java - Spring Data findOne() NullPointerException

Question

我认为我缺少一些核心概念，因为我遇到了几个问题，但让我们从这个开始:当具有订阅的用户保存在数据库中时我尝试使用 findOne(id) 获取它，我得到 NullPointerException。我尝试深入调试生成的代码，似乎由于某种原因调用了 Subscription 对象的 hashCode()，而且由于不清楚的原因，该对象只有一个 id 设置和所有其他属性都是 null，但因为它们(可能)通过调用自己的 hashCode() 来参与 hashCode() 方法，我得到这个异常。

所以基本上我想要的是用户成为许多社区的一部分，在每个社区中他都可以创建对其内容的订阅。当我第一次调用 SubscriptionController 时，一切都很顺利，它创建了 User、Subscription 和 Community，我可以看到它们在数据库中，一切都很好。但是当我在 UserSerivce 中调用 UserRepository.findOne()(即 CrudRepository)时，我得到了异常。

我已经尝试解决这个问题两周了，但没有成功，所以我真的希望有人能花一些时间帮助我解决这个问题。 以下是类(class):

用户:

@Entity
@Data
@NoArgsConstructor
public class User {
    @Column(nullable = false)
    @Id
    private Integer id;

    @OneToMany(mappedBy = "user", fetch = FetchType.EAGER, cascade = CascadeType.ALL)
    @JsonIgnore
    Set<Subscription> subscriptions;

    @OneToMany(fetch = FetchType.EAGER, cascade = CascadeType.ALL)
    @JoinTable(
            joinColumns = {@JoinColumn(name = "user_id", referencedColumnName = "id")},
            inverseJoinColumns = {@JoinColumn(name = "payment_id", referencedColumnName = "id", unique = true)}
    )
    @JsonIgnore
    Set<Payment> payments;

    public User(Integer userId) {
        this.id = userId;
    }
}

订阅:

@Entity
@Data
@NoArgsConstructor
public class Subscription {
    @Column
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @JsonIgnore
    private Integer id;

    @ManyToOne(cascade = {CascadeType.MERGE, CascadeType.REFRESH})
    @JoinColumn(name = "user_id", nullable = false)
    private User user;

    @ManyToOne(cascade = {CascadeType.MERGE, CascadeType.REFRESH})
    @JoinColumn(name = "community_id", nullable = false)
    private Community community;

    @Column(nullable = false)
    private Boolean isActive;

    @Column(nullable = false)
    private Date endDate;

    @OneToMany(fetch = FetchType.EAGER, cascade = CascadeType.ALL)
    @JoinTable(
            joinColumns = {@JoinColumn(name = "subscription_id", referencedColumnName = "id")},
            inverseJoinColumns = {@JoinColumn(name = "payment_id", referencedColumnName = "id", unique = true)}
    )
    private Set<Payment> payments;

    public Subscription(User user, Community community, Boolean isActive) {
        this.user = user;
        this.community = community;
        this.isActive = isActive;
        this.endDate = new Date();
    }
}

社区:

@Data
@Entity
@NoArgsConstructor
public class Community {
    @Column(nullable = false)
    @Id
    private Integer id;

    @OneToMany(mappedBy = "community", fetch = FetchType.LAZY, cascade = {CascadeType.MERGE, CascadeType.REFRESH})
    @JsonIgnore
    private Set<Subscription> subscriptions;

    public Community(Integer communityId) {
        this.id = communityId;
    }
}

我还为他们每个人提供服务:

用户服务:

@Service
public class UserService implements IService<User> {
    @Autowired
    private UserRepository userRepository;

    @Transactional
    public User get(@NotNull Integer userId) {
        User user = userRepository.findOne(userId);
        if (user == null)
            return userRepository.save(new User(userId));
        return user;
    }

    @Override
    public User save(@Valid User user) {
        return userRepository.save(user);
    }
}

订阅服务:

@Service
public class SubscriptionService implements IService<Subscription> {
    @Autowired
    SubscriptionRepository subscriptionRepository;
    @Autowired
    PaymentRepository paymentRepository;

    @Override
    public Subscription get(@NotNull Integer id) {
        return subscriptionRepository.findOne(id);
    }

    public Subscription getByUserAndCommunity(@Valid User user, @Valid Community community) {
        Subscription subscription = subscriptionRepository.findByUserAndCommunity(user, community);
        if (subscription != null)
            return subscription;
        subscription = new Subscription(user, community, false);
        return subscriptionRepository.save(subscription);
    }

    @Transactional
    public Subscription activate(@Valid Subscription subscription, @Valid Payment payment, @Future Date endDate) {
        paymentRepository.save(payment);
        Set<Payment> payments = subscription.getPayments();
        if (payments == null)
            payments = new HashSet<>();
        payments.add(payment);
        subscription.setEndDate(endDate);
        subscription.setIsActive(true);
        return subscriptionRepository.save(subscription);
    }

    @Override
    public Subscription save(@Valid Subscription e) {
        return subscriptionRepository.save(e);
    }
}

和社区服务:

@Service
public class CommunityService implements IService<Community> {
    @Autowired
    private CommunityRepository communityRepository;

    @Override
    @Transactional
    public Community get(@NotNull Integer id) {
        Community community = communityRepository.findOne(id);
        if (community == null)
            return communityRepository.save(new Community(id));
        return community;
    }

    @Override
    public Community save(@Valid Community community) {
        return communityRepository.save(community);
    }
}

Controller :

@RestController
public class SubscriptionController {
    @Autowired
    private SubscriptionService subscriptionService;
    @Autowired
    private CommunityService communityService;
    @Autowired
    private PaymentService paymentService;

    @PostMapping("/subscribe")
    public ResponseEntity<Subscription> subscribe(@RequestParam("communityId") Integer communityId, @RequestBody @Valid Payment payment) {
        if(!paymentService.checkPayment(payment))
            return ResponseEntity
                    .status(HttpStatus.BAD_REQUEST)
                    .body(null);

        VkAuthentication vkAuthentication = (VkAuthentication) SecurityContextHolder.getContext().getAuthentication();
        User user = vkAuthentication.getUser();

        Community community = communityService.get(communityId);
        Subscription subscription = subscriptionService.getByUserAndCommunity(user, community);

        Calendar calendar = Calendar.getInstance();
        Date newEndDate = DateUtils.addDays(new Date(), calendar.getActualMaximum(Calendar.DAY_OF_MONTH));

        subscription = subscriptionService.activate(subscription, payment, newEndDate);
        return ResponseEntity
                .status(HttpStatus.OK)
                .body(subscription);
    }
}

这是一些堆栈跟踪:

java.lang.NullPointerException: null
    at org.hibernate.engine.internal.StatefulPersistenceContext.getLoadedCollectionOwnerOrNull(StatefulPersistenceContext.java:786) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final]
    at org.hibernate.event.spi.AbstractCollectionEvent.getLoadedOwnerOrNull(AbstractCollectionEvent.java:58) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final]
    at org.hibernate.event.spi.InitializeCollectionEvent.<init>(InitializeCollectionEvent.java:22) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final]
    at org.hibernate.internal.SessionImpl.initializeCollection(SessionImpl.java:1989) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final]
    at org.hibernate.collection.internal.AbstractPersistentCollection$4.doWork(AbstractPersistentCollection.java:570) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final]
    at org.hibernate.collection.internal.AbstractPersistentCollection.withTemporarySessionIfNeeded(AbstractPersistentCollection.java:252) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final]
    at org.hibernate.collection.internal.AbstractPersistentCollection.initialize(AbstractPersistentCollection.java:566) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final]
    at org.hibernate.collection.internal.AbstractPersistentCollection.read(AbstractPersistentCollection.java:135) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final]
    at org.hibernate.collection.internal.PersistentSet.hashCode(PersistentSet.java:430) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final]
    at zhiyest.subscriptionsbackend.domain.User.hashCode(User.java:14) ~[classes/:na]
    at zhiyest.subscriptionsbackend.domain.Subscription.hashCode(Subscription.java:15) ~[classes/:na]
    at java.util.HashMap.hash(HashMap.java:338) ~[na:1.8.0_111]
    at java.util.HashMap.put(HashMap.java:611) ~[na:1.8.0_111]
    at java.util.HashSet.add(HashSet.java:219) ~[na:1.8.0_111]
    at java.util.AbstractCollection.addAll(AbstractCollection.java:344) ~[na:1.8.0_111]
    at org.hibernate.collection.internal.PersistentSet.endRead(PersistentSet.java:327) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final]
    at org.hibernate.engine.loading.internal.CollectionLoadContext.endLoadingCollection(CollectionLoadContext.java:234) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final]
    at org.hibernate.engine.loading.internal.CollectionLoadContext.endLoadingCollections(CollectionLoadContext.java:221) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final]
    at org.hibernate.engine.loading.internal.CollectionLoadContext.endLoadingCollections(CollectionLoadContext.java:194) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final]
    at org.hibernate.loader.plan.exec.process.internal.CollectionReferenceInitializerImpl.endLoading(CollectionReferenceInitializerImpl.java:154) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final]
    at org.hibernate.loader.plan.exec.process.internal.AbstractRowReader.finishLoadingCollections(AbstractRowReader.java:249) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final]
    at ...

我什至不明白为什么它在 User 的 findOne() 时调用 Subscription.hashCode()...

更新:

at org.springframework.data.repository.core.support.SurroundingTransactionDetectorMethodInterceptor.invoke(SurroundingTransactionDetectorMethodInterceptor.java:57) ~[spring-data-commons-1.13.4.RELEASE.jar:na]
    ... 
    at zhiyest.subscriptionsbackend.logging.Logger.logAround(Logger.java:29) ~[classes/:na]
    ...
    at zhiyest.subscriptionsbackend.services.UserService$$EnhancerBySpringCGLIB$$6e00bac4.get(<generated>) ~[classes/:na]
    at zhiyest.subscriptionsbackend.security.VkAuthenticationProvider.authenticate(VkAuthenticationProvider.java:23) ~[classes/:na]
    at zhiyest.subscriptionsbackend.security.VkAuthenticationProvider$$FastClassBySpringCGLIB$$24f3d662.invoke(<generated>) ~[classes/:na]
    ...
    at zhiyest.subscriptionsbackend.security.VkAuthenticationProvider$$EnhancerBySpringCGLIB$$4d8d8001.authenticate(<generated>) ~[classes/:na]
    at org.springframework.security.authentication.ProviderManager.authenticate(ProviderManager.java:174) ~[spring-security-core-4.2.3.RELEASE.jar:4.2.3.RELEASE]
    at org.springframework.security.authentication.ProviderManager.authenticate(ProviderManager.java:199) ~[spring-security-core-4.2.3.RELEASE.jar:4.2.3.RELEASE]
    at org.springframework.security.access.intercept.AbstractSecurityInterceptor.authenticateIfRequired(AbstractSecurityInterceptor.java:354) ~[spring-security-core-4.2.3.RELEASE.jar:4.2.3.RELEASE]
    at org.springframework.security.access.intercept.AbstractSecurityInterceptor.beforeInvocation(AbstractSecurityInterceptor.java:229) ~[spring-security-core-4.2.3.RELEASE.jar:4.2.3.RELEASE]
    ...

Answer 1

我猜问题出在@Data。

此 lombok 注释是递归依赖项(toString() 和 hashcode())的原因。尝试使用 @Getter 和 @Setter 而不是 @Data。

希望对您有所帮助。