关于hibernate空指针异常的问题

Question

import org.hibernate.Session;

import org.hibernate.SessionFactory;

import org.hibernate.Transaction;

import org.hibernate.cfg.Configuration;

import org.junit.Test;

import com.opensymphony.xwork2.interceptor.annotations.After;

import com.opensymphony.xwork2.interceptor.annotations.Before;

public class HibernateUtil {

private SessionFactory sessionFactory;

private Session session;

private Transaction transaction;

@Before

public void init() {

// 创建配置对象

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

// 创建回话工厂对象

sessionFactory = config.buildSessionFactory();

// 会话对象

session = sessionFactory.openSession();

// 开启事务

transaction = session.beginTransaction();

}

@After

public void destory() {

transaction.commit();// 提交事务

session.close();// 关闭会话

sessionFactory.close();// 关闭会话工厂

}

@Test

public void testSaveUser(){

User u=(User)session.get(User.class, 100000);

System.out.println(u.getUsername());

}

}

 大佬们，求解为什么会出现java.lang.NullPointerException，提示是User u=(User)session.get(User.class, 100000);这个地方出错，但是我排查不出来。。