我是Java的Hibernate框架的新手。 我有一個HibernateUtil
類的代碼,我不明白INSTANCE
來自哪裏。 它持有的HibernateUtil
類的情況下,如何?什麼是HibernateUtil中的INSTANCE?
的代碼是這樣的......
import java.util.Properties;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;
import org.hibernate.service.ServiceRegistryBuilder;
public enum HibernateUtil {
INSTANCE; // what about this???
public static SessionFactory sessionFactory = null;
private synchronized SessionFactory initialiseSessionFactory() {
if (sessionFactory == null) {
Configuration config = new Configuration();
config.addAnnotatedClass(demo1.class);
config.addAnnotatedClass(demo2.class);
config.configure();
//get the properties from Hibernate configuration file
Properties configProperties = config.getProperties();
ServiceRegistryBuilder serviceRegisteryBuilder = new ServiceRegistryBuilder();
ServiceRegistry serviceRegistry = serviceRegisteryBuilder.applySettings(configProperties).buildServiceRegistry();
sessionFactory = config.buildSessionFactory(serviceRegistry);
}
return sessionFactory;
}
public Session getSession() {
Session hibernateSession = null;
if (sessionFactory == null) {
hibernateSession = initialiseSessionFactory().openSession();
} else {
hibernateSession = sessionFactory.openSession();
}
return hibernateSession;
}
}
但是沒有'INSTANSE = new HibernateUtil();',那麼它從哪裏來,爲什麼HibernateUtil是「枚舉」? –
它隱含地完成:這是一個枚舉類型 –
你給我一個鏈接,我可以從這裏理解這件事......關於枚舉。 –