java - Hibernate单表继承

Question

我有两个实体 BillingAddress 和 ShippingAddress 映射到具有鉴别器 TYPE 列的表地址。

@Entity
@Table(name = "address")
@Inheritance(strategy = InheritanceType.SINGLE_TABLE)
@DiscriminatorColumn(name = "TYPE",discriminatorType = DiscriminatorType.INTEGER)
@DiscriminatorValue(value = "1")
@NamedQueries({
    @NamedQuery(name = "Shippingaddress.findAll", query = "SELECT s FROM Shippingaddress s")})
public class Shippingaddress  implements Serializable{}

@Entity
@Table(name = "address")
@DiscriminatorValue(value = "2")
@NamedQueries({
    @NamedQuery(name = "Billingaddress.findAll", query = "SELECT b FROM Billingaddress b")})
public class Billingaddress extends Shippingaddress implements Serializable {}

我能够在具有不同 TYPE 值的数据库中成功保存/更新两种地址类型。

我面临的问题是当我按如下方式查询 ADDRESS 表时:

Session session=getCurrentSession();
        Query query=session.createQuery("from Billingaddress where userId.userId=:userId");
        query.setLong("userId", userId);
        billingaddress=(Billingaddress)query.uniqueResult();

这工作正常，但查询 ShippingAddress 会抛出 NonUniqueResult Exception，即我在结果中同时获得 Shippingaddress 和 Billingaddress。请让我知道，我应该做些什么不同的事情。

Session session=getCurrentSession();
        Query query=session.createQuery("from Shippingaddress where userId.userId=:userId");
        query.setLong("userId", userId);
        shippingaddress=(Shippingaddress)query.uniqueResult();

Answer 1

另一种解决方案是创建一个抽象类Address并将父类中的列映射为“insertable = false, updatable = false”

然后您可以在查询中添加类型:

@Entity
@Table(name = "address")
@Inheritance(strategy = InheritanceType.SINGLE_TABLE)
@DiscriminatorColumn(name = "TYPE",discriminatorType = DiscriminatorType.INTEGER)
@NamedQueries({
@NamedQuery(name = "Address.findAll", query = "SELECT s FROM Address s where type = :type")})
public class Address implements Serializable {
    @Column(name="TYPE", insertable=false, updatable=false)
    private Integer type;
}

@Entity
@DiscriminatorValue(value = "1")
@NamedQueries({
@NamedQuery(name = "Shippingaddress.findAll", query = "SELECT s FROM Shippingaddress s")})
public class Shippingaddress  implements Serializable{}

@Entity
@DiscriminatorValue(value = "2")
@NamedQueries({
@NamedQuery(name = "Billingaddress.findAll", query = "SELECT b FROM Billingaddress b")})
public class Billingaddress extends Shippingaddress implements Serializable {}

然后您可以写“from Address where type = 1”与“from Shippingaddress”相同，“from Address”将检索所有行