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

@Test
public 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();
}

@Test
public 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。

@Test
public 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());
}

@Test
public 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;

@BeforeClass
public static void beforeClass() {
sessionFactory = new AnnotationConfiguration().configure().buildSessionFactory();
}

@AfterClass
public static void afterClass() {
sessionFactory.close();
}

@Test
public 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);

}

@Test
public 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());
}

@Test
public 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();
}

@Test
public void testDelete2() {

Teacher t = new Teacher();
t.setId(2);

Session session2 = sessionFactory.getCurrentSession();
session2.beginTransaction();
session2.delete(t);
session2.getTransaction().commit();
}
@Test
public 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());
}

@Test
public 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());
}

@Test
public 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();
}

@Test
public void testUpdate2() {

Teacher t = new Teacher();
t.setName("zhanglaoshi");

Session session2 = sessionFactory.getCurrentSession();
session2.beginTransaction();
session2.update(t);

session2.getTransaction().commit();
}

@Test
public void testUpdate3() {

Teacher t = new Teacher();
t.setId(1);
t.setName("zhanglaoshi");

Session session2 = sessionFactory.getCurrentSession();
session2.beginTransaction();
session2.update(t);

session2.getTransaction().commit();
}

@Test
public void testUpdate4() {

Session session = sessionFactory.getCurrentSession();
session.beginTransaction();
Teacher t = (Teacher) session.get(Teacher.class, 1);
t.setName("zhangsan2");
session.getTransaction().commit();
}

@Test
public 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();
}

@Test
public 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();
}

@Test
public 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();

}

@Test
public 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();

}

@Test
public 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();

}

@Test
public 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">/*
@Test
public 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：

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

让它自动建表。