有人可以解释，这应该如何实现？
我有一个Parent实体（在底部堆栈跟踪中称为Executor）：
class Parent {
@Id
private int id;
}
我有一个Child（堆栈跟踪中的Param1CK，params3表），其ID为Composite，依赖于“Parent”和“行号”：
@IdClass(ChildID.class)
class Child {
@Id
@ManyToOne
@JoinColumn
private Parent parent;
@Id
@Column
private int id;
}
class ChildID implements Serializable{
private Parent parent;
private int id;
@Override
public int hashCode() {...}
}
父母中的Child集合描述为：
@OneToMany(mappedBy="parent")
@Cascasde(value = CascadeType.ALL)
private List<Child> list = ...;
而这一点似乎被错误地解决了。
当我尝试做一个：
Parent p = new Parent();
p.getList().add(new Child(p)); // with the Parent targeting in the constructor
并执行多次“保存”操作，Hibernate无法解析密钥，并执行一个循环来解析父密钥，该密钥正在解析为stackOverFlow：
Hibernate: select executor0_.id as id1_3_1_, executor0_.parent_id as parent_i2_3_1_, params3x1_.parent_id as parent_i3_6_3_, params3x1_.prop as prop1_6_3_, params3x1_.prop as prop1_6_0_, params3x1_.parent_id as parent_i3_6_0_, params3x1_.value as value2_6_0_ from executor executor0_ left outer join paraaaamsssck params3x1_ on executor0_.id=params3x1_.parent_id where executor0_.id=?
Hibernate: select executor0_.id as id1_3_1_, executor0_.parent_id as parent_i2_3_1_, params3x1_.parent_id as parent_i3_6_3_, params3x1_.prop as prop1_6_3_, params3x1_.prop as prop1_6_0_, params3x1_.parent_id as parent_i3_6_0_, params3x1_.value as value2_6_0_ from executor executor0_ left outer join paraaaamsssck params3x1_ on executor0_.id=params3x1_.parent_id where executor0_.id=?
Hibernate: select executor0_.id as id1_3_1_, executor0_.parent_id as parent_i2_3_1_, params3x1_.parent_id as parent_i3_6_3_, params3x1_.prop as prop1_6_3_, params3x1_.prop as prop1_6_0_, params3x1_.parent_id as parent_i3_6_0_, params3x1_.value as value2_6_0_ from executor executor0_ left outer join paraaaamsssck params3x1_ on executor0_.id=params3x1_.parent_id where executor0_.id=?
Hibernate: select executor0_.id as id1_3_1_, executor0_.parent_id as parent_i2_3_1_, params3x1_.parent_id as parent_i3_6_3_, params3x1_.prop as prop1_6_3_, params3x1_.prop as prop1_6_0_, params3x1_.parent_id as parent_i3_6_0_, params3x1_.value as value2_6_0_ from executor executor0_ left outer join paraaaamsssck params3x1_ on executor0_.id=params3x1_.parent_id where executor0_.id=?
Hibernate: select executor0_.id as id1_3_1_, executor0_.parent_id as parent_i2_3_1_, params3x1_.parent_id as parent_i3_6_3_, params3x1_.prop as prop1_6_3_, params3x1_.prop as prop1_6_0_, params3x1_.parent_id as parent_i3_6_0_, params3x1_.value as value2_6_0_ from executor executor0_ left outer join paraaaamsssck params3x1_ on executor0_.id=params3x1_.parent_id where executor0_.id=?
Hibernate: select executor0_.id as id1_3_1_, executor0_.parent_id as parent_i2_3_1_, params3x1_.parent_id as parent_i3_6_3_, params3x1_.prop as prop1_6_3_, params3x1_.prop as prop1_6_0_, params3x1_.parent_id as parent_i3_6_0_, params3x1_.value as value2_6_0_ from executor executor0_ left outer join paraaaamsssck params3x1_ on executor0_.id=params3x1_.parent_id where executor0_.id=?
Hibernate: select executor0_.id as id1_3_1_, executor0_.parent_id as parent_i2_3_1_, params3x1_.parent_id as parent_i3_6_3_, params3x1_.prop as prop1_6_3_, params3x1_.prop as prop1_6_0_, params3x1_.parent_id as parent_i3_6_0_, params3x1_.value as value2_6_0_ from executor executor0_ left outer join paraaaamsssck params3x1_ on executor0_.id=params3x1_.parent_id where executor0_.id=?
2019-04-19 11:05:19 WARN [localhost-startStop-1] AnnotationConfigServletWebServerApplicationContext.refresh: Exception encountered during context initialization - cancelling refresh attempt: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'fixingTheSessionCrapService': Invocation of init method failed; nested exception is java.lang.StackOverflowError
2019-04-19 11:05:19 INFO [localhost-startStop-1] ExecutorService.killRunningSessions: Killing any running sessions
2019-04-19 11:05:19 INFO [localhost-startStop-1] ExecutorService.killRunningSessions: Done. ATA closed gracefully
2019-04-19 11:05:19 INFO [localhost-startStop-1] ThreadPoolTaskExecutor.shutdown: Shutting down ExecutorService 'getDaemonThreadPool'
2019-04-19 11:05:19 INFO [localhost-startStop-1] LocalContainerEntityManagerFactoryBean.destroy: Closing JPA EntityManagerFactory for persistence unit 'default'
2019-04-19 11:05:19 INFO [localhost-startStop-1] HikariDataSource.close: HikariPool-1 - Shutdown initiated...
2019-04-19 11:05:19 INFO [localhost-startStop-1] HikariDataSource.close: HikariPool-1 - Shutdown completed.
2019-04-19 11:05:19 INFO [localhost-startStop-1] ConditionEvaluationReportLoggingListener.logMessage:
Error starting ApplicationContext. To display the conditions report re-run your application with 'debug' enabled.
2019-04-19 11:05:19 ERROR [localhost-startStop-1] SpringApplication.reportFailure: Application run failed
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'fixingTheSessionCrapService': Invocation of init method failed; nested exception is java.lang.StackOverflowError
at org.springframework.beans.factory.annotation.InitDestroyAnnotationBeanPostProcessor.postProcessBeforeInitialization(InitDestroyAnnotationBeanPostProcessor.java:139)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.applyBeanPostProcessorsBeforeInitialization(AbstractAutowireCapableBeanFactory.java:414)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1770)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:593)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:515)
at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:320)
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222)
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:318)
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:199)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:849)
at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:877)
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:549)
at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:142)
at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:775)
at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:397)
at org.springframework.boot.SpringApplication.run(SpringApplication.java:316)
at org.springframework.boot.web.servlet.support.SpringBootServletInitializer.run(SpringBootServletInitializer.java:157)
at org.springframework.boot.web.servlet.support.SpringBootServletInitializer.createRootApplicationContext(SpringBootServletInitializer.java:137)
at org.springframework.boot.web.servlet.support.SpringBootServletInitializer.onStartup(SpringBootServletInitializer.java:91)
at org.springframework.web.SpringServletContainerInitializer.onStartup(SpringServletContainerInitializer.java:171)
at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5245)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1420)
at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1410)
at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1167)
at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:641)
at java.base/java.lang.Thread.run(Thread.java:844)
Caused by: java.lang.StackOverflowError: null
at java.base/java.nio.charset.CharsetEncoder.encode(CharsetEncoder.java:578)
at java.base/sun.nio.cs.StreamEncoder.implWrite(StreamEncoder.java:292)
at java.base/sun.nio.cs.StreamEncoder.implWrite(StreamEncoder.java:281)
at java.base/sun.nio.cs.StreamEncoder.write(StreamEncoder.java:125)
at java.base/java.io.OutputStreamWriter.write(OutputStreamWriter.java:211)
at java.base/java.io.BufferedWriter.flushBuffer(BufferedWriter.java:120)
at java.base/java.io.PrintStream.write(PrintStream.java:526)
at java.base/java.io.PrintStream.print(PrintStream.java:666)
at java.base/java.io.PrintStream.println(PrintStream.java:803)
at org.apache.tomcat.util.log.SystemLogHandler.println(SystemLogHandler.java:267)
at org.hibernate.engine.jdbc.spi.SqlStatementLogger.logStatement(SqlStatementLogger.java:96)
at org.hibernate.engine.jdbc.spi.SqlStatementLogger.logStatement(SqlStatementLogger.java:78)
at org.hibernate.engine.jdbc.internal.StatementPreparerImpl$StatementPreparationTemplate.prepareStatement(StatementPreparerImpl.java:167)
at org.hibernate.engine.jdbc.internal.StatementPreparerImpl.prepareQueryStatement(StatementPreparerImpl.java:148)
at org.hibernate.loader.Loader.prepareQueryStatement(Loader.java:1984)
at org.hibernate.loader.Loader.executeQueryStatement(Loader.java:1914)
at org.hibernate.loader.Loader.executeQueryStatement(Loader.java:1892)
at org.hibernate.loader.Loader.doQuery(Loader.java:937)
at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:340)
at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:310)
at org.hibernate.loader.Loader.loadEntity(Loader.java:2281)
at org.hibernate.loader.entity.AbstractEntityLoader.load(AbstractEntityLoader.java:64)
at org.hibernate.loader.entity.AbstractEntityLoader.load(AbstractEntityLoader.java:54)
at org.hibernate.persister.entity.AbstractEntityPersister.load(AbstractEntityPersister.java:4271)
at org.hibernate.event.internal.DefaultLoadEventListener.loadFromDatasource(DefaultLoadEventListener.java:511)
at org.hibernate.event.internal.DefaultLoadEventListener.doLoad(DefaultLoadEventListener.java:481)
at org.hibernate.event.internal.DefaultLoadEventListener.load(DefaultLoadEventListener.java:222)
at org.hibernate.event.internal.DefaultLoadEventListener.proxyOrLoad(DefaultLoadEventListener.java:281)
at org.hibernate.event.internal.DefaultLoadEventListener.doOnLoad(DefaultLoadEventListener.java:124)
at org.hibernate.event.internal.DefaultLoadEventListener.onLoad(DefaultLoadEventListener.java:92)
at org.hibernate.internal.SessionImpl.fireLoad(SessionImpl.java:1256)
at org.hibernate.internal.SessionImpl.internalLoad(SessionImpl.java:1139)
at org.hibernate.type.EntityType.resolveIdentifier(EntityType.java:682)
at org.hibernate.type.EntityType.resolve(EntityType.java:464)
at org.hibernate.type.ManyToOneType.resolve(ManyToOneType.java:239)
at org.hibernate.type.EntityType.resolve(EntityType.java:457)
at org.hibernate.type.ComponentType.resolve(ComponentType.java:688)
at org.hibernate.loader.Loader.extractKeysFromResultSet(Loader.java:862)
at org.hibernate.loader.Loader.getRowFromResultSet(Loader.java:718)
at org.hibernate.loader.Loader.processResultSet(Loader.java:990)
at org.hibernate.loader.Loader.doQuery(Loader.java:948)
at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:340)
at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:310)
at org.hibernate.loader.Loader.loadEntity(Loader.java:2281)
at org.hibernate.loader.entity.AbstractEntityLoader.load(AbstractEntityLoader.java:64)
at org.hibernate.loader.entity.AbstractEntityLoader.load(AbstractEntityLoader.java:54)
at org.hibernate.persister.entity.AbstractEntityPersister.load(AbstractEntityPersister.java:4271)
at org.hibernate.event.internal.DefaultLoadEventListener.loadFromDatasource(DefaultLoadEventListener.java:511)
at org.hibernate.event.internal.DefaultLoadEventListener.doLoad(DefaultLoadEventListener.java:481)
at org.hibernate.event.internal.DefaultLoadEventListener.load(DefaultLoadEventListener.java:222)
at org.hibernate.event.internal.DefaultLoadEventListener.proxyOrLoad(DefaultLoadEventListener.java:281)
at org.hibernate.event.internal.DefaultLoadEventListener.doOnLoad(DefaultLoadEventListener.java:124)
at org.hibernate.event.internal.DefaultLoadEventListener.onLoad(DefaultLoadEventListener.java:92)
这是一个长期循环的方式，直到出现StackOverflow异常。最后它说：
at org.hibernate.internal.SessionImpl.fireLoad(SessionImpl.java:1256)
at org.hibernate.internal.SessionImpl.internalLoad(SessionImpl.java:1139)
at org.hibernate.type.EntityType.resolveIdentifier(EntityType.java:682)
at org.hibernate.type.EntityType.resolve(EntityType.java:464)
at org.hibernate.type.ManyToOneType.resolve(ManyToOneType.java:239)
1）让你成为id类Embeddable，因为你有一个ManyToOne关系作为id的一部分：
@Embeddable
class ChildID implements Serializable{
@ManyToOne(cascade = {CascadeType.PERSIST, CascadeType.MERGE})
@JoinColumn(name = "parent_id")
private Parent parent;
private int id;
2）改变Child类：
@Entity
class Child {
@EmbeddedId
private ChildID id;
3）改变父实体上的mappedBy以考虑嵌入关系：
@OneToMany(mappedBy="id.parent")
@Cascasde(value = CascadeType.ALL)
private List<Child> list = ...;
如果有人偶然发现（或者直到会有更好的解决方案），这里实际上对我有用（我为眼睛燃烧类和元素命名道歉，过去几天一直试着这个）。取自@OneToMany and composite primary keys?
@Entity
@Table(name = "paraaaamsssCK")
public class Param1CK {
@EmbeddedId
private Param1CKEmbeddable key;
@Column(name = "value")
private String value;
@MapsId("parentId")
@ManyToOne
@JoinColumn
public Executor parent;
public Param1CK() {
super();
}
public Param1CK(Executor parent, String id, String value) {
key = new Param1CKEmbeddable(id);
this.parent = parent;
this.value = value;
}
}
这是可嵌入的定义：
@Embeddable
public class Param1CKEmbeddable implements Serializable{
private int parentId;
private String id;
public Param1CKEmbeddable（）{}
public Param1CKEmbeddable(int parentId, String id) {
this.parentId = parentId;
this.id = id;
}
public Param1CKEmbeddable(String id) {
this.id = id;
}
@Override
public int hashCode() {
return Objects.hash(parentId, id);
}
}
从“父”，连接很简单：
@OneToMany(mappedBy="parent")
@Cascade(value = CascadeType.ALL)
private List<Param1CK> params3 = new LinkedList<Param1CK>();
希望这有助于下一个将触及这个问题的人。