java如何用hibernate映射map<Class，AbstractEntity>这样的属性？

Question

Hibernate是否有可能执行以下实体结构

@Entity
public class Person {

    @OneToMany
    private Map<Class<? extends PersonRole>, PersonRole> personRoles;

    public <T extends PersonRole> T getRole(Class<T> roleClass) {
         return roleClass.cast(roles.get(roleClass));
    }

}

@Entity
public abstract class PersonRole {

    @ManyToOne
    private Person person;

}

基本上，Hibernate可以持久化这个映射实体，但无法再从数据库中加载它，以下情况除外：

Exception in thread "main" org.hibernate.HibernateException: null index column for      collection: de.his.cs.sys.hibernate.Person.roles
at org.hibernate.persister.collection.AbstractCollectionPersister.readIndex(AbstractCollectionPersister.java:822)
at org.hibernate.collection.internal.PersistentMap.readFrom(PersistentMap.java:277)
at org.hibernate.loader.Loader.readCollectionElement(Loader.java:1189)
at org.hibernate.loader.Loader.readCollectionElements(Loader.java:804)
at org.hibernate.loader.Loader.getRowFromResultSet(Loader.java:655)
at org.hibernate.loader.Loader.doQuery(Loader.java:854)
at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:293)
at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:263)
at org.hibernate.loader.Loader.loadCollection(Loader.java:2094)
at org.hibernate.loader.collection.CollectionLoader.initialize(CollectionLoader.java:61)

一个解决办法可能是使用“简单”的集合，并用拦截器填充地图，但我希望在没有额外基础设施的情况下实现这一点