【Hibernate QBC】

HibernateQBC

public class HibernateQBC {

    //演示离线查询
    @Test
    public void testSelect6() {
        SessionFactory sessionFactory = null;
        Session session = null;
        Transaction tx = null;
        try {
            sessionFactory = HibernateUtils.getSessionFactory();
            session = sessionFactory.openSession();
            tx = session.beginTransaction();

            //1 创建对象
//            Criteria criteria = session.createCriteria(Customer.class);
            DetachedCriteria detachedCriteria = DetachedCriteria.forClass(Customer.class);

            //2 最终执行时候才需要到session
            Criteria criteria = detachedCriteria.getExecutableCriteria(session);

            List<Customer> list = criteria.list();

            for (Customer customer : list) {
                System.out.println(customer.getCid() + "::" + customer.getCustName());
            }

            tx.commit();
        } catch (Exception e) {
            e.printStackTrace();
            tx.rollback();
        } finally {
            session.close();
            sessionFactory.close();
        }
    }

    //演示统计查询
    @Test
    public void testSelect5() {
        SessionFactory sessionFactory = null;
        Session session = null;
        Transaction tx = null;
        try {
            sessionFactory = HibernateUtils.getSessionFactory();
            session = sessionFactory.openSession();
            tx = session.beginTransaction();

            //1 创建对象
            Criteria criteria = session.createCriteria(Customer.class);

            //2 设置操作
            criteria.setProjection(Projections.rowCount());

            //3 调用方法得到结果
            Object obj = criteria.uniqueResult();

            Long lobj = (Long) obj;
            int count = lobj.intValue();

            System.out.println(count);

            tx.commit();
        } catch (Exception e) {
            e.printStackTrace();
            tx.rollback();
        } finally {
            session.close();
            sessionFactory.close();
        }
    }

    //演示分页查询
    @Test
    public void testSelect4() {
        SessionFactory sessionFactory = null;
        Session session = null;
        Transaction tx = null;
        try {
            sessionFactory = HibernateUtils.getSessionFactory();
            session = sessionFactory.openSession();
            tx = session.beginTransaction();

            //1 创建对象
            Criteria criteria = session.createCriteria(Customer.class);

            //2 设置分页数据
            //2.1 设置开始位置
            criteria.setFirstResult(0);
            //2.2 每页显示记录数
            criteria.setMaxResults(3);

            //3 调用方法得到结果
            List<Customer> list = criteria.list();

            for (Customer customer : list) {
                System.out.println(customer.getCid() + "::" + customer.getCustName());
            }
            tx.commit();
        } catch (Exception e) {
            e.printStackTrace();
            tx.rollback();
        } finally {
            session.close();
            sessionFactory.close();
        }
    }

    //演示排序查询
    @Test
    public void testSelect3() {
        SessionFactory sessionFactory = null;
        Session session = null;
        Transaction tx = null;
        try {
            sessionFactory = HibernateUtils.getSessionFactory();
            session = sessionFactory.openSession();
            tx = session.beginTransaction();

            //1 创建对象
            Criteria criteria = session.createCriteria(Customer.class);

            //2 设置对哪个属性进行排序，设置排序规则
            criteria.addOrder(Order.desc("cid"));

            //3 调用方法得到结果
            List<Customer> list = criteria.list();

            for (Customer customer : list) {
                System.out.println(customer.getCid() + "::" + customer.getCustName());
            }
            tx.commit();
        } catch (Exception e) {
            e.printStackTrace();
            tx.rollback();
        } finally {
            session.close();
            sessionFactory.close();
        }
    }

    //演示条件查询
    @Test
    public void testSelect2() {
        SessionFactory sessionFactory = null;
        Session session = null;
        Transaction tx = null;
        try {
            sessionFactory = HibernateUtils.getSessionFactory();
            session = sessionFactory.openSession();
            tx = session.beginTransaction();

            //1 创建对象
            Criteria criteria = session.createCriteria(Customer.class);

            //2 使用Criteria对象里面的方法设置条件值
            // 首先使用add方法，表示设置条件值
            // 在add方法里面使用类的方法实现条件设置
            // 类似于 cid=?
//            criteria.add(Restrictions.eq("cid", 1));
//            criteria.add(Restrictions.eq("custName", "百度"));

            criteria.add(Restrictions.like("custName", "%百%"));

            //3 调用方法得到结果
            List<Customer> list = criteria.list();

            for (Customer customer : list) {
                System.out.println(customer.getCid() + "::" + customer.getCustName());
            }
            tx.commit();
        } catch (Exception e) {
            e.printStackTrace();
            tx.rollback();
        } finally {
            session.close();
            sessionFactory.close();
        }
    }

    //演示查询所有
    @Test
    public void testSelect1() {
        SessionFactory sessionFactory = null;
        Session session = null;
        Transaction tx = null;
        try {
            sessionFactory = HibernateUtils.getSessionFactory();
            session = sessionFactory.openSession();
            tx = session.beginTransaction();

            //1 创建对象
            Criteria criteria = session.createCriteria(Customer.class);
            //2 调用方法得到结果
            List<Customer> list = criteria.list();

            for (Customer customer : list) {
                System.out.println(customer.getCid() + "::" + customer.getCustName());
            }
            tx.commit();
        } catch (Exception e) {
            e.printStackTrace();
            tx.rollback();
        } finally {
            session.close();
            sessionFactory.close();
        }
    }
}