034:coreAPI_Delect,load,get,delete,update,saveOrupdate,clear,flush

@Testpublic void testDelete() {Teacher t = new Teacher();t.setName("t1");t.setTitle("middle");t.setBirthDate(new Date());Session session = sessionFactory.getCurrentSession();session.beginTransaction();session.save(t);System.out.println(t.getId());session.getTransaction().commit();Session session2 = sessionFactory.getCurrentSession();session2.beginTransaction();session2.delete(t);session2.getTransaction().commit();}@Testpublic void testDelete2() {Teacher t = new Teacher();t.setId(2);Session session2 = sessionFactory.getCurrentSession();session2.beginTransaction();session2.delete(t);session2.getTransaction().commit();}

load:从数据库里取一个记录，取到内存里，把这条记录转换成对应的对象

Teacher t = (Teacher) session.load(Teacher.class, 1);

意为：
从数据库里拿到了ID为1的那条记录了，它会自动转换成一个对象t,同时会把这个对象转换成Persistent的状态【即缓存里有数据库里也有】
get与load的区别：

1、不存在对应记录的表现不一样

2、load返回的是代理对象，等到真正用到以象的内容时才发出sql语句。

3、get直接从数据库加载，不会延迟。

@Testpublic void testLoad() {Session session = sessionFactory.getCurrentSession();session.beginTransaction();Teacher t = (Teacher) session.load(Teacher.class, 1);session.getTransaction().commit();System.out.println(t.getClass());// System.out.println(t.getName());}@Testpublic void testGet() {Session session = sessionFactory.getCurrentSession();session.beginTransaction();Teacher t = (Teacher) session.get(Teacher.class, 1);session.getTransaction().commit();System.out.println(t.getClass());// System.out.println(t.getName());}

 

package com.bjsxt.hibernate;import java.util.Date;import org.hibernate.Query;import org.hibernate.Session;import org.hibernate.SessionFactory;import org.hibernate.cfg.AnnotationConfiguration;import org.hibernate.tool.hbm2ddl.SchemaExport;import org.junit.AfterClass;import org.junit.BeforeClass;import org.junit.Test;public class HibernateCoreAPITest {private static SessionFactory sessionFactory;@BeforeClasspublic static void beforeClass() {sessionFactory = new AnnotationConfiguration().configure().buildSessionFactory();}@AfterClasspublic static void afterClass() {sessionFactory.close();}@Testpublic void testTeacherSave() {Teacher t = new Teacher();t.setName("t1");t.setTitle("middle");t.setBirthDate(new Date());// Session session = sessionFactory.openSession();Session session = sessionFactory.getCurrentSession();session.beginTransaction();session.save(t);Session session2 = sessionFactory.getCurrentSession();System.out.println(session == session2);session.getTransaction().commit();Session session3 = sessionFactory.getCurrentSession();System.out.println(session == session3);}@Testpublic void testSaveWith3State() {Teacher t = new Teacher();t.setName("t1");t.setTitle("middle");t.setBirthDate(new Date());Session session = sessionFactory.getCurrentSession();session.beginTransaction();session.save(t);System.out.println(t.getId());session.getTransaction().commit();System.out.println(t.getId());}@Testpublic void testDelete() {Teacher t = new Teacher();t.setName("t1");t.setTitle("middle");t.setBirthDate(new Date());Session session = sessionFactory.getCurrentSession();session.beginTransaction();session.save(t);System.out.println(t.getId());session.getTransaction().commit();Session session2 = sessionFactory.getCurrentSession();session2.beginTransaction();session2.delete(t);session2.getTransaction().commit();}@Testpublic void testDelete2() {Teacher t = new Teacher();t.setId(2);Session session2 = sessionFactory.getCurrentSession();session2.beginTransaction();session2.delete(t);session2.getTransaction().commit();}@Testpublic void testLoad() {Session session = sessionFactory.getCurrentSession();session.beginTransaction();Teacher t = (Teacher) session.load(Teacher.class, 1);session.getTransaction().commit();System.out.println(t.getClass());// System.out.println(t.getName());}@Testpublic void testGet() {Session session = sessionFactory.getCurrentSession();session.beginTransaction();Teacher t = (Teacher) session.get(Teacher.class, 1);session.getTransaction().commit();System.out.println(t.getClass());// System.out.println(t.getName());}@Testpublic void testUpdate1() {Session session = sessionFactory.getCurrentSession();session.beginTransaction();Teacher t = (Teacher) session.get(Teacher.class, 1);session.getTransaction().commit();t.setName("zhanglaoshi");Session session2 = sessionFactory.getCurrentSession();session2.beginTransaction();session2.update(t);session2.getTransaction().commit();}@Testpublic void testUpdate2() {Teacher t = new Teacher();t.setName("zhanglaoshi");Session session2 = sessionFactory.getCurrentSession();session2.beginTransaction();session2.update(t);session2.getTransaction().commit();}@Testpublic void testUpdate3() {Teacher t = new Teacher();t.setId(1);t.setName("zhanglaoshi");Session session2 = sessionFactory.getCurrentSession();session2.beginTransaction();session2.update(t);session2.getTransaction().commit();}@Testpublic void testUpdate4() {Session session = sessionFactory.getCurrentSession();session.beginTransaction();Teacher t = (Teacher) session.get(Teacher.class, 1);t.setName("zhangsan2");session.getTransaction().commit();}@Testpublic void testUpdate5() {Session session = sessionFactory.getCurrentSession();session.beginTransaction();Student s = (Student) session.get(Student.class, 1);s.setName("zhangsan5");session.getTransaction().commit();s.setName("z4");Session session2 = sessionFactory.getCurrentSession();session2.beginTransaction();session2.update(s);session2.getTransaction().commit();}@Testpublic void testUpdate6() {Session session = sessionFactory.getCurrentSession();session.beginTransaction();Student s = (Student) session.get(Student.class, 1);s.setName("zhangsan6");session.getTransaction().commit();s.setName("z4");Session session2 = sessionFactory.getCurrentSession();session2.beginTransaction();session2.merge(s);session2.getTransaction().commit();}@Testpublic void testUpdate7() {Session session = sessionFactory.getCurrentSession();session.beginTransaction();Query q = session.createQuery("update Student s set s.name='z5' where s.id = 1");q.executeUpdate();session.getTransaction().commit();}@Testpublic void testSaveOrUpdate() {Teacher t = new Teacher();t.setName("t1");t.setTitle("middle");t.setBirthDate(new Date());Session session = sessionFactory.getCurrentSession();session.beginTransaction();session.saveOrUpdate(t);session.getTransaction().commit();t.setName("t2");Session session2 = sessionFactory.getCurrentSession();session2.beginTransaction();session2.saveOrUpdate(t);session2.getTransaction().commit();}@Testpublic void testClear() {Session session = sessionFactory.getCurrentSession();session.beginTransaction();Teacher t = (Teacher) session.load(Teacher.class, 1);System.out.println(t.getName());session.clear();Teacher t2 = (Teacher) session.load(Teacher.class, 1);System.out.println(t2.getName());session.getTransaction().commit();}@Testpublic void testFlush() {Session session = sessionFactory.getCurrentSession();session.beginTransaction();Teacher t = (Teacher) session.load(Teacher.class, 1);t.setName("tttt");session.clear();t.setName("ttttt");session.getTransaction().commit();}<pre class="java" name="code">/*@Testpublic void testSchemaExport() {new SchemaExport(new AnnotationConfiguration().configure()).create(false, true);}*/

public static void main(String[] args) {beforeClass();}}

如果不在hibernate.cfg.xml中不加：

  <!-- Drop and re-create the database schema on startup -->
        <!-- 要不要hibernate 自动生成建表语句 -->
         <property name="hbm2ddl.auto">create</property>

则要加上上面的：

/*@Testpublic void testSchemaExport() {new SchemaExport(new AnnotationConfiguration().configure()).create(false, true);}*/

让它自动建表。