Hibernate升级到5.2-创建会话工厂并替换PersistentClass以获取实体类属性

Question

我当前正在将Hibernate版本升级到最新版本5.2.10。我将HibernateUtil中的代码替换为SessionFactory创建。

4.3.11 Final（Previous） ：

 public class HibernateUtil {
   private HibernateUtil() {}

   private static SessionFactory sessionFactory;

    private static Configuration configuration;

    public static Configuration getConfiguration() {
        return configuration;
    }
    private static SessionFactory buildSessionFactory() {
        try {
                     if(sessionFactory == null) {
                        configuration = new Configuration();
                        configuration.configure("hibernate.cfg.xml");
                        ServiceRegistry serviceRegistry = new StandardServiceRegistryBuilder()
                                .applySettings(configuration.getProperties()).build();
                        sessionFactory = configuration
                                .buildSessionFactory(serviceRegistry);
                     }
            return sessionFactory;
        }
        catch (Throwable ex) {
            throw new ExceptionInInitializerError(ex);
        }

    }
    public static SessionFactory getSessionFactory() {
        return buildSessionFactory();
    }

    public static Session getSession() {
        Session hibernateSession = getSessionFactory().getCurrentSession();
        return hibernateSession;
      }

    public static void shutdown() {
       getSessionFactory().close();
    }
}

5.2.10决赛（新）：

public class HibernateUtil {
  private static StandardServiceRegistry registry;
  private static SessionFactory sessionFactory;

   public static SessionFactory getSessionFactory() {
        return buildSessionFactory();
   }

  public static SessionFactory buildSessionFactory() {
    if (sessionFactory == null) {
      try {
        registry = new StandardServiceRegistryBuilder().configure("hibernate.cfg.xml").build();
        MetadataSources sources = new MetadataSources(registry);
        Metadata metadata = sources.getMetadataBuilder().build();
        sessionFactory = metadata.getSessionFactoryBuilder().build();
      } catch (Exception e) {
        e.printStackTrace();
        shutdown();
      }
    }
    return sessionFactory;
  }

public static Session getSession() {
        Session hibernateSession = getSessionFactory().getCurrentSession();
        return hibernateSession;
      }

  public static void shutdown() {
    if (registry != null) {
      StandardServiceRegistryBuilder.destroy(registry);
    }
  }
}

现在，我有了一个方法，该方法通过将数据库表名称作为字符串传递来获取列名称列表。我之前在4.3.11.Final中这样做过：

public static List<String> getColumnNames(String tableName) {

        List<String> columnList=null;

        Map<String, ClassMetadata> map = HibernateUtil.getSessionFactory().getAllClassMetadata();
        Iterator<Entry<String, ClassMetadata>>  itr =  map.entrySet().iterator();

        while(itr.hasNext()){

            ClassMetadata classMetaData = itr.next().getValue();
            AbstractEntityPersister aep = (AbstractEntityPersister) classMetaData;

            if(aep.getTableName().split("\\.")[1].equalsIgnoreCase(tableName)){

                columnList = new ArrayList<String>();
                String[] propertyNames = classMetaData.getPropertyNames();

                for(String property : propertyNames){
                        try {
                            PersistentClass persistentClass = HibernateUtil .getConfiguration().getClassMapping(classMetaData.getEntityName());
                            String clmName =  ((Column) persistentClass.getProperty(property).getColumnIterator().next()).getName();
                            columnList.add(clmName);
                        } catch(NoSuchElementException e){
                            log.error("Element not found idenfied as : "+property);
                        } catch(Exception e){
                            log.error(e.getMessage());
                        }
                }
                break;
            }
        }

        return columnList;
    }

现在，升级后，它显示方法getAllClassMetadata已弃用，并且很难获取PersistentClass对象。我在这里看到了类似的问题，但我无法确切地找到解决方案。我必须更改当前代码的哪一部分，才能使getColumnNames（）方法完全像以前一样工作。我参考了文档，并说要使用，
EntityManagerFactory.getMetamodel()但是我找不到合适的参考示例。还需要为此更改SessionFactory创建机制吗？

Answer 1

好吧，最后我感谢弗拉德的文章。我获取了集成器代码，未做任何更改，并修改了我HibernateUtil的getColumns()方法。所以这是我的代码：

SessionFactory的创建：

public class HibernateUtil {

    private static final SessionFactory sessionFactory = buildSessionFactory();

    public static SessionFactory getSessionFactory() {
        return buildSessionFactory();
    }

    private static SessionFactory buildSessionFactory() {
        final BootstrapServiceRegistry bootstrapServiceRegistry = new BootstrapServiceRegistryBuilder().enableAutoClose()
                .applyIntegrator(MetadataExtractorIntegrator.INSTANCE).build();

        final StandardServiceRegistry serviceRegistry = new StandardServiceRegistryBuilder(bootstrapServiceRegistry).configure().build();
        return new MetadataSources(serviceRegistry).buildMetadata().buildSessionFactory();
    }

    public static Session getSession() {
        Session hibernateSession = getSessionFactory().getCurrentSession();
        return hibernateSession;
    }

    public static void shutdown() {
        getSessionFactory().close();
    }
}

元数据提取器（获取列名称）：

public static List<String> getColumnNames(String tableName) {

    List<String> columnList = new ArrayList<>();

    for (Namespace namespace : MetadataExtractorIntegrator.INSTANCE.getDatabase().getNamespaces()) {
        for (Table table : namespace.getTables()) {
            if (table.getName().equalsIgnoreCase(lookupTableName)) {
                Iterator<Column> iterator = table.getColumnIterator();
                while (iterator.hasNext()) {
                    columnList.add(iterator.next().getName());
                }
                break;
            }
        }
        if (!columnList.isEmpty())
            break;
    }
    return columnList;
}