Caused by: org.hibernate.HibernateException: Connection cannot be null when 'hibernate.dialect' not set

docs.jboss.org文档示例代码：（http://docs.jboss.org/hibernate/annotations/3.5/reference/en/html_single/）

    static {
        try {
            sessionFactory = new AnnotationConfiguration()
                    .configure().buildSessionFactory();
        } catch (Throwable ex) {
            // Log exception!
            throw new ExceptionInInitializerError(ex);
        }
    }

测试时出现Caused by: org.hibernate.HibernateException: Connection cannot be null when 'hibernate.dialect' not set

自己依赖的是hibernate-core-4.2.7.Final.jar

改成：

Configuration cfg = new Configuration().configure();  
ServiceRegistry serviceRegistry= new ServiceRegistryBuilder().applySettings(cfg.getProperties()).buildServiceRegistry();  
sessionFactory = cfg.buildSessionFactory(serviceRegistry);  

Hibernate官网上没找到说明。网上找的。