如何使用metamodel.MapAttribute？我想从Map获取值，但我不知道如何？我们的想法是了解校准台上的所有仪表。
public class Calibration_ {
public static volatile javax.persistence.metamodel.MapAttribute<Calibration,Integer, Meter> positionsMeters;
}
我有这种地图属性，以了解仪表在校准台上的位置
@Entity
public class Calibration extends AbstractEntity implements Serializable {
private Map<Integer, Meter> positionsMeters;
….
}
我试图以这种方式获取值，但它不起作用：
final QueryData<Calibration> queryData = new QueryData<>(Calibration.class);
final EntityManagerFactory em = Main.context.getBean(EntityManagerFactory.class);
final CriteriaBuilder builder = em.getCriteriaBuilder();
final Root<Meter> meter= queryData.criteria.from(Meter.class);
final Root<Company> company= queryData.criteria.from(Company.class);
Predicate filter = null;
filter = builder.and(
builder.like(queryData.builder.lower(company.get(Company_.name)),"%" + attribute.toLowerCase() + "%"),
builder.equal(meter.get(Meter_.owner), company),
builder.isMember(meter,builder.values((Map<Integer,Meter>)queryData.root.get(Calibration_.positionsMeters)))
);