hibernate简单增删改查

时间 2019-12-06

原文原文链接

一dao层java

package cn.itcast.b_dao;

import java.util.List;

import org.hibernate.Query;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;

import cn.itcast.a_helloword.User;

public class UserDao {
    private static SessionFactory sessionFactory;

    static {
       //读取配置文件并生成Session工厂对象
        Configuration cfg=new Configuration();
        cfg.configure("hibernate.cfg.xml");
        sessionFactory=cfg.buildSessionFactory();
    }

    /**
     * 保存用户
     * @param user
     */
    public void save(User user){
        Session session=sessionFactory.openSession();
        Transaction tx = null;
        try {
            tx=session.beginTransaction();
            session.save(user);//更新
            tx.commit();
        } catch (RuntimeException e) {
            tx.rollback();
            throw e;
        } finally{
            session.close();
        }
    }

    /**
     * 更新用户
     * @param user
     */
    public void update(User user){
        Session session=sessionFactory.openSession();
        Transaction tx = null;
        try {
            tx=session.beginTransaction();
            session.update(user);//保存
            tx.commit();
        } catch (RuntimeException e) {
            tx.rollback();
            throw e;
        } finally{
            session.close();
        }
    }

    /**
     *获取指定id的对象
     * @param id
     * @return
     */
    public User getById(int id){
        Session session=sessionFactory.openSession();
        Transaction tx=null;
        try {
            tx=session.beginTransaction();
            User user = (User)session.get(User.class, id);//获取
            tx.commit();
            return user;
        } catch (RuntimeException e) {
            tx.rollback();
            throw e;
        }finally{
            session.close();
        }
    }

    /**
     * 删除指定id的用户
     *
     * @param id
     */
    public void delete(int id) {
        Session session = sessionFactory.openSession();
        Transaction tx = null;
        try {
            tx = session.beginTransaction();
            // -------------------------------------
            Object user = session.get(User.class, id); // 先从数据库获取对象
            session.delete(user); // 删除的是实体对象
            // -------------------------------------
            tx.commit();
        } catch (RuntimeException e) {
            tx.rollback();
            throw e;
        } finally {
            session.close();
        }
    }

    /**
     * 查询全部
     * @return
     */
   public List<User> findAll(){
       Session session = sessionFactory.openSession();
       Transaction tx = null;
       try {
        tx=session.beginTransaction();
        List<User> list = session.createQuery("FROM User").list();//使用H QL查询
        tx.commit();
        return list;
    } catch (RuntimeException e) {
        tx.rollback();
        throw e;
    } finally{
        session.close();
    }
   }

   /**
    *
    * @param firstResult
    *        开始获取的记录的索引
    * @param maxResult
    *        最多获取多少条数据
    * @return 总记录数+一段数据
    */
   public QueryResult<User> findAll(int firstResult,int maxResult){
       Session session = sessionFactory.openSession();
       Transaction tx = null;
       try {
        tx=session.beginTransaction();

        //1.查询总记录数
        Long count = (Long) session.createQuery(
                     "SELECT COUNT(*) FROM User")
                     .uniqueResult(); //执行查询
        //2. 查询一段数据
        Query query = session.createQuery("FROM User");
        query.setFirstResult(firstResult);
        query.setMaxResults(maxResult);
        List<User> list = query.list();
        tx.commit();
        return new QueryResult<User>(list, count);
    } catch (RuntimeException e) {
        tx.rollback();
        throw e;
    }finally{
        session.close();
    }
   }
}数据库

二分页对象session

package cn.itcast.b_dao;

import java.util.List;

public class QueryResult<T> {
    private List<T> list; //一段数据
    private Long count;  //总记录数

    public QueryResult(List<T> list, Long count) {
        super();
        this.list = list;
        this.count = count;
    }

    public List<T> getList() {
        return list;
    }
    public void setList(List<T> list) {
        this.list = list;
    }
    public Long getCount() {
        return count;
    }
    public void setCount(Long count) {
        this.count = count;
    }
}测试

三测试ui

package cn.itcast.b_dao;

import static org.junit.Assert.*;

import java.util.List;

import org.junit.Test;

import cn.itcast.a_helloword.User;

public class UserDaoTest {

    private UserDao userDao=new UserDao();

    @Test
    public void testSave() {
        //准备对象
        User user=new User();
        user.setName("张三");

        //保存到数据库
        userDao.save(user);
    }

    @Test
    public void testSave_25() {
        for(int i = 1; i <= 25; i++){
            User user=new User();
            user.setName("张三-"+i);
            userDao.save(user);
        }
    }

    @Test
    public void testGetById() {
        User user=userDao.getById(1);
        System.out.println(user);
    }

    @Test
    public void testUpdate() {
        //修改已有的对象
        User user=userDao.getById(1);
        user.setName("李四");
        //跟新到数据库
        userDao.update(user);
    }

    @Test
    public void testDelete() {
        userDao.delete(1);
    }

    @Test
    public void testFindAll() {
        //查询
        List<User> list = userDao.findAll();

        //显示
        for(User user : list){
            System.out.println(user);
        }
    }

    @Test
    public void testFindAllIntInt() {
        //分页的查询
        QueryResult<User> qr= userDao.findAll(0,10000);

        //显示
        System.out.println("总记录的数量："+qr.getCount());

        for(User user : qr.getList()){
            System.out.println(user);
        }
    }

}this