尝试删除实体时出现 java.lang.StackOverflowError

Question

尝试删除实体时，会发生 StackOverflowError。唯一发生这种情况的是当我有一个包含 2 个外键引用的复合键时。我在下面创建了一个最小的示例:

第一个包含 @OneToMany 集合的对象:

@Entity
public class Foo {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private long id;

    @OneToMany(mappedBy = "id.foo", cascade = CascadeType.ALL, orphanRemoval = true)
    private List<Baz> baz;

    // Getters and setters omitted.
}

包含 @OneToMany 引用的第二个对象:

@Entity
public class Bar {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private long id;

    @OneToMany(mappedBy = "id.bar", cascade = CascadeType.ALL, orphanRemoval = true)
    private List<Baz> baz;

    // Getters and setters omitted.
}

包含上述两个对象(Foo 和 Bar)作为复合键的对象:

@Entity
public class Baz {

    @EmbeddedId
    private BazId id;

    // Getters and setters omitted.
}

最后是 Baz 的复合键类:

@Embeddable
public class BazId implements Serializable {

    private static final long serialVersionUID = -8869241450494423817L;

    @ManyToOne
    private Foo foo;

    @ManyToOne
    private Bar bar;

    // Getters and setters omitted
}

当我执行下面的测试时，我得到一个java.lang.StackOverflowError:

// Spring Data JPA Repositories (extend CrudRepository)
@Autowired private FooRepository fooRepository;
@Autowired private BarRepository barRepository;
@Autowired private BazRepository bazRepository;

@Test
public void test() {
    final Foo foo = new Foo();
    fooRepository.save(foo);

    final Bar bar = new Bar();
    barRepository.save(bar);

    final Baz baz = new Baz(new BazId(foo, bar));
    bazRepository.save(baz);

    foo.getBaz().add(baz);
    bar.getBaz().add(baz);

    // These two deletes cause the StackOverflowError
    fooRepository.delete(foo);
    barRepository.delete(bar);
}

我尝试过的:

• 重写equals(Object o)、toString() 和hashCode()。

除了完全重做我的映射之外，我不知道还能尝试什么。我需要以这种方式设置映射，就像在我的实际项目中一样，我有一个 User 跟随一个 Business，因此这需要是两个实体之间的组合键。为什么这会导致无限递归？

编辑

堆栈跟踪是否有帮助(部分。整个事情不适合):

java.lang.StackOverflowError
    at org.apache.tomcat.jdbc.pool.ProxyConnection.invoke(ProxyConnection.java:131)
    at org.apache.tomcat.jdbc.pool.JdbcInterceptor.invoke(JdbcInterceptor.java:108)
    at org.apache.tomcat.jdbc.pool.DisposableConnectionFacade.invoke(DisposableConnectionFacade.java:81)
    at com.sun.proxy.$Proxy73.prepareStatement(Unknown Source)
    at org.hibernate.engine.jdbc.internal.StatementPreparerImpl$5.doPrepare(StatementPreparerImpl.java:146)
    at org.hibernate.engine.jdbc.internal.StatementPreparerImpl$StatementPreparationTemplate.prepareStatement(StatementPreparerImpl.java:172)
    at org.hibernate.engine.jdbc.internal.StatementPreparerImpl.prepareQueryStatement(StatementPreparerImpl.java:148)
    at org.hibernate.loader.Loader.prepareQueryStatement(Loader.java:1929)
    at org.hibernate.loader.Loader.executeQueryStatement(Loader.java:1898)
    at org.hibernate.loader.Loader.executeQueryStatement(Loader.java:1876)
    at org.hibernate.loader.Loader.doQuery(Loader.java:919)
    at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:336)
    at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:306)
    at org.hibernate.loader.Loader.loadEntity(Loader.java:2204)
    at org.hibernate.loader.entity.AbstractEntityLoader.load(AbstractEntityLoader.java:60)
    at org.hibernate.loader.entity.AbstractEntityLoader.load(AbstractEntityLoader.java:50)
    at org.hibernate.persister.entity.AbstractEntityPersister.load(AbstractEntityPersister.java:3956)
    at org.hibernate.event.internal.DefaultLoadEventListener.loadFromDatasource(DefaultLoadEventListener.java:508)
    at org.hibernate.event.internal.DefaultLoadEventListener.doLoad(DefaultLoadEventListener.java:478)
    at org.hibernate.event.internal.DefaultLoadEventListener.load(DefaultLoadEventListener.java:219)
    at org.hibernate.event.internal.DefaultLoadEventListener.proxyOrLoad(DefaultLoadEventListener.java:278)
    at org.hibernate.event.internal.DefaultLoadEventListener.doOnLoad(DefaultLoadEventListener.java:121)
    at org.hibernate.event.internal.DefaultLoadEventListener.onLoad(DefaultLoadEventListener.java:89)
    at org.hibernate.internal.SessionImpl.fireLoad(SessionImpl.java:1129)
    at org.hibernate.internal.SessionImpl.internalLoad(SessionImpl.java:1022)
    at org.hibernate.type.EntityType.resolveIdentifier(EntityType.java:632)
    at org.hibernate.type.EntityType.resolve(EntityType.java:424)
    at org.hibernate.type.ComponentType.resolve(ComponentType.java:687)
    at org.hibernate.loader.Loader.extractKeysFromResultSet(Loader.java:848)
    at org.hibernate.loader.Loader.getRowFromResultSet(Loader.java:714)
    at org.hibernate.loader.Loader.processResultSet(Loader.java:972)
    at org.hibernate.loader.Loader.doQuery(Loader.java:930)
    at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:336)
    at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:306)
    at org.hibernate.loader.Loader.loadEntity(Loader.java:2204)
    at org.hibernate.loader.entity.AbstractEntityLoader.load(AbstractEntityLoader.java:60)
    at org.hibernate.loader.entity.AbstractEntityLoader.load(AbstractEntityLoader.java:50)
    at org.hibernate.persister.entity.AbstractEntityPersister.load(AbstractEntityPersister.java:3956)
    at org.hibernate.event.internal.DefaultLoadEventListener.loadFromDatasource(DefaultLoadEventListener.java:508)
    at org.hibernate.event.internal.DefaultLoadEventListener.doLoad(DefaultLoadEventListener.java:478)
    at org.hibernate.event.internal.DefaultLoadEventListener.load(DefaultLoadEventListener.java:219)
    at org.hibernate.event.internal.DefaultLoadEventListener.proxyOrLoad(DefaultLoadEventListener.java:278)
    at org.hibernate.event.internal.DefaultLoadEventListener.doOnLoad(DefaultLoadEventListener.java:121)
    at org.hibernate.event.internal.DefaultLoadEventListener.onLoad(DefaultLoadEventListener.java:89)
    at org.hibernate.internal.SessionImpl.fireLoad(SessionImpl.java:1129)
    at org.hibernate.internal.SessionImpl.internalLoad(SessionImpl.java:1022)
    at org.hibernate.type.EntityType.resolveIdentifier(EntityType.java:632)
    at org.hibernate.type.EntityType.resolve(EntityType.java:424)
    at org.hibernate.type.ComponentType.resolve(ComponentType.java:687)
    at org.hibernate.loader.Loader.extractKeysFromResultSet(Loader.java:848)
    at org.hibernate.loader.Loader.getRowFromResultSet(Loader.java:714)
    at org.hibernate.loader.Loader.processResultSet(Loader.java:972)
    at org.hibernate.loader.Loader.doQuery(Loader.java:930)
    at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:336)

Answer 1

在 Foo 和 Bar 内的 Baz 集合上使用 cascade = CascadeType.ALL 会在尝试时导致无限递归删除。删除两个集合上的级联并手动删除 Baz 关系(而不是级联)来解决此问题。