0 Replies Latest reply on Aug 5, 2012 11:17 AM by margul

    EntityManagerFactory.createEntityManagerFactory(String) throws strange NullPointerException

    margul Newbie

      Hi everybody,

       

      I ran into a problem, for which I couldn't find a solution th whole day.

       

      I'm developing a 3-tier application for JBoss 7.1.1, and from the logic tier, I want to call a stateless session bean, which accesses my MySQL DB via JPA and Hibernate.

       

      A logic bean calls the dao bean via JNDI, which works perfectly:

      {code}

      package logic;

       

      import dao.vehicle.VehicleDAOLocal;

      import dao.vehicle.VehicleDAO;

       

      import javax.ejb.LocalBean;

      import javax.ejb.Stateless;

      import javax.naming.Context;

      import javax.naming.InitialContext;

      import javax.naming.NamingException;

       

      @Stateless

      @LocalBean

      public class VehicleLogic implements VehicleLogicRemote{

      /**

      * Default constructor.

      */

      public VehicleLogic() {

      // TODO Auto-generated constructor stub

      }

       

       

       

      @Override

      public List<Vehicle> getVehicles(){

       

       

                Context context = null;

           VehicleDAOLocal dao = null;

                try {

                          context = new InitialContext();

       

                          dao = (VehicleDAO)context.lookup("java:app/de.zielpuls.rent20.datamodel/VehicleDAO!de.zielpuls.rent20.server.dao.vehicle.VehicleDAO");

                } catch (NamingException e) {

                          // TODO Auto-generated catch block

                          e.printStackTrace();

                }

                return dao.getVehicles();

      }

      {code}

       

      In the constructor of the DAO class, I want to instantiate my EntityManager.

      Injection via @PersistenceContext also didn't work, the EntityManager was always null,but I think, this is the same problem.

       

      {code}

      package dao.vehicle;

       

       

      import javax.ejb.LocalBean;

      import javax.ejb.Stateless;

      import javax.persistence.EntityManager;

      import javax.persistence.EntityManagerFactory;

       

       

       

      /**

      * Session Bean implementation class VehicleDAO

      */

      @Stateless

      @LocalBean

      public class VehicleDAO implements VehicleDAOLocal {

       

                EntityManager em;

                private EntityManagerFactory factory;

                public VehicleDAO(){

       

                          factory = Persistence.createEntityManagerFactory("vehicle");

                          em = factory.createEntityManager();

       

                }

      }


      {code}

      In the constructor, the first line

       

      factory = Persistence.createEntityManagerFactory("vehicle");

       

      works (because I set <property name="hibernate.hbm2ddl.auto" value="create-drop" /> in the persistence.xml, even the tables are created, so this can't be a problem finding the MySQL driver), but in the second line

       

      em = factory.createEntityManager();

       

      I get at this stacktrace

       


      {code}

       




      ViewManagedReferenceFactory.getReference() line: 52

      WritableServiceBasedNamingStore(ServiceBasedNamingStore).lookup(String, ServiceName) line: 133

      WritableServiceBasedNamingStore(ServiceBasedNamingStore).lookup(Name) line: 74

      NamingContext.lookup(Name) line: 178

      InitialContext.lookup(Name) line: 123

      InitialContext(NamingContext).lookup(String) line: 214

      InitialContext.lookup(String) line: not available

      VehicleLogic.getVehicles() line: 58

      NativeMethodAccessorImpl.invoke0(Method, Object, Object[]) line: not available [native method]

      NativeMethodAccessorImpl.invoke(Object, Object[]) line: not available

      DelegatingMethodAccessorImpl.invoke(Object, Object[]) line: not available

      Method.invoke(Object, Object...) line: not available

      ManagedReferenceMethodInterceptorFactory$ManagedReferenceMethodInterceptor.processInvocation(InterceptorContext) line: 72

      InterceptorContext.proceed() line: 288

      WeavedInterceptor.processInvocation(InterceptorContext) line: 53

      UserInterceptorFactory$1.processInvocation(InterceptorContext) line: 36

      InterceptorContext.proceed() line: 288

      SBInvocationInterceptor.processInvocation(InterceptorContext) line: 47

      InterceptorContext.proceed() line: 288

      InitialInterceptor.processInvocation(InterceptorContext) line: 21

      InterceptorContext.proceed() line: 288

      ChainedInterceptor.processInvocation(InterceptorContext) line: 61

      ComponentDispatcherInterceptor.processInvocation(InterceptorContext) line: 53

      InterceptorContext.proceed() line: 288

      PooledInstanceInterceptor.processInvocation(InterceptorContext) line: 51

      InterceptorContext.proceed() line: 288

      CMTTxInterceptor.invokeInOurTx(InterceptorContext, TransactionManager, EJBComponent) line: 228

      CMTTxInterceptor.required(InterceptorContext, EJBComponent, int) line: 304

      CMTTxInterceptor.processInvocation(InterceptorContext) line: 190

      InterceptorContext.proceed() line: 288

      CurrentInvocationContextInterceptor.processInvocation(InterceptorContext) line: 41

      InterceptorContext.proceed() line: 288

      LoggingInterceptor.processInvocation(InterceptorContext) line: 59

      InterceptorContext.proceed() line: 288

      NamespaceContextInterceptor.processInvocation(InterceptorContext) line: 50

      InterceptorContext.proceed() line: 288

      AdditionalSetupInterceptor.processInvocation(InterceptorContext) line: 32

      InterceptorContext.proceed() line: 288

      TCCLInterceptor.processInvocation(InterceptorContext) line: 45

      InterceptorContext.proceed() line: 288

      ChainedInterceptor.processInvocation(InterceptorContext) line: 61

      ViewService$View.invoke(InterceptorContext) line: 165

      ViewDescription$1.processInvocation(InterceptorContext) line: 173

      InterceptorContext.proceed() line: 288

      ChainedInterceptor.processInvocation(InterceptorContext) line: 61

      ProxyInvocationHandler.invoke(Object, Method, Object[]) line: 72

      VehicleLogic$$$view4.getVehicles() line: not available

      VehicleService.getVehicles() line: 64

      NativeMethodAccessorImpl.invoke0(Method, Object, Object[]) line: not available [native method]

      NativeMethodAccessorImpl.invoke(Object, Object[]) line: not available

      DelegatingMethodAccessorImpl.invoke(Object, Object[]) line: not available

      Method.invoke(Object, Object...) line: not available

      MethodInjectorImpl.invoke(HttpRequest, HttpResponse, Object) line: 155

      ResourceMethod.invokeOnTarget(HttpRequest, HttpResponse, Object) line: 257

      ResourceMethod.invoke(HttpRequest, HttpResponse, Object) line: 222

      ResourceLocator.invokeOnTargetObject(HttpRequest, HttpResponse, Object) line: 152

      ResourceLocator.invoke(HttpRequest, HttpResponse) line: 91

      SynchronousDispatcher.getResponse(HttpRequest, HttpResponse, ResourceInvoker) line: 525

      SynchronousDispatcher.invoke(HttpRequest, HttpResponse, ResourceInvoker) line: 502

      SynchronousDispatcher.invoke(HttpRequest, HttpResponse) line: 119

      ServletContainerDispatcher.service(String, HttpServletRequest, HttpServletResponse, boolean) line: 208

      HttpServletDispatcher.service(String, HttpServletRequest, HttpServletResponse) line: 55

      HttpServletDispatcher.service(HttpServletRequest, HttpServletResponse) line: 50

      HttpServletDispatcher(HttpServlet).service(ServletRequest, ServletResponse) line: 847

      ApplicationFilterChain.internalDoFilter(ServletRequest, ServletResponse) line: 329

      ApplicationFilterChain.doFilter(ServletRequest, ServletResponse) line: 248

      StandardWrapperValve.invoke(Request, Response) line: 275

      StandardContextValve.invoke(Request, Response) line: 161

      WebNonTxEmCloserValve.invoke(Request, Response) line: 50

      SecurityContextAssociationValve.invoke(Request, Response) line: 153

      StandardHostValve.invoke(Request, Response) line: 155

      ErrorReportValve.invoke(Request, Response) line: 102

      StandardEngineValve.invoke(Request, Response) line: 109

      CoyoteAdapter.service(Request, Response) line: 368

      Http11Processor.process(Socket) line: 877

      Http11Protocol$Http11ConnectionHandler.process(Socket) line: 671

      JIoEndpoint$Worker.run() line: 930

      Thread.run() line: not available {code}

       

       

       

      a NullPointerException (in ViewManagedReferenceFactory.getReference() line: 52) with detail message null and as cause only again a NullPointerException and there in again and again.

      (The line were I call is the createEntityManager() method is "VehicleLogic.getVehicles() line: 58")

      I also can see the exception only during debugging in the variables-view of Eclipse, nothing gets out to the console.

       

      My persistence.xml looks like

      {code:xml}

      <?xml version="1.0" encoding="UTF-8"?>

      <persistence version="2.0" xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd">

                <persistence-unit name="vehicle" transaction-type="JTA">

                <!-- <provider>org.hibernate.ejb.HibernatePersistence</provider>-->

                 <jta-data-source>java:/MySqlDS</jta-data-source>

                          <class>de.zielpuls.rent20.server.datamodel.vehicle.Vehicle</class>

                          <properties>

                                 <property name="hibernate.hbm2ddl.auto" value="create-drop" />

                              <property name="hibernate.show_sql" value="true" />

                                 <property name="hibernate.dialect" value="org.hibernate.dialect.MySQLDialect" />

                        </properties>

                </persistence-unit>

      </persistence>

       

      {code:xml}

       

      and I added the driver via datasource as a modul:

       

       

      {code:xml}

      <datasource jta="false" jndi-name="java:/MySqlDS" pool-name="MySqlDS_Pool" enabled="true" use-ccm="false">

                          <connection-url>jdbc:mysql://localhost:3306/vehicle</connection-url>

                          <driver>com.mysql</driver>

                          <security>

                              <user-name>root</user-name>

                              <password>mysql</password>

                          </security>

                      </datasource>

                      <drivers>

                          <driver name="com.mysql" module="com.mysql">

                              <xa-datasource-class>com.mysql.jdbc.jdbc2.optional.MysqlXADataSource</xa-datasource-class>

                          </driver>

                      </drivers>

      </datasources>

      {code:xml}

       

      But as I said, tables are created, so I think it isn't a problem of the DB driver, and I also got the same exception with H2 database.

       

      Now I don't know further anymore...

       

      Maybe somebody has an idea?

       

      Thank you and best regards

      Markus