java - hibernate SessionFactory 不起作用

Question

我在 hibernate 时遇到问题，但我不明白这个问题到底是什么如果你有什么想法？

private SessionFactory sessionFactory;
@SuppressWarnings("unchecked")
public List<Customer> listCustomer() {
    return sessionFactory.getCurrentSession().createQuery("FROM customer").list();
}

Main.java

public class Main {

public static void main(String[] args) {

    CustomerDaoImpl dao=new CustomerDaoImpl();

    for(int i=0; i<dao.listCustomer().size(); i++){
        System.out.println(i);
    }   
   }
 }

错误

Exception in thread "main" java.lang.NullPointerException
at com.apps.dao.CustomerDaoImpl.listCustomer(CustomerDaoImpl.java:37)
at com.apps.dao.Main.main(Main.java:8)

Answer 1

您必须初始化您的sessionFactory。在早期的 hibernate 版本中，您是这样做的

SessionFactory sessionFactory = new Configuration().configure().buildSessionFactory();

从 4.3.0 版本开始。你必须这样做

Configuration configuration = new Configuration().configure();
StandardServiceRegistryBuilder builder = new StandardServiceRegistryBuilder().
applySettings(configuration.getProperties());
SessionFactory sessionFactory = configuration.buildSessionFactory(builder.build());