我按照Hibernate官方Documentation]创建了一个基本的Hibernate应用程序4.3.5最终版本 。当我执行应用程序时，我得到了hibernate.HibernateException：当‘hibernate.Dialect’没有设置时，对DialectResolutionInfo的访问不能为空，即使所有的配置在我看来都是正常的。
HibernateException：未设置'hibernate.dialect'时访问DialectResolutionInfo不能为null
我花了很长时间才解决了这个问题，结果是SessionFactory实例的创建方式有问题。我创建SessionFactory实例的实用程序类如下所示。
1package com.journaldev.hibernate.util;
2
3import org.hibernate.SessionFactory;
4import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
5import org.hibernate.cfg.Configuration;
6import org.hibernate.service.ServiceRegistry;
7
8public class SessionFactoryUtil {
9
10 private static SessionFactory sessionFactory;
11
12 private static SessionFactory buildSessionFactory() {
13 try {
14 // Create the SessionFactory from hibernate.cfg.xml
15 SessionFactory sessionFactory = new Configuration().configure("hibernate.cfg.xml")
16 .buildSessionFactory(new StandardServiceRegistryBuilder().build());
17
18 return sessionFactory;
19 }
20 catch (Throwable ex) {
21 // Make sure you log the exception, as it might be swallowed
22 System.err.println("Initial SessionFactory creation failed." + ex);
23 throw new ExceptionInInitializerError(ex);
24 }
25 }
26
27 public static SessionFactory getSessionFactory() {
28 if(sessionFactory == null) sessionFactory = buildSessionFactory();
29 return sessionFactory;
30 }
31}
我得到了以下堆栈跟踪：
1May 07, 2014 7:11:59 PM org.hibernate.cfg.Configuration getConfigurationInputStream
2INFO: HHH000040: Configuration resource: hibernate.cfg.xml
3May 07, 2014 7:12:00 PM org.hibernate.cfg.Configuration addResource
4INFO: HHH000221: Reading mappings from resource: employee.hbm.xml
5May 07, 2014 7:12:00 PM org.hibernate.cfg.Configuration doConfigure
6INFO: HHH000041: Configured SessionFactory: null
7May 07, 2014 7:12:00 PM org.hibernate.engine.jdbc.connections.internal.ConnectionProviderInitiator initiateService
8WARN: HHH000181: No appropriate connection provider encountered, assuming application will be supplying connections
9Initial SessionFactory creation failed.org.hibernate.HibernateException: Access to DialectResolutionInfo cannot be null when 'hibernate.dialect' not set
10Exception in thread "main" java.lang.NullPointerException
11 at com.journaldev.hibernate.main.HibernateMain.main(HibernateMain.java:38)
从日志中可以清楚地看到，Configuration类能够找到hibernate配置文件，并且它定义了hibernate.Dialt，因此exception没有任何意义。
修复HibernateException：未设置‘hibernate.Dialect’时，对DialectResolutionInfo的访问不能为空
经过一些研究和调试，我能够把它修好。官方文档中缺少的部分是，我们需要将配置属性应用到StandardServiceRegistryBuilder。当我将实用程序类更改为Below时，一切都非常顺利。
1package com.journaldev.hibernate.util;
2
3import org.hibernate.SessionFactory;
4import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
5import org.hibernate.cfg.Configuration;
6import org.hibernate.service.ServiceRegistry;
7
8public class SessionFactoryUtil {
9
10 private static SessionFactory sessionFactory;
11
12 private static SessionFactory buildSessionFactory() {
13 try {
14 // Create the SessionFactory from hibernate.cfg.xml
15 Configuration configuration = new Configuration();
16 configuration.configure("hibernate.cfg.xml");
17 System.out.println("Hibernate Configuration loaded");
18
19 //apply configuration property settings to StandardServiceRegistryBuilder
20 ServiceRegistry serviceRegistry = new StandardServiceRegistryBuilder().applySettings(configuration.getProperties()).build();
21 System.out.println("Hibernate serviceRegistry created");
22
23 SessionFactory sessionFactory = configuration
24 .buildSessionFactory(serviceRegistry);
25
26 return sessionFactory;
27 }
28 catch (Throwable ex) {
29 // Make sure you log the exception, as it might be swallowed
30 System.err.println("Initial SessionFactory creation failed." + ex);
31 throw new ExceptionInInitializerError(ex);
32 }
33 }
34
35 public static SessionFactory getSessionFactory() {
36 if(sessionFactory == null) sessionFactory = buildSessionFactory();
37 return sessionFactory;
38 }
39}
请注意StandardServiceRegistryBuilder（).applySettings调用，其中传递了配置属性。Hibernate仍在发展，每个版本都有很多变化，我觉得文档部分很滞后。我希望这将有助于有人解决这个问题，而不是浪费大量的时间调试。