java - 返回 Hibernate 4.3 的 SessionFactory Singleton 对象

Question

我正在使用 Hibernate 4.3。我正在尝试从 HibernateUtil 类中获取 SessionFactory 对象。我试图为整个应用程序只获取一个 SessionFactory 对象，即应用程序的 Singleton 对象。

下面是我目前的代码，我想把它做成单例类。

HibernateUtil.java

public class HibernateUtil {

    private static SessionFactory sessionFactory;
    private static StandardServiceRegistry serviceRegistry; 

    public static SessionFactory getSessionFactory() {
      Configuration configuration = new Configuration();
      configuration.configure();
      serviceRegistry = new StandardServiceRegistryBuilder().applySettings(configuration.getProperties()).build();
      sessionFactory = configuration.buildSessionFactory(serviceRegistry);
      return sessionFactory;
  }

}

请为此建议或提供示例代码。 谢谢。

Answer 1

只应用单例模式

public class HibernateUtil {

  private static StandardServiceRegistry serviceRegistry; 
  private volatile static SessionFactory INSTANCE = null;

  public static SessionFactory getSessionFactory() {
    if(INSTANCE==null){
      createSessionFactory();
    }
    return sessionFactory;
  }

  private synchronized static void createSessionFactory() {
    if(INSTANCE!=null){return;}

    Configuration configuration = new Configuration();
    configuration.configure();

    serviceRegistry = new StandardServiceRegistryBuilder().applySettings(configuration.getProperties()).build();
    INSTANCE = configuration.buildSessionFactory(serviceRegistry);
  }
}

编辑:修正了一个逗号拼写错误