K19 - Ajuda com JSF e integração JPA

Olá, estou seguindo um tutorial da apostila da K19 e estou afzendo a parte Integração JSF e JPA, pois bem esbarrei no seguinte problema.

Quando executo a pagina carros.xhtml acontece o seguinte:

Stack trace

SEVERE: Error Rendering View[/carros.xhtml]
[b]javax.el.ELException: /carros.xhtml @26,57 rendered="#{not empty carroBean.carros}": java.lang.NullPointerException[/b]
	at com.sun.faces.facelets.el.TagValueExpression.getValue(TagValueExpression.java:114)
	at javax.faces.component.ComponentStateHelper.eval(ComponentStateHelper.java:194)
	at javax.faces.component.UIComponentBase.isRendered(UIComponentBase.java:462)
	at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1850)
	at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1859)
	at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1859)
	at com.sun.faces.application.view.FaceletViewHandlingStrategy.renderView(FaceletViewHandlingStrategy.java:443)
	at com.sun.faces.application.view.MultiViewHandler.renderView(MultiViewHandler.java:131)
	at com.sun.faces.lifecycle.RenderResponsePhase.execute(RenderResponsePhase.java:120)
	at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101)
	at com.sun.faces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:219)
	at javax.faces.webapp.FacesServlet.service(FacesServlet.java:647)
	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.el.ELException: java.lang.NullPointerException
	at javax.el.BeanELResolver.getValue(BeanELResolver.java:368)
	at com.sun.faces.el.DemuxCompositeELResolver._getValue(DemuxCompositeELResolver.java:176)
	at com.sun.faces.el.DemuxCompositeELResolver.getValue(DemuxCompositeELResolver.java:203)
	at com.sun.el.parser.AstValue.getValue(AstValue.java:140)
	at com.sun.el.parser.AstValue.getValue(AstValue.java:204)
	at com.sun.el.parser.AstEmpty.getValue(AstEmpty.java:66)
	at com.sun.el.parser.AstNot.getValue(AstNot.java:63)
	at com.sun.el.ValueExpressionImpl.getValue(ValueExpressionImpl.java:226)
	at com.sun.faces.facelets.el.TagValueExpression.getValue(TagValueExpression.java:109)
	... 38 more
Caused by: java.lang.NullPointerException
	at br.com.k19.modelo.CarroRepository.buscaTodos(CarroRepository.java:20)
	at br.com.k19.controle.CarroBean.getCarros(CarroBean.java:36)
	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 javax.el.BeanELResolver.getValue(BeanELResolver.java:363)
	... 46 more

WARNING: StandardWrapperValve[Faces Servlet]: Servlet.service() for servlet Faces Servlet threw exception
java.lang.NullPointerException
	[b]at br.com.k19.modelo.CarroRepository.buscaTodos(CarroRepository.java:20)
	at br.com.k19.controle.CarroBean.getCarros(CarroBean.java:36)[/b]
	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 javax.el.BeanELResolver.getValue(BeanELResolver.java:363)
	at com.sun.faces.el.DemuxCompositeELResolver._getValue(DemuxCompositeELResolver.java:176)
	at com.sun.faces.el.DemuxCompositeELResolver.getValue(DemuxCompositeELResolver.java:203)
	at com.sun.el.parser.AstValue.getValue(AstValue.java:140)
	at com.sun.el.parser.AstValue.getValue(AstValue.java:204)
	at com.sun.el.parser.AstEmpty.getValue(AstEmpty.java:66)
	at com.sun.el.parser.AstNot.getValue(AstNot.java:63)
	at com.sun.el.ValueExpressionImpl.getValue(ValueExpressionImpl.java:226)
	at com.sun.faces.facelets.el.TagValueExpression.getValue(TagValueExpression.java:109)
	at javax.faces.component.ComponentStateHelper.eval(ComponentStateHelper.java:194)
	at javax.faces.component.UIComponentBase.isRendered(UIComponentBase.java:462)
	at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1850)
	at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1859)
	at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1859)
	at com.sun.faces.application.view.FaceletViewHandlingStrategy.renderView(FaceletViewHandlingStrategy.java:443)
	at com.sun.faces.application.view.MultiViewHandler.renderView(MultiViewHandler.java:131)
	at com.sun.faces.lifecycle.RenderResponsePhase.execute(RenderResponsePhase.java:120)
	at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101)
	at com.sun.faces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:219)
	at javax.faces.webapp.FacesServlet.service(FacesServlet.java:647)
	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)

Bom pelo que entnedi ele está recebendo Null quando tenta chamar no CarroRepository o metodo buscaTodos(), mas no caso aquela parte do xhtml so deveria ser rederizada se o Bean não estiver vazio,certo?

Bom segue as classes: /carros.xhtml

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml"
	xmlns:h="http://java.sun.com/jsf/html"
	xmlns:f="http://java.sun.com/jsf/core"
	xmlns:ui="http://java.sun.com/jsf/facelets">

<h:head>
	<title>K19 Treinamentos</title>
</h:head>
<h:body>
	<h:form>
		<h:panelGrid columns="2">
			<h:outputLabel value="Marca: " for="campo-marca" />
			<h:inputText value="#{carroBean.carro.marca}" id="campo-marca" />

			<h:outputLabel value="Modelo: " for="campo-modelo" />
			<h:inputText value="#{carroBean.carro.modelo}" id="campo-modelo" />

			<h:commandButton value="Adicionar"
				action="#{carroBean.adicionaCarro}" />
		</h:panelGrid>
	</h:form>

	<h:panelGroup rendered="#{not empty carroBean.carros}">
		<h1>Lista de carros:</h1>
		<ul>
			<ui:repeat value="#{carroBean.carros}" var="carro">
				<li><h:outputText value="#{carro.marca} #{carro.modelo}" /></li>
			</ui:repeat>
		</ul>
	</h:panelGroup>
</h:body>
</html>

CarroBean

package br.com.k19.controle;

import br.com.k19.modelo.Carro;
import br.com.k19.modelo.CarroRepository;
import java.util.List;
import javax.faces.bean.ManagedBean;
import javax.faces.context.ExternalContext;
import javax.faces.context.FacesContext;
import javax.persistence.EntityManager;
import javax.servlet.http.HttpServletRequest;

@ManagedBean
public class CarroBean {

	private Carro carro = new Carro();

	public Carro getCarro() {
		return carro;
	}

	public void setCarro(Carro carro) {
		this.carro = carro;
	}

	public void adicionaCarro() {
		EntityManager manager = this.getEntityManager();
		CarroRepository repository = new CarroRepository(manager);

		repository.adiciona(this.carro);
		this.carro = new Carro();
	}

	public List<Carro> getCarros() {
		EntityManager manager = this.getEntityManager();
		CarroRepository repository = new CarroRepository(manager);
		return repository.buscaTodos();
	}

	private EntityManager getEntityManager() {
		FacesContext fc = FacesContext.getCurrentInstance();
		ExternalContext ec = fc.getExternalContext();
		HttpServletRequest request = (HttpServletRequest) ec.getRequest();
		EntityManager manager = (EntityManager)request.getAttribute("EntityManager");

		return manager;
	}

}

CarroRepository

package br.com.k19.modelo;

import java.util.List;
import javax.persistence.EntityManager;
import javax.persistence.Query;

public class CarroRepository {

	private EntityManager manager;

	public CarroRepository(EntityManager manager) {
		this.manager = manager;
	}

	public void adiciona(Carro carro) {
		this.manager.persist(carro);
	}

	public List<Carro> buscaTodos() {
		Query query = this.manager.createQuery("select x from Carro");
		return query.getResultList();
	}
}

Carro

package br.com.k19.modelo;

import java.io.Serializable;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;

@Entity
public class Carro implements Serializable {

	@Id @GeneratedValue
	private Long id;
	private String marca;
	private String modelo;
 
	public String getMarca() {
		return marca;
	}
	public void setMarca(String marca) {
		this.marca = marca;
	}
	public String getModelo() {
		return modelo;
	}
	public void setModelo(String modelo) {
		this.modelo = modelo;
	}


 }

EntityManager

package br.com.k19.filters;

import java.io.IOException;
import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.Persistence;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.annotation.WebFilter;

@WebFilter(servletNames={"Faces Servlet"})
public class JPAFilter implements Filter {

	private EntityManagerFactory factory;

	@Override
	public void init(FilterConfig filterConfig) throws ServletException {
			this.factory = Persistence.createEntityManagerFactory("K19-PU");
	}

	@Override
	public void destroy() {
		this.factory.close();
	}

	@Override
	public void doFilter(ServletRequest request, ServletResponse response,
			FilterChain chain) throws IOException, ServletException {

		// CHEGADA
		EntityManager manager = this.factory.createEntityManager();
		request.setAttribute("EntityManager", manager);
		manager.getTransaction().begin();
		// CHEGADA

		// FACES SERVLET
		chain.doFilter(request, response);
		// FACES SERVLET

		// SAÍDA
		try {
			manager.getTransaction().commit();
		} catch (Exception e) {
			manager.getTransaction().rollback();
		} finally {
			manager.close();
		}
		// SAÍDA
	}
 }

persistence.xml

http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd"> org.hibernate.ejb.HibernatePersistence

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