Hibernate（3）——实例总结Hibernate对象的状态和ThreadLoacl封闭的session

/**
* UserDao
*
* @author Wang Yishuai.
* @date 2016/2/2 0002.
* @Copyright(c) 2016 Wang Yishuai,USTC,SSE.
*/
public class UserDao {
final Logger LOG = LoggerFactory.getLogger(UserDao.class); private SessionFactory sessionFactory; private UserDao() {
// 通过new一个Configuration实例，然后用该实例去调用configure返回一个配置实例
Configuration configuration = new Configuration().configure();
// 通过 配置实例的buildSessionFactory方法 生成一个 sessionFactory 对象
// buildSessionFactory方法会默认的去寻找配置文件hibernate.cfg.xml并解析xml文件
// 解析完毕生成sessionFactory，负责连接数据库
this.sessionFactory = configuration.buildSessionFactory();
} public static UserDao newInstance() {
return new UserDao();
} public void save(User user) {
// 通过 sessionFactory 获得一个数据库连接 session，可以操作数据库
Session session = sessionFactory.openSession();
// 把操作封装到数据库的事务，则需要开启一个事务
Transaction transaction = session.beginTransaction(); // 一般把对实体类和数据库的操作，放到try-catch-finally块
try {
// 把user对象插入到数据库
session.save(user);
// 提交操作事务
transaction.commit();
LOG.info("transaction.commit(); ok");
} catch (Exception e) {
// 提交事务失败，必须要回滚
transaction.rollback();
// 打印日志
LOG.error("save user error......", e);
} finally {
// 不能丢这一步，要释放资源
session.close();
LOG.info("session.close(); ok");
}
} public void retriveAll() {
Session session = sessionFactory.openSession();
List<User> userList = session.createQuery("from User").list();
session.close(); for (User user : userList) {
LOG.info("username = {}", user.getUsername());
}
} public void delete(User user) {
Session session = sessionFactory.openSession();
Transaction transaction = session.beginTransaction(); user = (User) session.get(user.getClass(), user.getUserId());
session.delete(user);
transaction.commit();
session.close();
} public void update(User user) {
Session session = sessionFactory.openSession();
Transaction transaction = session.beginTransaction();
user = (User) session.get(user.getClass(), user.getUserId());
user.setUsername("dadad");
session.update(user);
transaction.commit();
session.close();
}
}

package test.java; import dashuai.dao.UserDao;
import dashuai.vo.User;
import org.junit.After;
import org.junit.Before;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory; /**
* Test
*
* @author Wang Yishuai.
* @date 2016/3/10 0010.
* @Copyright(c) 2016 Wang Yishuai,USTC,SSE.
*/
public class Test {
private static final Logger LOG = LoggerFactory.getLogger(Test.class); private UserDao userDao; @Before
public void init() {
LOG.info("init");
this.userDao = UserDao.newInstance();
} @After
public void clear() {
LOG.info("clear");
} @org.junit.Test
public void testHibernate1() {
User user = new User();
user.setUsername("niubi");
user.setPassword("1");
// 此时的user对象是瞬时态的 userDao.save(user);
// save到数据库之后，user变为持久态 // 最后在save方法里，最终执行 session.close();使得user变为游离态
user.setUsername("liuxiang");// 数据库中的数据不会变
}
}

public void delete(String account) {
Account acc = (Account) session.createQuery("from Account where account = '" + account + "'").uniqueResult();
Transaction transaction = session.beginTransaction();
acc.setMoney(acc.getMoney() - 100);
transaction.commit();
session.close();
} public void addMoney(String account) {
Account acc = (Account) session.createQuery("from Account where account = '" + account + "'").uniqueResult();
Transaction transaction = session.beginTransaction();
acc.setMoney(acc.getMoney() + 100);
transaction.commit();
session.close();
}

@org.junit.Test
public void testAccount() {
// 账户1
Account account1 = new Account();
account1.setAccount("1");
account1.setAid(1);
account1.setMoney(100.0); // 账户2
Account account2 = new Account();
account2.setAccount("2");
account2.setAid(2);
account2.setMoney(200.0);// accountDao.save(account1);
// accountDao.save(account2);
//
// 把2的账户的钱转100到1账户
// 先增加1账户100元
accountDao.addMoney("1");
// 删除2账户100元
accountDao.delete("2");
}