Question

我需要从MainEntity中的包中删除SubEntity。

此SubEntity与其他实体有另一种关系。

模型如下：

MainEntity：

@Data
@EqualsAndHashCode(of = "idNum")
@Entity
@Table(name = "MAIN_TABLE")
public class MainEntity implements Serializable {

    @Id
    @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "idNum")
    @SequenceGenerator(name = "idNum", sequenceName = "id_num", allocationSize = 1)
    @Column(name="ID_NUM")
    private Long idNum;

    @OneToMany(mappedBy = "mainEntity", cascade = CascadeType.ALL, orphanRemoval = true)
    private List<SubEntity> subEntities = new ArrayList<>();

    public void addSubEntity(SubEntity subEntity) {
        subEntity.setMainEntity(this);
        subEntities.add(subEntity);
    }

    public void removeSubEntity(SubEntity subEntity) {
        subEntity.setMainEntity(null);
        subEntities.remove(subEntity);
    }


}

子实体：

@Data
@EqualsAndHashCode(of = "subIdNum")
@ToString(exclude = "mainEntity")
@Entity
@Table(name = "SUB_TABLE")
public class SubEntity implements Serializable {

    @Id
    @Column(name = "SUB_ID")
    @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "subIdNumSequence")
    @SequenceGenerator(name = "subIdNumSequence", sequenceName = "SEQ_SUB_ID", allocationSize = 1)
    private Long subIdNum;

    @Column(name = "IND_NUM")
    private String indNum;

    @Column(name = "FAMILY_IDENTIFIER")
    private String familyIdentifier;

    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "ID_NUM")
    private MainEntity mainEntity;

    @OneToMany(mappedBy = "subEntity", cascade = CascadeType.ALL, orphanRemoval = true)
    private List<SubSubEntity> subSubEntities = new ArrayList<>();

    @OneToMany(mappedBy = "subEntity", cascade = CascadeType.ALL, orphanRemoval = true)
    private List<AnotherSubSubEntity> anotherSubSubEntities = new ArrayList<>();

}

SubSubEntity：

@Entity
@Data
@ToString(exclude = "subEntity")
@EqualsAndHashCode(of = {"idNum", "code", "indNum" })
@Table(name = "SUB_SUB_TABLE")
@IdClass(SubSubEntity.SubSubEntityId.class)
public class SubSubEntity implements Serializable {

    @Getter
    @Id
    @Column(name = "ID_NUM", insertable = false, updatable = false)
    private Long idNum;

    @Id
    @Column(name = "CODE")
    private String code;

    @Getter
    @Id
    @Column(name = "IND_NUM", insertable = false, updatable = false)
    private String indNum;

    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumns({
            @JoinColumn(name = "ID_NUM", referencedColumnName = "ID_NUM"),
            @JoinColumn(name = "IND_NUM", referencedColumnName = "IND_NUM")
    })
    @Id
    private SubEntity subEntity;

    public void setSubEntity(SubEntity subEntity) {
        idNum = Optional.ofNullable(subEntity).map(SubEntity::getMainEntity).map(MainEntity::getIdNum).orElse(null);
        code = Optional.ofNullable(subEntity).map(SubEntity::getIndNum).orElse(null);
        this.subEntity = subEntity;
    }

    @Data
    @AllArgsConstructor
    @NoArgsConstructor
    public static class SubSubEntityId implements Serializable {

        private Long idNum;

        private String code;

        private String indNum;

    }


}

AnotherSubSubEntity：

@Entity
@Data
@ToString(exclude = "subEntity")
@EqualsAndHashCode(of = {"idNum", "person", "sourceCode"})
@Table(name = "ANOTHER_SUB_SUB_TABLE")
@IdClass(AnotherSubSubEntity.AnotherSubSubEntityId.class)
public class AnotherSubSubEntity implements Serializable {

    @Getter
    @Id
    @Column(name = "ID_NUM", insertable = false, updatable = false)
    private Long idNum;

    @Getter
    @Id
    @Column(name = "PERSON", insertable = false, updatable = false)
    private String person;

    @Id
    @Column(name = "SOURCE_CODE")
    private String sourceCode;

    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumns({
            @JoinColumn(name = "ID_NUM", referencedColumnName = "ID_NUM", insertable = false, updatable = false),
            @JoinColumn(name = "PERSON", referencedColumnName = "FAMILY_IDENTIFIER", insertable = false, updatable = false)
    })
    @Id
    private SubEntity subEntity;

    public void setSubEntity(SubEntity subEntity) {
        idNum = Optional.ofNullable(subEntity).map(SubEntity::getMainEntity).map(MainEntity::getIdNum).orElse(null);
        person = Optional.ofNullable(subEntity).map(SubEntity::getFamilyIdentifier).orElse(null);
        this.subEntity = subEntity;
    }

    @Data
    @AllArgsConstructor
    @NoArgsConstructor
    public static class AnotherSubSubEntityId implements Serializable {

        private Long idNum;

        private String person;

        private String sourceCode;

    }

}

此测试的架构和数据是（我正在运行嵌入式hsql数据库）：

SET DATABASE SQL SYNTAX ORA TRUE;

CREATE TABLE MAIN_TABLE(
  "ID_NUM" NUMBER,
  CONSTRAINT "PK_MAIN_TABLE" PRIMARY KEY ("ID_NUM")
);

CREATE SEQUENCE SEQ_SUB_ID AS INTEGER START WITH 12345;
CREATE TABLE SUB_TABLE(
  "ID_NUM" NUMBER NOT NULL,
  "SUB_ID" NUMBER(15,0) NOT NULL ,
    "FAMILY_IDENTIFIER" VARCHAR2(15 BYTE),
    "IND_NUM" VARCHAR2(10 BYTE),
    CONSTRAINT "PK_SUB_TABLE" PRIMARY KEY ("SUB_ID"),
    CONSTRAINT "FK_SUB_TABLE_1" FOREIGN KEY ("ID_NUM") REFERENCES "MAIN_TABLE" ("ID_NUM")
);

CREATE TABLE SUB_SUB_TABLE(
  "ID_NUM" NUMBER,
  "CODE" VARCHAR2(5 BYTE),
  "IND_NUM" VARCHAR2(10 BYTE),
  CONSTRAINT "PK_SUB_SUB_TABLE" PRIMARY KEY ("ID_NUM", "CODE", "IND_NUM")
);

CREATE TABLE "ANOTHER_SUB_SUB_TABLE"(
  "ID_NUM" NUMBER,
    "PERSON" VARCHAR2(1 BYTE),
    "SOURCE_CODE" VARCHAR2(5 BYTE),
    CONSTRAINT "PK_ANOTHER_SUB_SUB_TABLE" PRIMARY KEY ("ID_NUM", "PERSON", "SOURCE_CODE"),
    CONSTRAINT "FK_ANOTHER_SUB_SUB_TABLE_1" FOREIGN KEY ("ID_NUM") REFERENCES "MAIN_TABLE" ("ID_NUM")
);


INSERT INTO MAIN_TABLE(ID_NUM) VALUES (99427);
INSERT INTO SUB_TABLE(ID_NUM, SUB_ID, FAMILY_IDENTIFIER, IND_NUM) VALUES (99427, 1, 'A', '123A');
INSERT INTO SUB_TABLE(ID_NUM, SUB_ID, FAMILY_IDENTIFIER, IND_NUM) VALUES (99427, 2, 'S', '321A');
INSERT INTO SUB_SUB_TABLE(ID_NUM, CODE, IND_NUM) VALUES (99427, 'CODE1', '123A');

如果我运行测试用例：

@RunWith(SpringRunner.class)
@SpringBootTest
@Transactional
public class MainRepoTest {

    @Autowired
    private MainRepo mainRepo;


    @Test
    public void testFind() {
        mainRepo.findAll();
    }

    @Test
    public void deleteSubEntity() {
        MainEntity mainEntity = mainRepo.findOne(99427L);
        Optional<SubEntity> subEntityToRemove =  mainEntity.getSubEntities().stream().filter(subEntity -> "123A".equals(subEntity.getIndNum())).findFirst();
        if(subEntityToRemove.isPresent()) {
//            System.out.println(subEntityToRemove.get());
            mainEntity.removeSubEntity(subEntityToRemove.get());
            mainRepo.saveAndFlush(mainEntity);
        }
    }

}

此测试抛出以下异常：

java.lang.NullPointerException
    at org.hibernate.collection.internal.PersistentBag.iterator(PersistentBag.java:278)
    at org.hibernate.type.CollectionType.getElementsIterator(CollectionType.java:229)
    at org.hibernate.type.CollectionType.getElementsIterator(CollectionType.java:219)
    at org.hibernate.engine.spi.CascadingActions.getAllElementsIterator(CascadingActions.java:477)
    at org.hibernate.engine.spi.CascadingActions.access$100(CascadingActions.java:33)
    at org.hibernate.engine.spi.CascadingActions$1.getCascadableChildrenIterator(CascadingActions.java:66)
    at org.hibernate.engine.internal.Cascade.cascadeCollectionElements(Cascade.java:429)
    at org.hibernate.engine.internal.Cascade.cascadeCollection(Cascade.java:363)
    at org.hibernate.engine.internal.Cascade.cascadeAssociation(Cascade.java:326)
    at org.hibernate.engine.internal.Cascade.cascadeProperty(Cascade.java:162)
    at org.hibernate.engine.internal.Cascade.cascade(Cascade.java:111)
    at org.hibernate.event.internal.DefaultDeleteEventListener.cascadeBeforeDelete(DefaultDeleteEventListener.java:336)
    at org.hibernate.event.internal.DefaultDeleteEventListener.deleteEntity(DefaultDeleteEventListener.java:258)
    at org.hibernate.event.internal.DefaultDeleteEventListener.onDelete(DefaultDeleteEventListener.java:143)
    at org.hibernate.internal.SessionImpl.fireDelete(SessionImpl.java:930)
    at org.hibernate.internal.SessionImpl.delete(SessionImpl.java:874)
    at org.hibernate.engine.internal.Cascade.deleteOrphans(Cascade.java:493)
    at org.hibernate.engine.internal.Cascade.cascadeCollectionElements(Cascade.java:466)
    at org.hibernate.engine.internal.Cascade.cascadeCollection(Cascade.java:363)
    at org.hibernate.engine.internal.Cascade.cascadeAssociation(Cascade.java:326)
    at org.hibernate.engine.internal.Cascade.cascadeProperty(Cascade.java:162)
    at org.hibernate.engine.internal.Cascade.cascade(Cascade.java:111)
    at org.hibernate.event.internal.AbstractFlushingEventListener.cascadeOnFlush(AbstractFlushingEventListener.java:150)
    at org.hibernate.event.internal.AbstractFlushingEventListener.prepareEntityFlushes(AbstractFlushingEventListener.java:141)
    at org.hibernate.event.internal.AbstractFlushingEventListener.flushEverythingToExecutions(AbstractFlushingEventListener.java:74)
    at org.hibernate.event.internal.DefaultFlushEventListener.onFlush(DefaultFlushEventListener.java:38)
    at org.hibernate.internal.SessionImpl.flush(SessionImpl.java:1282)
    at org.hibernate.jpa.spi.AbstractEntityManagerImpl.flush(AbstractEntityManagerImpl.java:1300)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.springframework.orm.jpa.SharedEntityManagerCreator$SharedEntityManagerInvocationHandler.invoke(SharedEntityManagerCreator.java:298)
    at com.sun.proxy.$Proxy79.flush(Unknown Source)
    at org.springframework.data.jpa.repository.support.SimpleJpaRepository.flush(SimpleJpaRepository.java:555)
    at org.springframework.data.jpa.repository.support.SimpleJpaRepository.saveAndFlush(SimpleJpaRepository.java:523)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.executeMethodOn(RepositoryFactorySupport.java:513)
    at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.doInvoke(RepositoryFactorySupport.java:498)
    at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.invoke(RepositoryFactorySupport.java:475)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
    at org.springframework.data.projection.DefaultMethodInvokingMethodInterceptor.invoke(DefaultMethodInvokingMethodInterceptor.java:56)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
    at org.springframework.transaction.interceptor.TransactionInterceptor$1.proceedWithInvocation(TransactionInterceptor.java:99)
    at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:282)
    at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:96)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
    at org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.invoke(PersistenceExceptionTranslationInterceptor.java:136)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
    at org.springframework.data.jpa.repository.support.CrudMethodMetadataPostProcessor$CrudMethodMetadataPopulatingMethodInterceptor.invoke(CrudMethodMetadataPostProcessor.java:133)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
    at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:92)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
    at org.springframework.data.repository.core.support.SurroundingTransactionDetectorMethodInterceptor.invoke(SurroundingTransactionDetectorMethodInterceptor.java:57)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
    at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:213)
    at com.sun.proxy.$Proxy81.saveAndFlush(Unknown Source)
    at com.example.repo.MainRepoTest.deleteSubEntity(MainRepoTest.java:35)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
    at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
    at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
    at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
    at org.springframework.test.context.junit4.statements.RunBeforeTestMethodCallbacks.evaluate(RunBeforeTestMethodCallbacks.java:75)
    at org.springframework.test.context.junit4.statements.RunAfterTestMethodCallbacks.evaluate(RunAfterTestMethodCallbacks.java:86)
    at org.springframework.test.context.junit4.statements.SpringRepeat.evaluate(SpringRepeat.java:84)
    at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:252)
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:94)
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
    at org.springframework.test.context.junit4.statements.RunBeforeTestClassCallbacks.evaluate(RunBeforeTestClassCallbacks.java:61)
    at org.springframework.test.context.junit4.statements.RunAfterTestClassCallbacks.evaluate(RunAfterTestClassCallbacks.java:70)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.run(SpringJUnit4ClassRunner.java:191)
    at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
    at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68)
    at com.intellij.rt.execution.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:47)
    at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:242)
    at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:70)

但是，如果我取消注释从SubEntity输出toString的行正常工作。我认为是因为当我删除SubEntity时，懒惰的集合没有初始化。有没有一种优雅的方法可以在Spring Data Jpa / Hibernate中跳过这个错误？

Answer 1

是的，这是关于延迟初始化的。子实体的集合中填充了对象，这些对象实际上只包含以后能够加载它们的信息（如id）。一旦hibernate会话关闭 - 对象被分离，并且您的调用toString失败并出现异常。这正是您的代码中发生的事情，因此要解决您有两个选择：

在Hibernate会话关闭之前调用toString，然后Hibernate将填充对象（调用数据库）。（较受欢迎）
使用渴望的初始化而不是懒惰。这很容易实现，但可能导致高负载。

我认为@Transactional对你的测试方法应该阻止Hibernate会话关闭，但似乎不会发生。它可能是你的repo mainRepo.findOne方法，包含@Transactional。

Answer 2

如果您可以使用this test case template针对最新版本的Hibernate复制它（例如5.2.13）。那么你应该打开一个Jira问题。

使用@ManyToOne将子实体删除到其他实体时出现NullPointerException

2 个答案: