package cn.siggy.util;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
import org.hibernate.cfg.Configuration;

public class HibernateUtil {
	private static Configuration cfg=null;
	private static SessionFactory factory=null;
	private static Session session = null;
	static{
		cfg = new Configuration().configure();
		factory = cfg.buildSessionFactory(new StandardServiceRegistryBuilder()
		.applySettings(cfg.getProperties()).build());
	}
	public static Session getSession(){
		if(factory!=null)
			return session=factory.openSession();
		factory=cfg.buildSessionFactory(new StandardServiceRegistryBuilder()
		.applySettings(cfg.getProperties()).build());
		return session=factory.openSession();
	}
	public static void closeSession(){
		if(session!=null&&session.isOpen())
			session.close();
	}
}
　

package cn.siggy.test;

import java.util.List;

import org.hibernate.Session;
import org.hibernate.Transaction;
import org.junit.Test;

import cn.siggy.pojo.User;
import cn.siggy.util.HibernateUtil;

public class HibernateTest {
	@Test
	public void testSave(){
		Session session=null;
		Transaction tx=null;
		User user=null;
		try {
			session = HibernateUtil.getSession();
			tx = session.beginTransaction();
			//构造对象--瞬时状态
			user = new User();
			user.setName("刘德华");
			user.setPwd("2222");
			//持久状态，user被session管理，并且id有值--oid,即对象id
			session.save(user);
			//在持久状态下；脏数据检查：当提交事务，清理缓存时发现session中数据
			//和数据库中数据不一致时，将会把session中的数据更新到数据库中
			user.setName("学友");
			//在保存以后 再修改对象 那么将会产生2条sql语句，那么效率较低，建议在save前修改
			session.flush();
			tx.commit();
		} catch (Exception e) {
			e.printStackTrace();
			tx.rollback();
		}finally{
			HibernateUtil.closeSession();
		}
		//user:游离状态
		System.out.println("姓名："+user.getId());
		System.out.println("姓名："+user.getName());
		user.setName("朝伟");
		try {
			session = HibernateUtil.getSession();
			tx = session.beginTransaction();
			//持久状态
			session.update(user);
			tx.commit();
		} catch (Exception e) {
			e.printStackTrace();
			tx.rollback();
		}finally{
			HibernateUtil.closeSession();
		}
	}
	
	@Test
	public void testLoad(){
		Session session=null;
		Transaction tx=null;
		User user=null;
		try {
			session = HibernateUtil.getSession();
			tx = session.beginTransaction();
			//持久状态
			//load方法 相当于 之前的getById
			//如果load查询的数据不存在，那么 抛出异常
			//load不会立即查询数据，当使用的时候再查找数据
			user = (User)session.load(User.class,1) ;
			//System.out.println(user);
			System.out.println("id："+user.getId());
			System.out.println("姓名："+user.getName());
			tx.commit();
		} catch (Exception e) {
			e.printStackTrace();
			tx.rollback();
		}finally{
			HibernateUtil.closeSession();
		}
	}
	
	@Test
	public void testGet(){
		Session session=null;
		Transaction tx=null;
		User user=null;
		try {
			session = HibernateUtil.getSession();
			tx = session.beginTransaction();
			//持久状态
			//get方法 相当于 之前的getById
			//如果get查询的数据不存在，那么返回null
			//get方法会立即查询数据(session--数据库)
			user = (User)session.get(User.class, 1) ;
			System.out.println(user);
			user.setName("张三");
			//System.out.println("姓名："+user.getName());
			tx.commit();
		} catch (Exception e) {
			e.printStackTrace();
			tx.rollback();
		}finally{
			//关闭session
			HibernateUtil.closeSession();
		}
		//游离状态
		user.setName("siggy");
		System.out.println("============");
		try {
			session = HibernateUtil.getSession();
			tx = session.beginTransaction();
			//持久
			session.update(user);
			tx.commit();
		} catch (Exception e) {
			e.printStackTrace();
			tx.rollback();
		}finally{
			//关闭session
			HibernateUtil.closeSession();
		}
	}
	
	@Test
	public void testGet1(){
		Session session=null;
		Transaction tx=null;
		User user=null;
		try {
			session = HibernateUtil.getSession();
			tx = session.beginTransaction();
			//持久状态
			//get方法 相当于 之前的getById
			//如果get查询的数据不存在，那么返回null
			//get方法会立即查询数据(session--数据库)
			user = (User)session.get(User.class, 2) ;
			session.delete(user);
			//瞬时状态
			user.setName("王五");
			tx.commit();
		} catch (Exception e) {
			e.printStackTrace();
			tx.rollback();
		}finally{
			//关闭session
			HibernateUtil.closeSession();
		}
		//瞬时状态
		
	}
	
	@Test
	public void testUpdate(){
		Session session=null;
		Transaction tx=null;
		User user=null;
		try {
			session = HibernateUtil.getSession();
			tx = session.beginTransaction();
			//手动创建对象 可以被更新，需要指定id
			//当指定id不存在时 会抛异常
			user = new User();
			user.setId(10);
			user.setName("paul");
			session.update(user);
			tx.commit();
		} catch (Exception e) {
			e.printStackTrace();
			tx.rollback();
		}finally{
			//关闭session
			HibernateUtil.closeSession();
		}
		//瞬时状态
		
	}
	
	@Test
	public void testUpdate1(){
		Session session=null;
		Transaction tx=null;
		User user=null;
		try {
			session = HibernateUtil.getSession();
			tx = session.beginTransaction();
			//手动创建对象 可以被更新，需要指定id
			//当指定id不存在时 会抛异常
			user = (User)session.get(User.class, 1);
			user.setName("t_bag");
			user.setPwd("3333");
			session.update(user);
			tx.commit();
		} catch (Exception e) {
			e.printStackTrace();
			tx.rollback();
		}finally{
			//关闭session
			HibernateUtil.closeSession();
		}
		//瞬时状态
	}
	
	@Test
	public void testDelete(){
		Session session=null;
		Transaction tx=null;
		User user=null;
		try {
			session = HibernateUtil.getSession();
			tx = session.beginTransaction();
			//手动构建对象 并指定id可以从数据库删除
			//如果指定id不存在 将抛异常
			user = new User();
			user.setId(3);
			session.delete(user);
			tx.commit();
		} catch (Exception e) {
			e.printStackTrace();
			tx.rollback();
		}finally{
			//关闭session
			HibernateUtil.closeSession();
		}
		//瞬时状态
	}
	
	@Test
	public void testDelete1(){
		Session session=null;
		Transaction tx=null;
		User user=null;
		try {
			session = HibernateUtil.getSession();
			tx = session.beginTransaction();
			user = (User)session.get(User.class, 1);
			if(user!=null)
				session.delete(user);
			tx.commit();
		} catch (Exception e) {
			e.printStackTrace();
			tx.rollback();
		}finally{
			//关闭session
			HibernateUtil.closeSession();
		}
		//瞬时状态
		System.out.println(user.getId() + "+" + user.getName());
	}
}