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类中命中NPE，第53行是一条创建EntityManager的行 - 看起来createEntityManager（）返回null。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（）给出NPE的想法？

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>，则必须在{{1}上设置一个属性叫persistence.xml。适用于JBoss 7

hibernate.transaction.jta.platform

我在Hibernate Docs

找到了这个属性

Answer 2

Stacktrace清楚地表明Hibernate无法加入JTA事务。此外，<jta-data-source>和Persistence.createEntityManagerFactory()的组合看起来很奇怪 - 支持JTA的EntityManager通常由应用程序服务器创建，并通过JNDI从中获取。

如果您确实想要使用资源本地事务而不是JTA，则需要声明<non-jta-data-source>。

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

2 个答案: