Spring Data findOne（）NullPointerException

时间：2017-09-10 11:57:44

标签： java spring-boot spring-data lombok

我认为我缺少一些核心概念，因为我遇到了几个问题，但让我们从这个问题开始：当User Subscription持续存在于数据库中并尝试获取它时使用findOne(id)，我得到NullPointerException。我尝试在内部生成的代码中进行深度调试，看起来由于某种原因调用hashCode() Subscription个id对象，这也是因为不明原因只有null集，而所有其他属性都是{ {1}}，但是因为他们（可能）通过调用他们自己的hashCode()参与hashCode()方法，所以我得到了这个例外。

基本上我想要的是用户是许多社区的一部分，在每个社区中他都可以创建对其内容的订阅。当我第一次打电话给SubscriptionController时，一切正常，它会创建User，Subscription和Community，我可以在数据库中看到它们，一切都很好。但是当我在UserRepository.findOne()内拨打CrudRepository UserSerivce时 - 我得到了例外。

我一直试图解决这个问题两个星期而且没有运气，所以我真的希望有人可以花一些时间来帮助我。 以下是课程：

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;
    }
}

我也为每个人提供服务：

UserService：

@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);
    }
}

SubscriptionService：

@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);
    }
}

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);
    }
}

控制器：

@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);
    }
}

这里有一些堆栈跟踪：

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 ...

我甚至不明白为什么Subscription.hashCode()为findOne() User时会调用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] ... 。

UPD：

{{1}}

2 个答案:

答案 0 :(得分：3)

我猜这个问题是@Data。

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

我希望它会有所帮助。

答案 1 :(得分：2)

这似乎是某些版本的Hibernate中的错误（请参见下面的第一篇文章）。如果您有一组嵌套的其他Hibernate实体，则在其hashCode（）方法内部访问它们似乎有问题。我通过调试确认了这一点。

您可以手动生成一个哈希/代码等于并删除另一个实体。或者，您也可以在下面的第二篇文章中通过评论建议在Lombok中执行以下操作：

@EqualsAndHashCode(exclude={"subscriptions"})

我之所以说“某物”，是因为我没有足够仔细地阅读您的对象图，以至于看不到应该排除哪个对象。但这是一个简单的解决方案，通常，将对象的辅助内容作为其逻辑标识的一部分是没有意义的。

Hibernate 4.2.20 Object HashCode Method Causing NullPointerException

How do you retrieve nested Sets?

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