采用单态模式保证Hibernate的SessionFactory的单态

SessionFactoryBuilder.java

 

//由SessionFactoryBuilder的单态来保证SessionFactory的单态
public class SessionFactoryBuilder {
	
	private SessionFactory sessionFactory;
	private static SessionFactoryBuilder sfb;
	
	//空的私有构造函数
	private SessionFactoryBuilder(){
		
	}
	
	public static SessionFactoryBuilder instance(){
		if(sfb==null){
			sfb=new SessionFactoryBuilder();
		}
		return sfb;
	}
	
	public SessionFactory getSessionFactory()throws MessageException{
		if(sessionFactory==null){
			try {
				Configuration configuration=new Configuration().configure();
				sessionFactory=configuration.buildSessionFactory();
			} catch (HibernateException e) {
				System.out.println("初始化SessionFactory出现异常......"+e);
				throw new MessageException("初始化SessionFactory出现异常......");
			}
		}
		return sessionFactory;
	}

}