java 状态对象

 package cn.itcast.hibernate.sh.state;

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

 import cn.itcast.hibernate.sh.domain.Person;
 import cn.itcast.hibernate.sh.utils.HiberanteUtils;

 public class StateTest extends HiberanteUtils{
     /**
      * session.save方法把一个临时状态的对象转化成持久化状态的对象
      */
     @Test
     public void testSavePerson(){
         Session session = sessionFactory.openSession();
         Transaction transaction = session.beginTransaction();
         Person person = new Person();
         person.setPname("afds");
         person.setPsex("af");
         session.save(person);
         transaction.commit();
         session.close();
     }

     /**
      * session.update方法可以把一个对象的状态变成持久化状态
      */
     @Test
     public void testUpdate(){
         Session session = sessionFactory.openSession();
         Transaction transaction = session.beginTransaction();
         Person person2 = new Person();//临时状态
         person2.setPid(1L);//临时状态
         session.update(person2);//持久化状态
         transaction.commit();
         session.close();
     }

     /**
      * 当session.get方法得到一个对象的时候，是不需要再执行 update语句，因为已经是持久化状态
      * 当一个对象是一个持久化对象的时候,当进行提交的时候,hibernate内部会让该对象和快照进行对比,如果一样,则不发出update语句
      * 如果不一样，则发出update语句
      */
     @Test
     public void testGet(){
         Session session = sessionFactory.openSession();
         //Transaction transaction = session.beginTransaction();
         Person person = (Person)session.get(Person.class, 1L);//持久化
         person.setPname("tt");
         //session.update(person);
         //transaction.commit();
         session.close();
     }

     /**
      * session.clear方法把所有的对象从session中清空
      */
     @Test
     public void testClear(){
         Session session = sessionFactory.openSession();
         Transaction transaction = session.beginTransaction();
         Person person = (Person)session.get(Person.class, 1L);
         person.setPname("asd");
         session.clear();//把session中所有的对象清空
         session.update(person);//把对象从脱管状态转化成持久化状态
         transaction.commit();
         session.close();
     }

     /**
      * session.evict把一个对象从session中清空
      */
     @Test
     public void testEvict(){
         Session session = sessionFactory.openSession();
         Transaction transaction = session.beginTransaction();
         Person person = (Person)session.get(Person.class, 1L);
         person.setPname("asdsss");
         session.evict(person);//脱管状态
         session.update(person);//把对象的状态转化成持久化状态
         transaction.commit();
         session.close();
     }

     /**
      * 一个对象是否是持久化对象是针对某一个session而言的
      */
     @Test
     public void testSession(){
         Session session = sessionFactory.openSession();
         Transaction transaction = session.beginTransaction();
         Person person = (Person)session.get(Person.class, 1L);
         person.setPname("asfd");
         transaction.commit();
         session.close();
         session =  sessionFactory.openSession();
         transaction =  session.beginTransaction();
         person.setPname("aaaaaaa");//person对象对于94的session来说是一个临时状态的对象
         //session.update(person);
         transaction.commit();
         session.close();
     }

     /**
      * 当执行transaction.commit的时候，hibernate内部会检查session
      *    1、如果一个对象为临时状态的对象，则session不会管
      *    2、如果一个对象是持久化状态的对象，如果有ID值，并且和数据库对应，那么先把该对象与快照进行对比，如果一致，则什么都不做，如果不一致，则发出update语句
      *    3、如果一个对象是持久化状态的对象，如果没有ID值，则会发出save语句
      */
     @Test
     public void testMuplyOption(){
         Session session = sessionFactory.openSession();
         Transaction transaction = session.beginTransaction();
         Person person = new Person();
         person.setPname("rrr");
         person.setPsex("asdfasdf");

         Person person3 = new Person();
         person3.setPname("rrr");
         person3.setPsex("asdfasdf");

         session.save(person);
         Person person2 = (Person)session.get(Person.class, 1L);
         person2.setPname("afds45");
         transaction.commit();
         session.close();
     }

     @Test
     public void testMutiplyOption2(){
         Session session = sessionFactory.openSession();
         Transaction transaction = session.beginTransaction();
         Person person = new Person();
         person.setPname("asdfads");
         person.setPsex("er");
         session.save(person);
         transaction.commit();
         session.evict(person);
         session.close();

         session = sessionFactory.openSession();
         transaction = session.beginTransaction();
         session.update(person);
         session.clear();
         transaction.commit();
         session.close();
     }
 }