Question

使用Spring MVC，Hibernate和JPA。我试图从Controller加载一些Collection并运行到LazyLoading Exception。所以我想切换到Egar加载。

我有两个班级（Flightroute和Measurstations，它们处于多对多的现实中）

@Entity
@Table(name = "flightroutes")
public class Flightroute extends DomainObject<Integer> {

    @ManyToMany(fetch=FetchType.EAGER)
    private List<MeasureStation> measureStation;

@Entity
@Table(name = "measurestations")
public class MeasureStation extends DomainObject<Long> {
    @ManyToMany(mappedBy = "measureStation")
    private List<Flightroute> flightroutes;

但这似乎不起作用，当应用程序启动时遇到以下异常

Mai 03,2013 5:58:08 PM org.apache.catalina.core.StandardContext listenerStart SEVERE：将上下文初始化事件发送到类org.springframework.web.context.ContextLoaderListener的侦听器实例的异常 org.springframework.beans.factory.BeanCreationException：使用名称＆＃39; entityManagerFactory＆＃39;创建bean时出错。在ServletContext资源[/WEB-INF/applicationContext.xml]中定义：init方法的调用失败;嵌套异常是javax.persistence.PersistenceException：[PersistenceUnit：atm]无法构建EntityManagerFactory 在org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean（AbstractAutowireCapableBeanFactory.java:1488）在org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean（AbstractAutowireCapableBeanFactory.java:524）在org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean（AbstractAutowireCapableBeanFactory.java:461） at org.springframework.beans.factory.support.AbstractBeanFactory $ 1.getObject（AbstractBeanFactory.java:295）在org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton（DefaultSingletonBeanRegistry.java:223）在org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean（AbstractBeanFactory.java:292）在org.springframework.beans.factory.support.AbstractBeanFactory.getBean（AbstractBeanFactory.java:194）在org.springframework.context.support.AbstractApplicationContext.getBean（AbstractApplicationContext.java:1117）在org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization（AbstractApplicationContext.java:922）在org.springframework.context.support.AbstractApplicationContext.refresh（AbstractApplicationContext.java:479） at org.springframework.web.context.ContextLoader.configureAndRefreshWebApplicationContext（ContextLoader.java:389）在org.springframework.web.context.ContextLoader.initWebApplicationContext（ContextLoader.java:294）在org.springframework.web.context.ContextLoaderListener.contextInitialized（ContextLoaderListener.java:112）在org.apache.catalina.core.StandardContext.listenerStart（StandardContext.java:4791） at org.apache.catalina.core.StandardContext.startInternal（StandardContext.java:5285）在org.apache.catalina.util.LifecycleBase.start（LifecycleBase.java:150）在org.apache.catalina.core.ContainerBase $ StartChild.call（ContainerBase.java:1559）在org.apache.catalina.core.ContainerBase $ StartChild.call（ContainerBase.java:1549） at java.util.concurrent.FutureTask $ Sync.innerRun（Unknown Source） at java.util.concurrent.FutureTask.run（Unknown Source） at java.util.concurrent.ThreadPoolExecutor.runWorker（Unknown Source） at java.util.concurrent.ThreadPoolExecutor $ Worker.run（Unknown Source）在java.lang.Thread.run（未知来源）引起：javax.persistence.PersistenceException：[PersistenceUnit：atm]无法构建EntityManagerFactory 在org.hibernate.ejb.Ejb3Configuration.buildEntityManagerFactory（Ejb3Configuration.java:930）在org.hibernate.ejb.Ejb3Configuration.buildEntityManagerFactory（Ejb3Configuration.java:904）在org.hibernate.ejb.HibernatePersistence.createContainerEntityManagerFactory（HibernatePersistence.java:92）在org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean.createNativeEntityManagerFactory（LocalContainerEntityManagerFactoryBean.java:288）在org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.afterPropertiesSet（AbstractEntityManagerFactoryBean.java:310）在org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods（AbstractAutowireCapableBeanFactory.java:1547）在org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean（AbstractAutowireCapableBeanFactory.java:1485） ......还有22个引起：org.hibernate.loader.MultipleBagFetchException：无法同时获取多个包在org.hibernate.loader.BasicLoader.postInstantiate（BasicLoader.java:93）在org.hibernate.loader.entity.EntityLoader。（EntityLoader.java:118）在org.hibernate.loader.entity.EntityLoader。（EntityLoader.java:70）在org.hibernate.loader.entity.EntityLoader。（EntityLoader.java:53）在org.hibernate.loader.entity.BatchingEntityLoaderBuilder.buildLoader（BatchingEntityLoaderBuilder.java:75）在org.hibernate.persister.entity.AbstractEntityPersister.createEntityLoader（AbstractEntityPersister.java:2483）在org.hibernate.persister.entity.AbstractEntityPersister.createEntityLoader（AbstractEntityPersister.java:2496）在org.hibernate.persister.entity.AbstractEntityPersister.createLoaders（AbstractEntityPersister.java:3832）在org.hibernate.persister.entity.AbstractEntityPersister.postInstantiate（AbstractEntityPersister.java:3818）在org.hibernate.persister.entity.SingleTableEntityPersister.postInstantiate（SingleTableEntityPersister.java:1018）在org.hibernate.internal.SessionFactoryImpl。（SessionFactoryImpl.java:461）在org.hibernate.cfg.Configuration.buildSessionFactory（Configuration.java:1750）在org.hibernate.ejb.EntityManagerFactoryImpl。（EntityManagerFactoryImpl.java:94）在org.hibernate.ejb.Ejb3Configuration.buildEntityManagerFactory（Ejb3Configuration.java:920） ......还有28个

我没有得到它，任何人都可以帮助我，和/或解释为什么会发生这种情况？

Answer 1

发现：

 @ManyToMany(fetch=FetchType.EAGER)
    private List<MeasureStation> measureStation;

如果有两个列表，hibernate想要保持列表中元素的排序（带连接等），hibernate不能保持顺序。

拥有look

Hibernate / JPA无法进行急切加载

1 个答案: