JPA+Hibernate3 CRUD(增删改查操作)

JPA与Hibernate3结合的CRUD(增删改查操作)

  
    

   
     package com.archie.test;

import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.Persistence;

import com.archie.model.User;

/**
 * CRUD操作测试
 * @author archie2010
 * since 2011-4-19下午22:13:26
 */
public class CrudTest {
 public static void addUser(){
 EntityManagerFactory factory = Persistence.createEntityManagerFactory("jpaTest");
 // EntityManager相当于Hibernate中session
 EntityManager em = factory.createEntityManager();
 em.getTransaction().begin();
 // 保存(持久化)方法
 em.persist(new User("Tom"));
 em.getTransaction().commit();
 em.close();
 factory.close();
 }
 /**
 * 删除
 */
 public static void deleteUser(){
 EntityManagerFactory factory = Persistence.createEntityManagerFactory("jpaTest");
 EntityManager em = factory.createEntityManager();
 
 em.getTransaction().begin();
 User user = em.find(User.class, 1);
 em.remove(user);
 em.getTransaction().commit();
 
 em.close();
 factory.close();
 }
 //=======================查询
 /**
 * find方法相当于Hibernate中的get方法，
 * getReference方法相当于Hibernate中的load方法，具有延迟加载的作用；
 * 当查找的对象不存在时，find的方法返回null值，
 * 而getReference方法则抛出异常javax.persistence.EntityNotFoundException
 */
 
 /**
 * 查询byFind
 */
 public static void findUserByFind(){
 
 EntityManagerFactory factory = Persistence.createEntityManagerFactory("jpaTest");
 EntityManager em = factory.createEntityManager();
 
 //Find方法相当于Hibernate中的get方法
 User user = em.find(User.class, 1);
 
 System.out.println(user.getUserName());
 
 em.close();
 factory.close();
 }
 /**
 * 查询ByReference
 */
 public static void findUserByReference(){
 EntityManagerFactory factory = Persistence.createEntityManagerFactory("jpaTest");
 EntityManager em = factory.createEntityManager();
 
 //getReference方法相当于Hibername中的load方法，具有延迟加载的功能
 User user = em.getReference(User.class, 1);
 
 System.out.println(user.getUserName());
 
 em.close();
 factory.close();
 }
 /**
 * 更新
 */
 public static void updateUser(){
 EntityManagerFactory factory = Persistence.createEntityManagerFactory("jpaTest");
 EntityManager em = factory.createEntityManager();
 
 em.getTransaction().begin();
 User user = em.find(User.class, 1);
 user.setUserName("tom_new");
 //相当于hibernate将游离状态下的数据更新到数据库中 
 em.getTransaction().commit();
 
 em.close();
 factory.close();
 }
 /**
 * 更新
 * 将游离状态下的数据更新到数据库中 
 */
 public static void updateUserByMerge(){
 EntityManagerFactory factory = Persistence.createEntityManagerFactory("jpaTest");
 EntityManager em = factory.createEntityManager();
 
 em.getTransaction().begin();
 User user = em.find(User.class, 1);
 //把实体管理器中的实体变成游离状态
 em.clear();
 user.setUserName("tom_Merge");
 //把游离状态下的更新同步到数据库中
 em.merge(user);
 em.getTransaction().commit();
 
 em.close();
 factory.close();
 }
 /**
 * main方法测试
 * @param args
 */
 public static void main(String[] args) {
 /*findUserByFind();
 findUserByReference();
 updateUserByMerge();
 deleteUser();
 */
 addUser();
 }
}