMOVE)