javax.faces.el.E​​valuationException：我的jsf web App中的java.lang.NullPointerException

时间：2013-12-06 23:50:11

标签： jsf-2 nullpointerexception el

我正在开发一个动态Web应用程序，作为第一步，我想使用我的jsf页面在DataBase中保存一个新组。我正在使用Glassfish4连接到Oracle 10g数据库，使用Glassfish4并使用eclipse Kepler primefaces 4.0。这是StackTrace 

                  2013-12-07T00:38:34.028+0100|Avertissement: #{groupeBean.createGroupe}: java.lang.NullPointerException
                 javax.faces.FacesException: #{groupeBean.createGroupe}: java.lang.NullPointerException
at com.sun.faces.application.ActionListenerImpl.processAction(ActionListenerImpl.java:118)
at javax.faces.component.UICommand.broadcast(UICommand.java:315)
at javax.faces.component.UIData.broadcast(UIData.java:1108)
at javax.faces.component.UIViewRoot.broadcastEvents(UIViewRoot.java:790)
at javax.faces.component.UIViewRoot.processApplication(UIViewRoot.java:1282)
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:198)
at javax.faces.webapp.FacesServlet.service(FacesServlet.java:646)
at org.apache.catalina.core.StandardWrapper.service(StandardWrapper.java:1682)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:318)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:160)
at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:734)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:673)
at com.sun.enterprise.web.WebPipeline.invoke(WebPipeline.java:99)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:174)
at org.apache.catalina.connector.CoyoteAdapter.doService(CoyoteAdapter.java:357)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:260)
at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:188)
at org.glassfish.grizzly.http.server.HttpHandler.runService(HttpHandler.java:191)
at org.glassfish.grizzly.http.server.HttpHandler.doHandle(HttpHandler.java:168)
at org.glassfish.grizzly.http.server.HttpServerFilter.handleRead(HttpServerFilter.java:189)
at org.glassfish.grizzly.filterchain.ExecutorResolver$9.execute(ExecutorResolver.java:119)
at org.glassfish.grizzly.filterchain.DefaultFilterChain.executeFilter(DefaultFilterChain.java:288)
at org.glassfish.grizzly.filterchain.DefaultFilterChain.executeChainPart(DefaultFilterChain.java:206)
at org.glassfish.grizzly.filterchain.DefaultFilterChain.execute(DefaultFilterChain.java:136)
at org.glassfish.grizzly.filterchain.DefaultFilterChain.process(DefaultFilterChain.java:114)
at org.glassfish.grizzly.ProcessorExecutor.execute(ProcessorExecutor.java:77)
at org.glassfish.grizzly.nio.transport.TCPNIOTransport.fireIOEvent(TCPNIOTransport.java:838)
at org.glassfish.grizzly.strategies.AbstractIOStrategy.fireIOEvent(AbstractIOStrategy.java:113)
at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy.run0(WorkerThreadIOStrategy.java:115)
at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy.access$100(WorkerThreadIOStrategy.java:55)
at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy$WorkerThreadRunnable.run(WorkerThreadIOStrategy.java:135)
at org.glassfish.grizzly.threadpool.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:564)
at org.glassfish.grizzly.threadpool.AbstractThreadPool$Worker.run(AbstractThreadPool.java:544)
at java.lang.Thread.run(Thread.java:724)
           Caused by: javax.faces.el.EvaluationException: java.lang.NullPointerException
at javax.faces.component.MethodBindingMethodExpressionAdapter.invoke(MethodBindingMethodExpressionAdapter.java:101)
at com.sun.faces.application.ActionListenerImpl.processAction(ActionListenerImpl.java:102)
... 35 more
         Caused by: java.lang.NullPointerException
at com.portail.dao.DaoGroupe.ajouter(DaoGroupe.java:21)
at com.portail.managedBeans.GroupeBean.createGroupe(GroupeBean.java:24)
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:606)
at com.sun.el.parser.AstValue.invoke(AstValue.java:275)
at com.sun.el.MethodExpressionImpl.invoke(MethodExpressionImpl.java:304)
at org.jboss.weld.util.el.ForwardingMethodExpression.invoke(ForwardingMethodExpression.java:40)
at org.jboss.weld.el.WeldMethodExpression.invoke(WeldMethodExpression.java:50)
at com.sun.faces.facelets.el.TagMethodExpression.invoke(TagMethodExpression.java:105)
at javax.faces.component.MethodBindingMethodExpressionAdapter.invoke(MethodBindingMethodExpressionAdapter.java:87)
... 36 more

这是managedBean的代码

                @ManagedBean
                @ViewScoped
              public class GroupeBean {
               private Groupe newGroupe=new Groupe();
                public Groupe getNewGroupe() {
            return newGroupe;
               }
          public void setNewGroupe(Groupe newGroupe) {
      this.newGroupe = newGroupe;
            }
          private DaoGroupe gdao= new DaoGroupe();
        public void createGroupe()
          {
        gdao.ajouter(newGroupe);
            }}

这是Dao Class的代码

            public class DaoGroupe {
private static final String JPA_UNIT_NAME="Portail";
private EntityManager entityManager;
protected EntityManager getEntityManager() {
    if (entityManager == null) {
        entityManager = Persistence.createEntityManagerFactory(
                JPA_UNIT_NAME).createEntityManager();
    }
    return entityManager;
}
 public   void ajouter(Groupe g)
    {
        EntityTransaction tx = entityManager.getTransaction();
        tx.begin();
        entityManager.persist(g);
        tx.commit();}}

这是我的jsf页面中的插入标签

                  <p:tab title="Groupe">
            <h:form>
                <h:panelGrid columns="2">
                    <h:outputText value="Nom : *" />
                    <p:inputText value="#{groupeBean.newGroupe.nom}" required="true"
                        label="nomgrp" validatorMessage="Nom de Groupe Obligatoire" />
                        <h:outputText value="Numéro : *" />
                    <p:inputText value="#{groupeBean.newGroupe.idGroupe}" required="true"
                        label="numgrp" validatorMessage="Numéro de Groupe Obligatoire" />
                </h:panelGrid>
                <p:commandButton value="Ajouter"
                    style="width:205px;margin-left:10%"
                    action="#{groupeBean.createGroupe}" />
            </h:form>

        </p:tab>

1 个答案:

答案 0 :(得分：1)

在方法ajouter中，DaoGroupe-Class中出现NullPointerException。 我想entityManager.getTransaction()是原因，因为entityManager没有填充到任何地方。使用getEntityManager() - 方法替换它可能是开始调试的第一点。

EntityTransaction tx = getEntityManager().getTransaction();

希望它有所帮助...

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