Hy，我有懒惰的提问问题，并且为什么会发生这种问题。 我有两个问题：
@Entity
@Table(name = "PERSONS")
public class Persons {
...
@OneToMany(mappedBy = "person", cascade = CascadeType.ALL, fetch = FetchType.LAZY)
public List<Cards> cards = new ArrayList<Cards>();
...
}
和
@Entity
@Table(name = "CARDS")
public class Cards {
...
@ManyToOne (fetch = FetchType.EAGER)
@JoinColumn(name = "PERSON_ID")
@JsonBackReference
@OnDelete(action = OnDeleteAction.CASCADE)
private Persons person;
...
}
和人的存储库：
@Repository
@Transactional
public class PersonRepository {
@Autowired
private SessionFactory sessionFactory;
public List<Persons> getAll() {
return getSession().createCriteria(Persons.class).list();
}
protected Session getSession() {
return sessionFactory.getCurrentSession();
}
}
当我尝试获取人物时，我也会为每个人收集所有卡片，但我不想收集这些卡片。我怎么能解决这个问题？
SQL查询：
select
this_.PERSON_ID as PERSON_ID1_10_2_,
this_.CITY_ID as CITY_ID8_10_2_,
this_.EMAIL as EMAIL2_10_2_,
this_.FIRST_NAME as FIRST_NAME3_10_2_,
this_.LAST_NAME as LAST_NAME4_10_2_,
this_.MOBILE_NUMBER as MOBILE_NUMBER5_10_2_,
this_.NICKNAME as NICKNAME6_10_2_,
this_.PASSWORD as PASSWORD7_10_2_,
this_.ROLE_ID as ROLE_ID9_10_2_,
cities2_.CITY_ID as CITY_ID1_5_0_,
cities2_.CITY_NAME as CITY_NAME2_5_0_,
rollers3_.ROLE_ID as ROLE_ID1_11_1_,
rollers3_.ROLE_TYPE as ROLE_TYPE2_11_1_
from
PERSONS this_
inner join
CITIES cities2_
on this_.CITY_ID=cities2_.CITY_ID
left outer join
ROLLERS rollers3_
on this_.ROLE_ID=rollers3_.ROLE_ID
Hibernate:
select
this_.PERSON_ID as PERSON_ID1_10_2_,
this_.CITY_ID as CITY_ID8_10_2_,
this_.EMAIL as EMAIL2_10_2_,
this_.FIRST_NAME as FIRST_NAME3_10_2_,
this_.LAST_NAME as LAST_NAME4_10_2_,
this_.MOBILE_NUMBER as MOBILE_NUMBER5_10_2_,
this_.NICKNAME as NICKNAME6_10_2_,
this_.PASSWORD as PASSWORD7_10_2_,
this_.ROLE_ID as ROLE_ID9_10_2_,
cities2_.CITY_ID as CITY_ID1_5_0_,
cities2_.CITY_NAME as CITY_NAME2_5_0_,
rollers3_.ROLE_ID as ROLE_ID1_11_1_,
rollers3_.ROLE_TYPE as ROLE_TYPE2_11_1_
from
PERSONS this_
inner join
CITIES cities2_
on this_.CITY_ID=cities2_.CITY_ID
left outer join
ROLLERS rollers3_
on this_.ROLE_ID=rollers3_.ROLE_ID
Result set row: 0
` 我用sql查询做错了。
我在appcontroller类中配置logger：
@RequestMapping(value = {"/", "/home"}, method = RequestMethod.GET)
public String homePage(ModelMap model) {
model.addAttribute("greeting", "Welcome to the first page of the project");
List<Persons> personsList = personService.getUsers();
if (Const.DEBUG) {
if (logger.isDebugEnabled()) {
for (Persons persons : personsList) {
logger.debug("Array Card size " + persons.getCards().size() + " for " + persons.getNickname());
for (Cards card : persons.getCards()) {
logger.debug("CardName " + card.getCardName());
}
}
}
}
return "welcome";
}
然后在调试模式下运行项目我在控制台输出文件中得到它：
[DEBUG] 2017-05-02 08:32:46 com.team.mvc.controller.AppController:homePage:55 - Array Card size 0 for Alex
[DEBUG] 2017-05-02 08:32:49 com.team.mvc.controller.AppController:homePage:55 - Array Card size 0 for ui1
[DEBUG] 2017-05-02 08:32:50 com.team.mvc.controller.AppController:homePage:55 - Array Card size 0 for ui2
[DEBUG] 2017-05-02 08:32:50 com.team.mvc.controller.AppController:homePage:55 - Array Card size 1 for vvv
[DEBUG] 2017-05-02 08:32:51 com.team.mvc.controller.AppController:homePage:57 - CardName null
[DEBUG] 2017-05-02 08:32:53 com.team.mvc.controller.AppController:homePage:55 - Array Card size 1 for Sam
[DEBUG] 2017-05-02 08:32:54 com.team.mvc.controller.AppController:homePage:55 - Array Card size 0 for Alex
[DEBUG] 2017-05-02 08:32:54 com.team.mvc.controller.AppController:homePage:57 - CardName null
[DEBUG] 2017-05-02 08:32:55 com.team.mvc.controller.AppController:homePage:55 - Array Card size 0 for Alex
[DEBUG] 2017-05-02 08:32:56 com.team.mvc.controller.AppController:homePage:55 - Array Card size 0 for ui1
[DEBUG] 2017-05-02 08:32:56 com.team.mvc.controller.AppController:homePage:55 - Array Card size 0 for ui1
[DEBUG] 2017-05-02 08:32:56 com.team.mvc.controller.AppController:homePage:55 - Array Card size 0 for 7
[DEBUG] 2017-05-02 08:32:56 com.team.mvc.controller.AppController:homePage:55 - Array Card size 0 for ui2
这意味着用户＆＃34; vvv＆＃34;有一张卡片和懒人取物不能正常工作。
Class PersonService：
@Service
@Transactional
public class PersonService {
...
@Autowired
PersonRepository personRepository;
public List<Persons> getUsers() {
List<Persons> personList = new ArrayList<>();
for (Persons person : personRepository.getAll()) {
if (person.getRole().getRoleType().equals("USER"))
personList.add(person);
}
return personList;
}
...
}
我错在哪里？