我正在使用this教程来学习JavaEE Web应用程序。我在Windows XP上使用eclipse indigo，在windows xp上使用objectdb-2.4.2_02，glassfish 3.1.2。当我运行该程序时，嵌入式浏览器打开具有此状态的页面。打印javax.ejb.EJBException。我谷歌它，但我没有找到这个问题的答案。
HTTP Status 500 -
--------------------------------------------------------------------------------
type Exception report
message
descriptionThe server encountered an internal error () that prevented it from fulfilling this request.
exception
javax.ejb.EJBException
note The full stack traces of the exception and its root causes are available in the GlassFish Server Open Source Edition 3.1.2.2 logs.
--------------------------------------------------------------------------------
GlassFish Server Open Source Edition 3.1.2.2
服务器日志文件：
[#|2012-08-23T15:51:38.979+0300|WARNING|glassfish3.1.2|javax.enterprise.system.container.web.com.sun.enterprise.web|_ThreadID=21;_ThreadName=Thread-2;|StandardWrapperValve[GuestServlet]: PWC1406: Servlet.service() for servlet GuestServlet threw exception
javax.ejb.EJBException
at com.sun.ejb.containers.BaseContainer.processSystemException(BaseContainer.java:5215)
at com.sun.ejb.containers.BaseContainer.completeNewTx(BaseContainer.java:5113)
at com.sun.ejb.containers.BaseContainer.postInvokeTx(BaseContainer.java:4901)
at com.sun.ejb.containers.BaseContainer.postInvoke(BaseContainer.java:2045)
at com.sun.ejb.containers.BaseContainer.postInvoke(BaseContainer.java:1994)
at com.sun.ejb.containers.EJBLocalObjectInvocationHandler.invoke(EJBLocalObjectInvocationHandler.java:222)
at com.sun.ejb.containers.EJBLocalObjectInvocationHandlerDelegate.invoke(EJBLocalObjectInvocationHandlerDelegate.java:89)
at $Proxy130.getAllGuests(Unknown Source)
at guest.__EJB31_Generated__GuestDao__Intf____Bean__.getAllGuests(Unknown Source)
at guest.GuestServlet.doGet(GuestServlet.java:24)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:668)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:770)
at org.apache.catalina.core.StandardWrapper.service(StandardWrapper.java:1550)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:281)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175)
at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:655)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:595)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:161)
at org.apache.catalina.connector.CoyoteAdapter.doService(CoyoteAdapter.java:331)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:231)
at com.sun.enterprise.v3.services.impl.ContainerMapper$AdapterCallable.call(ContainerMapper.java:317)
at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:195)
at com.sun.grizzly.http.ProcessorTask.invokeAdapter(ProcessorTask.java:860)
at com.sun.grizzly.http.ProcessorTask.doProcess(ProcessorTask.java:757)
at com.sun.grizzly.http.ProcessorTask.process(ProcessorTask.java:1056)
at com.sun.grizzly.http.DefaultProtocolFilter.execute(DefaultProtocolFilter.java:229)
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: java.lang.IllegalStateException: Unable to retrieve EntityManagerFactory for unitName GuestbookPU
at com.sun.enterprise.container.common.impl.EntityManagerWrapper.init(EntityManagerWrapper.java:132)
at com.sun.enterprise.container.common.impl.EntityManagerWrapper._getDelegate(EntityManagerWrapper.java:173)
at com.sun.enterprise.container.common.impl.EntityManagerWrapper.createQuery(EntityManagerWrapper.java:467)
at guest.GuestDao.getAllGuests(GuestDao.java:22)
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.glassfish.ejb.security.application.EJBSecurityManager.runMethod(EJBSecurityManager.java:1052)
at org.glassfish.ejb.security.application.EJBSecurityManager.invoke(EJBSecurityManager.java:1124)
at com.sun.ejb.containers.BaseContainer.invokeBeanMethod(BaseContainer.java:5388)
at com.sun.ejb.EjbInvocation.invokeBeanMethod(EjbInvocation.java:619)
at com.sun.ejb.containers.interceptors.AroundInvokeChainImpl.invokeNext(InterceptorManager.java:800)
at com.sun.ejb.EjbInvocation.proceed(EjbInvocation.java:571)
at com.sun.ejb.containers.interceptors.SystemInterceptorProxy.doAround(SystemInterceptorProxy.java:162)
at com.sun.ejb.containers.interceptors.SystemInterceptorProxy.aroundInvoke(SystemInterceptorProxy.java:144)
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 com.sun.ejb.containers.interceptors.AroundInvokeInterceptor.intercept(InterceptorManager.java:861)
at com.sun.ejb.containers.interceptors.AroundInvokeChainImpl.invokeNext(InterceptorManager.java:800)
at com.sun.ejb.containers.interceptors.InterceptorManager.intercept(InterceptorManager.java:370)
at com.sun.ejb.containers.BaseContainer.__intercept(BaseContainer.java:5360)
at com.sun.ejb.containers.BaseContainer.intercept(BaseContainer.java:5348)
at com.sun.ejb.containers.EJBLocalObjectInvocationHandler.invoke(EJBLocalObjectInvocationHandler.java:214)
... 30 more
|#]
答案 0 :(得分：0)
只有部分答案......
关键问题是
Caused by: java.lang.IllegalStateException:
Unable to retrieve EntityManagerFactory for unitName null
这意味着它无法确定它应该在GuestDAO中使用哪个PersistenceUnit。这可能表明GF无法在项目中找到您的persistence.xml文件，请仔细检查the creation of persistence.xml as described是否顺利进行以及是否在部署的项目中是否存在persistence.xml和ONCE ONCE（曾经的部分是因为我已经注意到Eclipselink在一个项目中遇到多个persistence.xml文件时会感到很困惑。如果一切正常，请将单位的名称添加到GuestsDAO中的@PersistenceContext注释中，如下所示
@PersistenceContext(unitName="GuestbookPU")
private EntityManager em;
如果所有这些都失败了，请告诉我。
答案 1 :(得分：0)
根据我的经验，它是某种数据库连接问题。最好的办法是登录服务器并PING数据库以查看它是否有效。