错误：JTA EntityManager不能使用getTransaction（） [英] Error: A JTA EntityManager cannot use getTransaction()
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问题描述
这些是涉及错误的类（我没有使用Entreprise Java Beans）：
@WebListener
public class EMF实现ServletContextListener {
private static EntityManagerFactory emf;
private final String PERSISTENCE_UNIT_NAME =ldnr;
@Override
public void contextInitialized（ServletContextEvent event）{
Map< String，String> properties = new HashMap<>（）;
properties.put（javax.persistence.jdbc.user，root）;
properties.put（javax.persistence.jdbc.password，1234512345）;
emf = Persistence.createEntityManagerFactory（PERSISTENCE_UNIT_NAME，properties）;
}
@Override
public void contextDestroyed（ServletContextEvent event）{
emf.close（）;
$ b $ public static EntityManager createEntityManager（）{
if（emf == null）{
throw new IllegalStateException（Context is not initialized yet。）;
}
return emf.createEntityManager（）;
}
}
包fr.ldnr.daoImpl;
这是使用实体管理器的类。
public abstract class DAOFactoryImpl implements DAOFactory {
private final EntityManager em;
public DAOFactoryImpl（）{
em = EMF.createEntityManager（）;
}
@Override
@Transactional
@TransactionAttribute（TransactionAttributeType.REQUIRED）
public void save（Object o）throws Exception {
em.getTransaction（）（）开始。
em.persist（o）;
em.flush（）;
em.clear（）;
em.close（）;
}
@Override
@Transactional
@TransactionAttribute（TransactionAttributeType.REQUIRED）
public Object update（Object o）throws Exception {
o = em.merge（o）;
em.flush（）;
em.clear（）;
em.close（）;
return o;
}
@Override
@Transactional
@TransactionAttribute（TransactionAttributeType.REQUIRED）
public Object find（Class myClass，long id）throws Exception { b $ b Object o = em.find（myClass，id）;
em.clear（）;
em.close（）;
return o;
}
@Override
@Transactional
@TransactionAttribute（TransactionAttributeType.REQUIRED）
public List< Object> findAll（Class myClass）抛出Exception {
List< Object> objectsList = em.createQuery（select * from+ myClass.getClass（）。getSimpleName（））。getResultList（）;
返回objectsList;
}
@Override
@Transactional
@TransactionAttribute（TransactionAttributeType.REQUIRED）
public void delete（Object o）throws Exception {
em.remove（O）;
em.flush（）;
em.clear（）;
em.close（）;
}
@Override
@Transactional
@TransactionAttribute（TransactionAttributeType.REQUIRED）
public Object queryObject（String query）throws Exception {
Object o = em.createQuery（query）.getSingleResult（）;
em.flush（）;
em.clear（）;
em.close（）;
return o;
}
@Override
@Transactional
@TransactionAttribute（TransactionAttributeType.REQUIRED）
public List< Object> queryObjects（String query）抛出Exception {
List< Object> objectsList = em.createQuery（query）.getResultList（）;
em.flush（）;
em.clear（）;
em.close（）;
返回objectsList;
$ b @Override
@Transactional
@TransactionAttribute（TransactionAttributeType.REQUIRED）
public long count（Class entityClass）throws Exception {
Object o = em.createQuery（select count（*）from+ entityClass.getSimpleName（））;
em.clear（）;
em.close（）;
return（Long）o;
属性additionalProperties（）{
属性properties = new Properties（）;
properties.setProperty（hibernate.dialect，org.hibernate.dialect.MySQLDialect）;
返回属性;
}
}
所以，例外是：A JTA EntityManager不能使用getTransaction（）解决方案
最后，我简单地用'RESOURCE_LOCAL'替换'JTA'中的源代码中的持久性.xml文件：
These are the classes implicated in the error (I'm not Using The Entreprise Java Beans):
@WebListener
public class EMF implements ServletContextListener {
private static EntityManagerFactory emf;
private final String PERSISTENCE_UNIT_NAME = "ldnr";
@Override
public void contextInitialized(ServletContextEvent event) {
Map<String, String> properties = new HashMap<>();
properties.put("javax.persistence.jdbc.user", "root");
properties.put("javax.persistence.jdbc.password", "1234512345");
emf = Persistence.createEntityManagerFactory(PERSISTENCE_UNIT_NAME, properties);
}
@Override
public void contextDestroyed(ServletContextEvent event) {
emf.close();
}
public static EntityManager createEntityManager() {
if (emf == null) {
throw new IllegalStateException("Context is not initialized yet.");
}
return emf.createEntityManager();
}
}
package fr.ldnr.daoImpl;
This is the class using the entity manager.
public abstract class DAOFactoryImpl implements DAOFactory {
private final EntityManager em;
public DAOFactoryImpl() {
em = EMF.createEntityManager();
}
@Override
@Transactional
@TransactionAttribute(TransactionAttributeType.REQUIRED)
public void save(Object o) throws Exception {
em.getTransaction().begin();
em.persist(o);
em.flush();
em.clear();
em.close();
}
@Override
@Transactional
@TransactionAttribute(TransactionAttributeType.REQUIRED)
public Object update(Object o) throws Exception {
o = em.merge(o);
em.flush();
em.clear();
em.close();
return o;
}
@Override
@Transactional
@TransactionAttribute(TransactionAttributeType.REQUIRED)
public Object find(Class myClass, long id) throws Exception {
Object o = em.find(myClass, id);
em.clear();
em.close();
return o;
}
@Override
@Transactional
@TransactionAttribute(TransactionAttributeType.REQUIRED)
public List<Object> findAll(Class myClass) throws Exception {
List<Object> objectsList = em.createQuery("select * from " + myClass.getClass().getSimpleName()).getResultList();
return objectsList;
}
@Override
@Transactional
@TransactionAttribute(TransactionAttributeType.REQUIRED)
public void delete(Object o) throws Exception {
em.remove(o);
em.flush();
em.clear();
em.close();
}
@Override
@Transactional
@TransactionAttribute(TransactionAttributeType.REQUIRED)
public Object queryObject(String query) throws Exception {
Object o = em.createQuery(query).getSingleResult();
em.flush();
em.clear();
em.close();
return o;
}
@Override
@Transactional
@TransactionAttribute(TransactionAttributeType.REQUIRED)
public List<Object> queryObjects(String query) throws Exception {
List<Object> objectsList = em.createQuery(query).getResultList();
em.flush();
em.clear();
em.close();
return objectsList;
}
@Override
@Transactional
@TransactionAttribute(TransactionAttributeType.REQUIRED)
public long count(Class entityClass) throws Exception {
Object o = em.createQuery("select count(*) from " + entityClass.getSimpleName());
em.clear();
em.close();
return (Long) o;
}
Properties additionalProperties() {
Properties properties = new Properties();
properties.setProperty("hibernate.dialect", "org.hibernate.dialect.MySQLDialect");
return properties;
}
}
So, the exception is: A JTA EntityManager cannot use getTransaction()
解决方案
Finally I simply replaced 'JTA' with 'RESOURCE_LOCAL' in this source code in the persistence.xml file:
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