使用hibernate @LazyCollection（LazyCollectionOption.FALSE）注释时无法仅删除子对象

Question

我已阅读there并且我使用@LazyCollection（LazyCollectionOption.FALSE）出于类似的原因在我的Entity类中： EntityCity.java：

@ManyToOne
@JoinColumn(name="Country_Id")
private EntityCountry mcountry;

public EntityCountry getMcountry() { return mcountry; }
public void setMcountry(EntityCountry mcountry) { this.mcountry = mcountry; }

EntityCountry.java：

@LazyCollection(LazyCollectionOption.FALSE)
@OneToMany(mappedBy="mcountry", targetEntity= EntityCity.class, cascade= CascadeType.ALL)
private List<EntityCity> cities;

public List<EntityCity> getCities() { return cities; }
public void setCities(List<EntityCity> cities) { this.cities = cities; }

但是当我尝试删除一个子对象时，它会抛出此异常：

WARNING: #{city.delete()}: java.lang.IllegalStateException: Transaction not active
javax.faces.FacesException: #{city.delete()}: java.lang.IllegalStateException: Transaction not active
    at com.sun.faces.application.ActionListenerImpl.processAction(ActionListenerImpl.java:118)
    at javax.faces.component.UICommand.broadcast(UICommand.java:315)
    at javax.faces.component.UIViewRoot.broadcastEvents(UIViewRoot.java:794)
    at javax.faces.component.UIViewRoot.processApplication(UIViewRoot.java:1259)
    at com.sun.faces.lifecycle.InvokeApplicationPhase.execute(InvokeApplicationPhase.java:81)
    at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101)
    at com.sun.faces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:118)
    at javax.faces.webapp.FacesServlet.service(FacesServlet.java:593)
    at org.apache.catalina.core.StandardWrapper.service(StandardWrapper.java:1539)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:281)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175)
    at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:655)
    at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:595)
    at com.sun.enterprise.web.WebPipeline.invoke(WebPipeline.java:98)
    at com.sun.enterprise.web.PESessionLockingStandardPipeline.invoke(PESessionLockingStandardPipeline.java:91)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:162)
    at org.apache.catalina.connector.CoyoteAdapter.doService(CoyoteAdapter.java:330)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:231)
    at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:174)
    at com.sun.grizzly.http.ProcessorTask.invokeAdapter(ProcessorTask.java:828)
    at com.sun.grizzly.http.ProcessorTask.doProcess(ProcessorTask.java:725)
    at com.sun.grizzly.http.ProcessorTask.process(ProcessorTask.java:1019)
    at com.sun.grizzly.http.DefaultProtocolFilter.execute(DefaultProtocolFilter.java:225)
    at com.sun.grizzly.DefaultProtocolChain.executeProtocolFilter(DefaultProtocolChain.java:137)
    at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:104)
    at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:90)
    at com.sun.grizzly.http.HttpProtocolChain.execute(HttpProtocolChain.java:79)
    at com.sun.grizzly.ProtocolChainContextTask.doCall(ProtocolChainContextTask.java:54)
    at com.sun.grizzly.SelectionKeyContextTask.call(SelectionKeyContextTask.java:59)
    at com.sun.grizzly.ContextTask.run(ContextTask.java:71)
    at com.sun.grizzly.util.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:532)
    at com.sun.grizzly.util.AbstractThreadPool$Worker.run(AbstractThreadPool.java:513)
    at java.lang.Thread.run(Thread.java:722)
Caused by: javax.faces.el.EvaluationException: java.lang.IllegalStateException: Transaction not active
    at javax.faces.component.MethodBindingMethodExpressionAdapter.invoke(MethodBindingMethodExpressionAdapter.java:102)
    at com.sun.faces.application.ActionListenerImpl.processAction(ActionListenerImpl.java:102)
    ... 32 more
Caused by: java.lang.IllegalStateException: Transaction not active
    at org.hibernate.ejb.TransactionImpl.rollback(TransactionImpl.java:104)
    at test.CityBean.delete(CityBean.java:42)
    at test.org$jboss$weld$bean-web-ManagedBean-class_test$CityBean_$$_WeldClientProxy.delete(org$jboss$weld$bean-web-ManagedBean-class_test$CityBean_$$_WeldClientProxy.java)
    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 javax.el.BeanELResolver.invokeMethod(BeanELResolver.java:737)
    at javax.el.BeanELResolver.invoke(BeanELResolver.java:467)
    at javax.el.CompositeELResolver.invoke(CompositeELResolver.java:254)
    at com.sun.el.parser.AstValue.invoke(AstValue.java:228)
    at com.sun.el.MethodExpressionImpl.invoke(MethodExpressionImpl.java:297)
    at org.jboss.weld.util.el.ForwardingMethodExpression.invoke(ForwardingMethodExpression.java:43)
    at org.jboss.weld.el.WeldMethodExpression.invoke(WeldMethodExpression.java:56)
    at com.sun.faces.facelets.el.TagMethodExpression.invoke(TagMethodExpression.java:105)
    at javax.faces.component.MethodBindingMethodExpressionAdapter.invoke(MethodBindingMethodExpressionAdapter.java:88)
    ... 33 more

并删除代码：

public void delete() {
        EntityManager em = emf.createEntityManager();
        try {
            EntityTransaction entr = em.getTransaction();
            boolean committed = false;
            entr.begin();
            try {
                EntityCity city = em.find(EntityCity.class, 7);
                em.remove(city);
                entr.commit();
                committed = true;
            } finally {
                if(!committed) entr.rollback();
            }
        } finally {
            em.close();
        }

当我不使用“@LazyCollection（LazyCollectionOption.FALSE）”代码运行良好但我需要它。什么是最好的解决方案？