我有三个班级,分别是国家,州和郊区。每个国家都有很多州,每个州都有许多郊区。
我的休眠是4.2.1.Final。
问题是虽然状态的FetchType定义为EAGER,但我无法检索每个州的郊区。
我也读过这个answer。因为我不想在检索国家的任何时候检索郊区的所有州。所以我认为需要使用标准而不是使用
来覆盖提取策略
@LazyCollection(LazyCollectionOption.FALSE)
国家
@Entity
public class Country {
private List<States> states;
...
public Country(){
this.states = new ArrayList();
}
@OneToMany (cascade = CascadeType.ALL)
public List<States> getStates() {
return states;
}
....
}
国家
@Entity
public class States {
private long id;
private String name;
private List<Suburbs> suburbs;
...
public States(){
this.suburbs = new ArrayList();
}
@OneToMany(cascade = CascadeType.ALL, fetch = FetchType.EAGER)
public List<Suburbs> getSuburbs() {
return suburbs;
}
}
郊区
@Entity
public class Suburbs {
private long id;
private String name;
....
}
代码
Criteria criteria = session.createCriteria(Country.class, "country")
.createAlias("country.states", "states");
ProjectionList pl = Projections.projectionList();
pl.add(Projections.property("states.id").as("id"));
pl.add(Projections.property("states.name").as("name"));
criteria.setProjection(pl);
criteria.setResultTransformer(new
AliasToBeanResultTransformer(States.class));
criteria.add(Restrictions.eq("country.id", id));
List<States> statesList = new ArrayList();
statesList = (List<States>) criteria.list();
System.out.println(">>>"
+ statesList.get(0).getSuburbs().size());
>>>>> returns Zero