Hibernate中对象的状态

一、对象状态介绍

 1.瞬时状态：自己new出来的对象就是瞬时状态。在数据库表中没有记录和对象相对应。

 2.持久状态：调用save方法后，数据库表中有记录和该对象对应，并被session管理。

 3.脱管状态：数据库中有记录和该对象对应，但是对象不被session管理。

二、用代码表示

package com.hbsi.test;

 

import java.util.Date;

 

import org.hibernate.HibernateException;

import org.hibernate.Session;

import org.hibernate.Transaction;

 

import com.hbsi.Hibernate.utils.HibernateUtil;

import com.hbsi.domain.User;

 

public class TestHibernate {

 

       public static voidmain(String[] args) {

 

              User user = newUser();

              user.setName("Jerry");   //此时为瞬时状态

              user.setBirthday(newDate());

             

              //增

              addUser(user);

             

             

              //查

              user =getUser(1);

              System.out.println(user.getId()+"\t"+user.getName()+"\t\t"+user.getBirthday());

//此时为托管状态

 

       }

 

       public static voidaddUser(User user) {

              Session session =null;

              // 开启事物

              Transaction tx =null;

              try {

                     session =HibernateUtil.getSession();

                     tx =session.beginTransaction();

 

                     session.save(user);  //此时为持久状态

                     tx.commit();

              } catch(HibernateException ex) {

                     if (tx !=null) {

                            tx.rollback();

                     }

                     throw ex;

              } finally {

                     if(session != null) {

                            session.close();

                     }

              }

 

       }

 

       public static voidaddUser1(User user) {

              Session session =null;

              // 开启事物

              Transaction tx =null;

              try {

                     session =HibernateUtil.getSession();

                     tx =session.beginTransaction();

 

                     session.save(user);

                     tx.commit();

              } finally {

                     if(session != null) {

                            session.close();

                     }

              }

 

       }

 

       public static UsergetUser(int id) {

              Session session =null;

              try {

                     session =HibernateUtil.getSession();

                    

                     /*懒加载：得到的是代理对象，代理对象不为null,但它也没有

                      * 访问数据库。在第一次使用代理对象时，获取Session，访问数据库。

                      * */

                     //Useruser = (User) session.load(User.class, id);

                     //System.out.println(user.getId()+"\t"+user.getName()+"\t\t"+user.getBirthday());

                    

                     User user= (User) session.get(User.class, id);

 

                     returnuser;

              } finally {

                     if(session != null) {

                            session.close();

                     }

              }

 

       }

 

}