使用hibernate注释在Java中映射子类列表

Question

I have a problem with mapping a list of subclasses:
Model situation - I have an abstract class:

@Entity
@Inheritance(strategy=InheritanceType.SINGLE_TABLE)
@DiscriminatorColumn(
        name="shapeType",
        discriminatorType=DiscriminatorType.STRING
    )
public abstract class Shape{
    @Id
    @GeneratedValue(strategy=GenerationType.IDENTITY)
    protected Long id;

    @Column(name="owner_id")
    private Long ownerId;

    @ManyToOne
    @JoinColumn(updatable=false, insertable=false, name="owner_id")
    private Owner owner;
}

and its subclasses:

@Entity
@DiscriminatorValue(value="triangel")
public class Triangel extends Shape {
}

and:

@Entity
@DiscriminatorValue(value="circle")
public class Circle extends Shape {
}

Then, I have a class Owner , which has a list of subclasses:

@Entity
public class Owner {
    @Id
    @GeneratedValue(strategy=GenerationType.IDENTITY)
    private Long id;

    @OneToMany(fetch = FetchType.LAZY, mappedBy = "owner", targetEntity=Shape.class)
    private List<Triangel> triangels;

    @OneToMany(fetch = FetchType.LAZY, mappedBy = "owner", targetEntity=Shape.class)
    private List<Circle> circles;
}

When I loop over the triangel list:

for(Object triangel: owner.getTriangels()){ //Using Triangel as a type throws ClassCastException
    logger.info(triangel.toString());
}

it iterates all shapes objects, not just triangel objects. It seems to me, that hibernate ignores DiscriminatorColumn during the selection subclasses in that situation.

Mind, that without specification targetEntity as Shape.class in @OneToMany , my application did not even start and had some problem with mapping initialization.

Configuration from pom.xml:

<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>5.1.34</version>
    <scope>provided</scope>
</dependency>
<dependency>
    <groupId>org.hibernate</groupId>
    <artifactId>hibernate-core</artifactId>
    <version>4.3.7.Final</version>
</dependency>
<dependency>
    <groupId>org.hibernate.javax.persistence</groupId>
    <artifactId>hibernate-jpa-2.1-api</artifactId>
    <version>1.0.0.Final</version>
</dependency>
 <dependency>
    <groupId>org.eclipse.persistence</groupId>
    <artifactId>javax.persistence</artifactId>
    <version>2.1.0</version>
    <scope>provided</scope>
</dependency>
<dependency>
    <groupId>commons-dbcp</groupId>
    <artifactId>commons-dbcp</artifactId>
    <version>1.2.2</version>
    <scope>provided</scope>
</dependency>

How am I supposed to do correct mapping configuration of that design?

Answer 1

最近在Hibernate 5.2.7中修复了这个问题： https ： //hibernate.atlassian.net/browse/HHH-11375