Java泛型-多次使用同一通配符

class Factory<X extends Entity,
              T extends Logic<X>, 
              U extends DAO<X>> 
{
}

class Factory<T extends Logic<?>, 
              U extends DAO<?>> 
{
    // Here, the generic method parameter only requires X
    // to be the same bound at method invocation. However,
    // you will \"lose\" that information again when the 
    // Factory is returned.
    public static <X extends Entity,
                   T extends Logic<X>, 
                   U extends DAO<X>> Factory<T, U> createFactory(T logic, U dao)
    {
        return new Factory<T, U>(logic, dao);
    }
}

class Entity{}

interface Logic<T extends Entity> {}

interface DAO<T extends Entity> {}

interface DaoLogic<X extends Entity> {
  DAO<X> getDAO();
  Logic<X> getLogic();
}

class Factory<T extends DaoLogic<? extends Entity>> {}

public class Factory<X extends Entity, T extends Logic<X>, U extends DAO<X>>
{
}