休眠,JPA - 例子manytomany与两个表
我尝试使用多对多的集合映射,我有两个表: TASK和TASKRELATED,每个任务可以有许多相关的任务,每个相关的任务可以在许多父任务。这里是我的SQL图:休眠,JPA - 例子manytomany与两个表
这里是我的实体:
@Entity
public class Task {
@Id
@GeneratedValue(strategy=GenerationType.IDENTITY)
private Long taskId;
@ManyToMany
@JoinTable(name = "taskRelated", joinColumns = { @JoinColumn(name = "relatedTaskId") }, inverseJoinColumns = { @JoinColumn(name = "taskId") })
private Set<Task> relatedTasks = new HashSet<Task>(0);
}
这里是我的ropository:
public interface ITaskRepository extends JpaRepository<Task, Long>,
QueryDslPredicateExecutor<Task>{
}
这是我的代码:
Task t = repository.findOne(1L);
这是我的数据在MySQL: 任务表
taskrelated表
当我做阅读任务对象的,有恩的错误:
failed to lazily initialize a collection of role: org.Task.relatedTasks, no session or session was closed
org.hibernate.LazyInitializationException: failed to lazily initialize a collection of role: org.Task.relatedTasks, no session or session was closed
at org.hibernate.collection.AbstractPersistentCollection.throwLazyInitializationException(AbstractPersistentCollection.java:383)
at org.hibernate.collection.AbstractPersistentCollection.throwLazyInitializationExceptionIfNotConnected(AbstractPersistentCollection.java:375)
at org.hibernate.collection.AbstractPersistentCollection.readSize(AbstractPersistentCollection.java:122)
at org.hibernate.collection.PersistentSet.size(PersistentSet.java:162)
at com.github.springtestdbunit.sample.service.UsersServiceTest.testTask(UsersServiceTest.java:63)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:601)
at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:44)
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15)
at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:41)
at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:20)
at org.springframework.test.context.junit4.statements.RunBeforeTestMethodCallbacks.evaluate(RunBeforeTestMethodCallbacks.java:74)
at org.springframework.test.context.junit4.statements.RunAfterTestMethodCallbacks.evaluate(RunAfterTestMethodCallbacks.java:83)
at org.springframework.test.context.junit4.statements.SpringRepeat.evaluate(SpringRepeat.java:72)
请帮帮忙!
在@ManyToMany(fetch=FetchType.EAGER)
情况下,有错误是这样的:
illegal access to loading collection
org.hibernate.LazyInitializationException: illegal access to loading collection
at org.hibernate.collection.AbstractPersistentCollection.initialize(AbstractPersistentCollection.java:366)
at org.hibernate.collection.AbstractPersistentCollection.read(AbstractPersistentCollection.java:111)
at org.hibernate.collection.PersistentSet.hashCode(PersistentSet.java:434)
at org.Task.hashCode(Task.java:36)
at java.util.HashMap.hash(HashMap.java:351)
at java.util.HashMap.put(HashMap.java:471)
at java.util.HashSet.add(HashSet.java:217)
at java.util.AbstractCollection.addAll(AbstractCollection.java:334)
at org.hibernate.collection.PersistentSet.endRead(PersistentSet.java:352)
at org.hibernate.engine.loading.CollectionLoadContext.endLoadingCollection(CollectionLoadContext.java:261)
at org.hibernate.engine.loading.CollectionLoadContext.endLoadingCollections(CollectionLoadContext.java:246)
at org.hibernate.engine.loading.CollectionLoadContext.endLoadingCollections(CollectionLoadContext.java:219)
at org.hibernate.loader.Loader.endCollectionLoad(Loader.java:1005)
at org.hibernate.loader.Loader.initializeEntitiesAndCollections(Loader.java:993)
它不能初始化集合,你试图将设定的没有初始化它?:
@ManyToMany
@JoinTable(name = "taskRelated", joinColumns = { @JoinColumn(name = "relatedTaskId") }, inverseJoinColumns = { @JoinColumn(name = "taskId") })
private Set<Task> relatedTasks;
我删除初始化,但同样的错误... – prilia 2014-09-11 12:27:06
由于异常说你正在尝试访问关闭会话后的收集元素 - relatedTasks
,Hibernate默认情况下会延迟加载收集元素。
所以,你需要在会话中访问的元素或者你也可以抓取类型添加到EAGER
@ManyToMany(fetch = FetchType.EAGER)
更新:
按堆栈跟踪异常 - LazyInitializationException: illegal access to loading collection
它具有:
at org.hibernate.collection.PersistentSet.hashCode(PersistentSet.java:434)
at org.nli.seoweb.domain.Task.hashCode(Task.java:36)
基于此,我假设你已经覆盖了hashCode
方法Task
实体,该方法尝试访问Set
。至于Hibernate提供了Set
这是PersistentSet
在这种情况下,包装类,调用hashCode()
内部有一个检查,如果Set
被完全初始化,然后抛出该异常验证。
因此,请尝试修改您的Task.hashCode()
方法,并确保您没有使用其中的Set
,并确定它是否解决了问题。
您也可以参考this post类似的例外。
您忘记发布UsersServiceTest.testTask()。你知道,发生异常的地方。我可以猜测,没有任何JPA事务实际上是在代码周围的任何地方开始的。 – Gimby 2014-09-11 12:46:19