Question

这些是错误中涉及的类（我不使用Entreprise Java Bean）：

@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;

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().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;
    }

}

所以，例外是：JTA EntityManager不能使用getTransaction（）

Answer 1

最后，我只是在persistence.xml文件的源代码中将'JTA'替换为'RESOURCE_LOCAL'：

错误：JTA EntityManager无法使用getTransaction（）

1 个答案: