Qual melhor forma de criar um EntityManager

Assuntos Gerais
#1

Bom dia pessoal, gostaria de saber a melhor forma de criar um EntityManager em um aplicacao web sem usar um (servidor EE e spring) apenas JPA +HIBERNATE no tomcat

Bom vamos la, eu estava fazendo deste jeito

 public void gravar(Object objeto) throws Exception {
        em =  emf.createEntityManager();
        try {
            em.getTransaction().begin();
            em.persist(objeto);
            em.getTransaction().commit();
        } catch (Exception e) {
            e.printStackTrace();
            em.getTransaction().rollback();
            throw e;
        } finally {
           em.close(); 
        }
    }

aqui sempre estava criando um EtityManager para cada serviço ,enquanto tava em desenvolvimento beleza…quando coloquei em produção começou a dar algum erros ai mudei para

    protected static EntityManager getEntityManager() {
        if (em == null) {
            emf = Persistence.createEntityManagerFactory("ControleFotoPU");
            em = emf.createEntityManager();
            return em;
        }
        return em;

    }

 public void gravar(Object objeto) throws Exception {
        em = getEntityManager();
        try {
            em.getTransaction().begin();
            em.persist(objeto);
            em.getTransaction().commit();
        } catch (Exception e) {
            e.printStackTrace();
            em.getTransaction().rollback();
            throw e;
    }

ja aqui optei por ter um EntityManger para aplicacao inteira,

Gostaria de saber dos mais esperiente, qual a melhor maneira, pois não gostaria de ter porblema futuros

Só um observação…

Mesmo com ess mudança de um erro estranho no tomcat em produção

veja

localizando o arquivo de logs /home//logs/catalina.out
Exemplo de comando para ver os logs:
$ tail -n 1000 /home//logs/catalina.out

log catalina.out:
javax.persistence.PersistenceException: org.hibernate.exception.JDBCConnectionException: could not execute query
at org.hibernate.ejb.AbstractEntityManagerImpl.convert(AbstractEntityManagerImpl.java:1214)
at org.hibernate.ejb.AbstractEntityManagerImpl.convert(AbstractEntityManagerImpl.java:1147)
at org.hibernate.ejb.QueryImpl.getResultList(QueryImpl.java:255)
at org.hibernate.ejb.criteria.CriteriaQueryCompiler$3.getResultList(CriteriaQueryCompiler.java:260)
at persistencias.Dao.listar(Dao.java:85)
at negocios.PessoaBO.listar(PessoaBO.java:56)
at apresentacao.AcessoMB.iniciarSistema(AcessoMB.java:170)
at apresentacao.AcessoMB.(AcessoMB.java:38)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
at java.lang.reflect.Constructor.newInstance(Constructor.java:513)
at java.lang.Class.newInstance0(Class.java:355)
at java.lang.Class.newInstance(Class.java:308)
at com.sun.faces.mgbean.BeanBuilder.newBeanInstance(BeanBuilder.java:188)
at com.sun.faces.mgbean.BeanBuilder.build(BeanBuilder.java:102)
at com.sun.faces.mgbean.BeanManager.createAndPush(BeanManager.java:405)
at com.sun.faces.mgbean.BeanManager.create(BeanManager.java:267)
at com.sun.faces.el.ManagedBeanELResolver.getValue(ManagedBeanELResolver.java:86)
at javax.el.CompositeELResolver.getValue(CompositeELResolver.java:54)
at com.sun.faces.el.FacesCompositeELResolver.getValue(FacesCompositeELResolver.java:72)
at org.apache.el.parser.AstIdentifier.getValue(AstIdentifier.java:61)
at org.apache.el.parser.AstValue.getValue(AstValue.java:107)
at org.apache.el.ValueExpressionImpl.getValue(ValueExpressionImpl.java:186)
at com.sun.faces.facelets.el.TagValueExpression.getValue(TagValueExpression.java:102)
at javax.faces.component.ComponentStateHelper.eval(ComponentStateHelper.java:190)
at javax.faces.component.ComponentStateHelper.eval(ComponentStateHelper.java:178)
at javax.faces.component.UIOutput.getValue(UIOutput.java:168)
at org.primefaces.util.ComponentUtils.getStringValueToRender(ComponentUtils.java:66)
at org.primefaces.component.inputtext.InputTextRenderer.encodeMarkup(InputTextRenderer.java:92)
at org.primefaces.component.inputtext.InputTextRenderer.encodeEnd(InputTextRenderer.java:53)
at javax.faces.component.UIComponentBase.encodeEnd(UIComponentBase.java:878)
at com.sun.faces.renderkit.html_basic.HtmlBasicRenderer.encodeRecursive(HtmlBasicRenderer.java:295)
at com.sun.faces.renderkit.html_basic.GridRenderer.renderRow(GridRenderer.java:185)
at com.sun.faces.renderkit.html_basic.GridRenderer.encodeChildren(GridRenderer.java:129)
at javax.faces.component.UIComponentBase.encodeChildren(UIComponentBase.java:848)
at org.primefaces.renderkit.CoreRenderer.renderChild(CoreRenderer.java:58)
at org.primefaces.renderkit.CoreRenderer.renderChildren(CoreRenderer.java:46)
at org.primefaces.component.panel.PanelRenderer.encodeContent(PanelRenderer.java:225)
at org.primefaces.component.panel.PanelRenderer.encodeMarkup(PanelRenderer.java:148)
at org.primefaces.component.panel.PanelRenderer.encodeEnd(PanelRenderer.java:75)
at javax.faces.component.UIComponentBase.encodeEnd(UIComponentBase.java:878)
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1620)
at javax.faces.render.Renderer.encodeChildren(Renderer.java:168)
at javax.faces.component.UIComponentBase.encodeChildren(UIComponentBase.java:848)
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1613)
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1616)
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1616)
at com.sun.faces.application.view.FaceletViewHandlingStrategy.renderView(FaceletViewHandlingStrategy.java:380)
at com.sun.faces.application.view.MultiViewHandler.renderView(MultiViewHandler.java:126)
at com.sun.faces.lifecycle.RenderResponsePhase.execute(RenderResponsePhase.java:127)
at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101)
at com.sun.faces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:139)
at javax.faces.webapp.FacesServlet.service(FacesServlet.java:313)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.primefaces.webapp.filter.FileUploadFilter.doFilter(FileUploadFilter.java:79)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:128)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:293)
at org.apache.jk.server.JkCoyoteHandler.invoke(JkCoyoteHandler.java:190)
at org.apache.jk.common.HandlerRequest.invoke(HandlerRequest.java:291)
at org.apache.jk.common.ChannelSocket.invoke(ChannelSocket.java:769)
at org.apache.jk.common.ChannelSocket.processConnection(ChannelSocket.java:698)
at org.apache.jk.common.ChannelSocket$SocketConnection.runIt(ChannelSocket.java:891)
at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:690)
at java.lang.Thread.run(Thread.java:619)
Caused by: org.hibernate.exception.JDBCConnectionException: could not execute query
at org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:99)
at org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:66)
at org.hibernate.loader.Loader.doList(Loader.java:2536)
at org.hibernate.loader.Loader.listIgnoreQueryCache(Loader.java:2276)
at org.hibernate.loader.Loader.list(Loader.java:2271)
at org.hibernate.loader.hql.QueryLoader.list(QueryLoader.java:452)
at org.hibernate.hql.ast.QueryTranslatorImpl.list(QueryTranslatorImpl.java:363)
at org.hibernate.engine.query.HQLQueryPlan.performList(HQLQueryPlan.java:196)
at org.hibernate.impl.SessionImpl.list(SessionImpl.java:1268)
at org.hibernate.impl.QueryImpl.list(QueryImpl.java:102)
at org.hibernate.ejb.QueryImpl.getResultList(QueryImpl.java:246)
... 69 more
Caused by: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: The last packet successfully received from the server was 39,125,567 milliseconds ago. The last packet sent successfully to the server was 39,125,567 milliseconds ago. is longer than the server configured value of 'wait_timeout'. You should consider either expiring and/or testing connection validity before use in your application, increasing the server configured values for client timeouts, or using the Connector/J connection property 'autoReconnect=true' to avoid this problem.
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
at java.lang.reflect.Constructor.newInstance(Constructor.java:513)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:407)
at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1116)
at com.mysql.jdbc.MysqlIO.send(MysqlIO.java:3358)
at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:1970)
at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2150)
at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2626)
at com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:2119)
at com.mysql.jdbc.PreparedStatement.executeQuery(PreparedStatement.java:2281)
at org.hibernate.jdbc.AbstractBatcher.getResultSet(AbstractBatcher.java:208)
at org.hibernate.loader.Loader.getResultSet(Loader.java:1953)
at org.hibernate.loader.Loader.doQuery(Loader.java:802)
at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:274)
at org.hibernate.loader.Loader.doList(Loader.java:2533)
... 77 more
Caused by: java.net.SocketException: Broken pipe
at java.net.SocketOutputStream.socketWrite0(Native Method)
at java.net.SocketOutputStream.socketWrite(SocketOutputStream.java:92)
at java.net.SocketOutputStream.write(SocketOutputStream.java:136)
at java.io.BufferedOutputStream.flushBuffer(BufferedOutputStream.java:65)
at java.io.BufferedOutputStream.flush(BufferedOutputStream.java:123)
at com.mysql.jdbc.MysqlIO.send(MysqlIO.java:3339)
... 87 more

pois o meu listar

    public List<? extends Object> listar(Class classe) throws Exception {
        em = getEntityManager();
        List<? extends Object> objetos = new ArrayList<Object>();
        try {
            CriteriaBuilder queryBuilder = em.getCriteriaBuilder();
            CriteriaQuery<? extends Object> cq = queryBuilder.createQuery(classe);
            Root<? extends Object> root = cq.from(classe);
            TypedQuery<? extends Object> tq = em.createQuery(cq);
            objetos = tq.getResultList();
        } catch (Exception e) {
            e.printStackTrace();
            throw e;
        } 
        return objetos;
    }

funciona perfeitamente em desenvolvimento

obrigado pessoal

#2

Ouvi alguma coisa que isso poderia ser a solução

<property name="hibernate.c3p0.min_size">1</property>
<property name="hibernate.c3p0.max_size">20</property>
<property name="hibernate.c3p0.timeout">30</property>
<property name="hibernate.c3p0.idle_test_period">100</property>

porem uma coisa nada haver começou a acontecer , apos mudar isto na minh aplicacao, as imagens (fotos) que é um campo na minha tadatable nao aparece mais, só mudei isso

#3

Fora do Container JavaEE, concerteza e a JPAUtil abrindo e fechando conexões em um Interceptor.

Da uma Olhada nos dois links:
http://www.guj.com.br/java/223449-entitymanagerfactory/2
http://code.google.com/p/jpautil/downloads/detail?name=ExemploJPAUtil.zip&can=2&q=

#4

eu tava criando assim como vc pode observar ,mais tava dando um monte de pau…

parece que nao fechava direito…

#5

No livro EJB3 em ação fala que a melhor maneira de usar o hibernate fora de um Container JavaEE é usar o padrao ThreadLocal,veja


/**
 *
 * @author erick
 */
public class HibernateUtil {
    private static EntityManagerFactory emf;
    public static final ThreadLocal<EntityManager> threadLocal = new ThreadLocal<EntityManager>();

    public static EntityManagerFactory getEntityManagerFactory(){
        if(emf == null){
            emf = Persistence.createEntityManagerFactory("ControleFotoPU");
        }
        return emf;
    }

    public static EntityManager getEntityManager(){
        EntityManager entityManager = threadLocal.get();
        if(entityManager == null){
            entityManager = getEntityManagerFactory().createEntityManager();
            threadLocal.set(entityManager);
        }
        return entityManager;

    }


}

mudei minha aplicação assim e POR ENQUANTO ainda não deu nehum erro

#6