Spring LazyInitializatoinException

今天做project创建了一个新的类A，这个新类包含了一个另外一个类B的Set。B类包含了另外一个C类的集合。。。

public class A{

@Id

int id;

@OneToMany(fetch=FetchType.Lazy)

Set<B> bInstances;


public Set<B> getBInstances(){

return bInstances;

}

}


public class B{

@Id

int id;

@OneToMany(fetch=FetchType.Lazy)

Set<C> cInstances;

}

I define a get function with A's aId and B's bId as input parameters in A's facade and it should return B's instance with the exact bId in A's instance with aId.

@Component
public class AFacade{
@Autowired
AService aService;
public B getBInstance(int aId, int bId){
     return aService.getBInstance(aId, bId);
}

In A's Service class

@Component
public class AService{

@Autowired
ADao aDao;

@Transactional
public A getAInstance(int aId, int bId){
     for(B b: aDao.getAInstance(aId).getBInstances()){
         if( b.getId()==bId){
             return b;
          }
     }
     return null;
}
}

With the code above, I always get the LazyInitializationException. Finally, I figure out the reason. The Transaction ends after AService.getAInstance returns. To fix it, I should move the @Transactioanl annotation to the facade class's getBInstance function.