Wie verwenden von JPA 2.0 @ManyToMany ohne Probleme
Ich bin mit JPA 2.0
und Spring
in meiner Entwicklung. Meine entity-Klasse enthält zwei @ManyToMany
Beziehungen.
@Entity("payment")
public class PaymentData implements Serializable
{
private Long pk;
private Collection<PaymentItemData> paymentItem;
/**
* minorPaymentItem
*
*/
private Collection<MinorPayItemData> minorPaymentItem;
@ManyToMany(fetch=FetchType.EAGER)
@JoinTable(name = "payitem_m_assig",
joinColumns =
@JoinColumn(name = "pay_item_id", nullable = false),
inverseJoinColumns =
@JoinColumn(name = "minor_pay_item_id", nullable = false))
public Collection<MinorPayItemData> getMinorPaymentItem()
{
return minorPaymentItem;
}
/**
* @param minorPaymentItem the minorPaymentItem to set
*/
public void setMinorPaymentItem(final Collection<MinorPayItemData> value)
{
this.minorPaymentItem = value;
}
@ManyToMany(fetch=FetchType.EAGER)
@JoinTable(name = "payitem_assigned",
joinColumns =
@JoinColumn(name = "pay_item_id", nullable = false),
inverseJoinColumns =
@JoinColumn(name = "pay_item_id", nullable = false))
public Collection<PaymentItemData> getPaymentItem()
{
return paymentItem;
}
/**
* Set the property paymentItem
*
* @param value -paymentItem
*
*/
public void setPaymentItem(final Collection<PaymentItemData> value)
{
this.paymentItem = value;
}
}
Wenn ich ausführen einer Abfrage zum abrufen von Datensätzen aus der payment Tabelle in der Datenbank, wie
Query q = manager.createQuery("select a from PaymentData a");
q.getResultList();
Wenn ich die fetch=FetchType.EAGER
auf die @ManyToMany
bekomme ich folgende Fehler
Caused by: org.hibernate.loader.MultipleBagFetchException: cannot simultaneously fetch multiple bags
at org.hibernate.loader.BasicLoader.postInstantiate(BasicLoader.java:94)
at org.hibernate.loader.entity.EntityLoader.<init>(EntityLoader.java:119)
at org.hibernate.loader.entity.EntityLoader.<init>(EntityLoader.java:71)
at org.hibernate.loader.entity.EntityLoader.<init>(EntityLoader.java:54)
at org.hibernate.loader.entity.BatchingEntityLoader.createBatchingEntityLoader(BatchingEntityLoader.java:133)
at org.hibernate.persister.entity.AbstractEntityPersister.createEntityLoader(AbstractEntityPersister.java:1914)
at org.hibernate.persister.entity.AbstractEntityPersister.createEntityLoader(AbstractEntityPersister.java:1937)
at org.hibernate.persister.entity.AbstractEntityPersister.createLoaders(AbstractEntityPersister.java:3205)
at org.hibernate.persister.entity.AbstractEntityPersister.postInstantiate(AbstractEntityPersister.java:3191)
at org.hibernate.persister.entity.SingleTableEntityPersister.postInstantiate(SingleTableEntityPersister.java:728)
at org.hibernate.impl.SessionFactoryImpl.<init>(SessionFactoryImpl.java:348)
at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1845)
at org.hibernate.ejb.Ejb3Configuration.buildEntityManagerFactory(Ejb3Configuration.java:906)
... 39 more
Aber wenn ich entfernen fetch=FetchType.EAGER
und lassen Sie es, wie @ManyToMany
habe, werde ich die Ausnahme
org.hibernate.LazyInitializationException: failed to lazily initialize a collection of role: com.data.PaymentData.paymentItem, 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.initialize(AbstractPersistentCollection.java:368)
at org.hibernate.collection.AbstractPersistentCollection.read(AbstractPersistentCollection.java:111)
at org.hibernate.collection.PersistentBag.toString(PersistentBag.java:506)
at java.lang.String.valueOf(String.java:2826)
at java.lang.StringBuilder.append(StringBuilder.java:115)
at com.niu.util.Util.toString(Util.java:131)
at com.niu.util.data.BaseData.toString(BaseData.java:107)
at java.lang.String.valueOf(String.java:2826)
at java.lang.StringBuilder.append(StringBuilder.java:115)
at java.util.AbstractCollection.toString(AbstractCollection.java:422)
at java.lang.String.valueOf(String.java:2826)
at java.io.PrintStream.println(PrintStream.java:771)
at org.apache.tomcat.util.log.SystemLogHandler.println(SystemLogHandler.java:269)
at sun.reflect.GeneratedMethodAccessor1861.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at com.opensymphony.xwork2.DefaultActionInvocation.invokeAction(DefaultActionInvocation.java:452)
at com.opensymphony.xwork2.DefaultActionInvocation.invokeActionOnly(DefaultActionInvocation.java:291)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:254)
at com.opensymphony.xwork2.interceptor.DefaultWorkflowInterceptor.doIntercept(DefaultWorkflowInterceptor.java:176)
at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248)
at com.opensymphony.xwork2.interceptor.ConversionErrorInterceptor.intercept(ConversionErrorInterceptor.java:133)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248)
at com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java:207)
at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248)
at com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java:207)
at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248)
at com.opensymphony.xwork2.interceptor.StaticParametersInterceptor.intercept(StaticParametersInterceptor.java:190)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248)
at org.apache.struts2.interceptor.MultiselectInterceptor.intercept(MultiselectInterceptor.java:75)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248)
at org.apache.struts2.interceptor.CheckboxInterceptor.intercept(CheckboxInterceptor.java:94)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248)
at com.niu.web.common.interceptor.ApplicationModelDrivenInterceptor.intercept(ApplicationModelDrivenInterceptor.java:31)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248)
at com.opensymphony.xwork2.interceptor.ScopedModelDrivenInterceptor.intercept(ScopedModelDrivenInterceptor.java:141)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248)
at org.apache.struts2.interceptor.ProfilingActivationInterceptor.intercept(ProfilingActivationInterceptor.java:104)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248)
at org.apache.struts2.interceptor.debugging.DebuggingInterceptor.intercept(DebuggingInterceptor.java:270)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248)
at com.opensymphony.xwork2.interceptor.ChainingInterceptor.intercept(ChainingInterceptor.java:145)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248)
at com.opensymphony.xwork2.interceptor.PrepareInterceptor.doIntercept(PrepareInterceptor.java:171)
at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248)
at com.opensymphony.xwork2.interceptor.I18nInterceptor.intercept(I18nInterceptor.java:176)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248)
at org.apache.struts2.interceptor.ServletConfigInterceptor.intercept(ServletConfigInterceptor.java:164)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248)
at com.opensymphony.xwork2.interceptor.AliasInterceptor.intercept(AliasInterceptor.java:190)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248)
at com.opensymphony.xwork2.interceptor.ExceptionMappingInterceptor.intercept(ExceptionMappingInterceptor.java:187)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248)
at org.apache.struts2.impl.StrutsActionProxy.execute(StrutsActionProxy.java:52)
at org.apache.struts2.dispatcher.Dispatcher.serviceAction(Dispatcher.java:498)
at org.apache.struts2.dispatcher.ng.ExecuteOperations.executeAction(ExecuteOperations.java:77)
at org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter.doFilter(StrutsPrepareAndExecuteFilter.java:91)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:240)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:164)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:462)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:164)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:100)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:563)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:399)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:317)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:204)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:311)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
at java.lang.Thread.run(Thread.java:662)
Was mache ich falsch
Du musst angemeldet sein, um einen Kommentar abzugeben.
Zu vermeiden, die
MultipleBagFetchException
anstelle vonFetchType.EAGER
, versuchen Sie es mit der@LazyCollection(LazyCollectionOption.FALSE)
wie in diesem Beispiel:Hier ist eine kleine Beschreibung von der docs:
Ich hoffe, es hilft
Der beste Weg ist, um die XxxtoMany Verbände faul (der Standard). Auf diese Weise werden die Kollektionen werden nur geladen, wenn Sie benötigt werden, oder wenn Sie sagen, Hibernate zu Holen, Sie eifrig mit einer Abfrage mit einer join-fetch-Klausel. Machen Sie bereit, die Kräfte Ruhezustand zu immer laden Sie, auch wenn Sie diese nicht benötigen.
Natürlich, wenn Sie Sie brauchen und Sie sind so konfiguriert, wie FAUL, Sie können nur geladen werden, wenn die Sitzung noch offen ist. Sobald die Sitzung wird geschlossen, das Unternehmen wird abgetrennt, und die Sammlungen können nicht faul sein-mehr geladen. Sie müssen daher initialisieren Sie Sie explizit (durch den Aufruf einer Methode der Sammlung, oder durch aufrufen
Hibernate.initialize(collection)
) vor der Schließung der Sitzung.Wenn Sie wirklich wollen, halten Sie diese Spannung geladen, dann sollte nur eines von beiden sein, eine Tasche (also der Typ
Collection
oderList
). Die anderen sollte erklärt werden, wieSet
.Seite Hinweis: die Zuordnung der die zweite Assoziation ist falsch: bist du mit dem gleichen join-Spalte zweimal.