hibernate - createEntityManager 在 org.hibernate.engine.transaction.internal.jta.JtaStatusHelper.getStatus 抛出 java.lang.NullPointerException

Question

当我部署我的 hibernate 应用程序时，我得到了这个堆栈跟踪

java.lang.NullPointerException
    at org.hibernate.engine.transaction.internal.jta.JtaStatusHelper.getStatus(JtaStatusHelper.java:72) [hibernate-core-4.0.0.Beta1.jar:4.0.0.Beta1]
    at org.hibernate.engine.transaction.internal.jta.JtaStatusHelper.isActive(JtaStatusHelper.java:114) [hibernate-core-4.0.0.Beta1.jar:4.0.0.Beta1]
    at org.hibernate.engine.transaction.internal.jta.CMTTransaction.join(CMTTransaction.java:149) [hibernate-core-4.0.0.Beta1.jar:4.0.0.Beta1]
    at org.hibernate.ejb.AbstractEntityManagerImpl.joinTransaction(AbstractEntityManagerImpl.java:1197) [hibernate-entitymanager-4.0.0.Beta1.jar:4.0.0.Beta1]
    at org.hibernate.ejb.AbstractEntityManagerImpl.postInit(AbstractEntityManagerImpl.java:170) [hibernate-entitymanager-4.0.0.Beta1.jar:4.0.0.Beta1]
    at org.hibernate.ejb.EntityManagerImpl.<init>(EntityManagerImpl.java:90) [hibernate-entitymanager-4.0.0.Beta1.jar:4.0.0.Beta1]
    at org.hibernate.ejb.EntityManagerFactoryImpl.createEntityManager(EntityManagerFactoryImpl.java:112) [hibernate-entitymanager-4.0.0.Beta1.jar:4.0.0.Beta1]
    at org.hibernate.ejb.EntityManagerFactoryImpl.createEntityManager(EntityManagerFactoryImpl.java:107) [hibernate-entitymanager-4.0.0.Beta1.jar:4.0.0.Beta1]
    at com.mycompany.myapp.common.persistence.HibernateUtil.<clinit>(HibernateUtil.java:53) [classes:]
    at com.mycompany.myapp.common.businessobjects.ServerSettings.GetServerSettings(ServerSettings.java:247) [classes:]
    at com.mycompany.myapp.common.servlet.SecurityFilter.init(SecurityFilter.java:55) [classes:]
    at org.apache.catalina.core.ApplicationFilterConfig.getFilter(ApplicationFilterConfig.java:447) [jbossweb-7.0.0.CR4.jar:7.0.0.Final]
    at org.apache.catalina.core.StandardContext.filterStart(StandardContext.java:3245) [jbossweb-7.0.0.CR4.jar:7.0.0.Final]
    at org.apache.catalina.core.StandardContext.start(StandardContext.java:3836) [jbossweb-7.0.0.CR4.jar:7.0.0.Final]
    at org.jboss.as.web.deployment.WebDeploymentService.start(WebDeploymentService.java:70) [jboss-as-web-7.0.0.Final.jar:7.0.0.Final]
    at org.jboss.msc.service.ServiceControllerImpl$StartTask.run(ServiceControllerImpl.java:1765)
    at org.jboss.msc.service.ServiceControllerImpl$ClearTCCLTask.run(ServiceControllerImpl.java:2291)
    at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886) [:1.6.0_26]
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908) [:1.6.0_26]
    at java.lang.Thread.run(Thread.java:680) [:1.6.0_26]

它在我的 HibernateUtil 类中遇到了 NPE，第 53 行是创建 EntityManager 的行 - 看起来 createEntityManager() 返回空值。代码看起来像

private static EntityManagerFactory entityManagerFactory = null;
private static EntityManager entityManager = null;

static {
    try {

        entityManagerFactory = Persistence.createEntityManagerFactory("primary");
        entityManager = entityManagerFactory.createEntityManager();

我的persistence.xml 看起来像

<?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="primary"> <jta-data-source>java:jboss/datasources/MySqlDS</jta-data-source>

  <properties>
     <property name="hibernate.dialect" value="org.hibernate.dialect.MySQLDialect"/>
     <property name="hibernate.ejb.interceptor.session_scoped" value="com.mycompany.myapp.common.persistence.BusinessObjectInterceptor"/>
           </properties>

为什么 createEntityManager() 给 NPE 的任何想法？

Answer 1

如果您正在使用 Hibernate 4 并尝试创建 EntityManagerFactory手动(或 SessionFactory)声明为 <jta-datasource> ，您必须在 persistence.xml 上设置一个属性叫 hibernate.transaction.jta.platform .
用于在 JBoss 7 上使用

<property name="hibernate.transaction.jta.platform" value="org.hibernate.service.jta.platform.internal.JBossAppServerJtaPlatform" />

我在 Hibernate Docs 上找到了有关此属性的信息