Hibernate文件配置

ORM : 对象关系映射

映射需要通过XML的配置文件来完成，这个配置文件尽量统一（xxx.hbm.xml） Hibernate核心的配置：必须的配置、可选的配置、映射文件的引入

Configuration的作用：1.加载核心配置文件 2.加载映射文件 SessionFactory：内部维护了Hibernate的连接池和Hibernate的二级缓存，是线程安全的对象，一个项目创建一个对象即可 Session：代表Hibernate和数据库的连接对象，不是线程安全的，所以不能定义成全局的变量 Transaction：Hibernate中管理事务的对象

文件结构

工具类

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

public class HibernateUtils {
    public static final Configuration cfg;
    public static final SessionFactory sf;

    static {
        cfg = new Configuration().configure();
        sf = cfg.buildSessionFactory();
    }

    public static Session openSession() {
        return sf.openSession();
    }
}

对象类

public class Customer {
    private int id;
    private String name;
    private String source;
    private String industry;
    private String level;
    private String phone;
    private String mobile;

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getSource() {
        return source;
    }

    public void setSource(String source) {
        this.source = source;
    }

    public String getIndustry() {
        return industry;
    }

    public void setIndustry(String industry) {
        this.industry = industry;
    }

    public String getLevel() {
        return level;
    }

    public void setLevel(String level) {
        this.level = level;
    }

    public String getPhone() {
        return phone;
    }

    public void setPhone(String phone) {
        this.phone = phone;
    }

    public String getMobile() {
        return mobile;
    }

    public void setMobile(String mobile) {
        this.mobile = mobile;
    }

    @Override
    public String toString() {
        return "Customer{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", source='" + source + '\'' +
                ", industry='" + industry + '\'' +
                ", level='" + level + '\'' +
                ", phone='" + phone + '\'' +
                ", mobile='" + mobile + '\'' +
                '}';
    }
}

映射配置文件

总配置类

    
        
        com.mysql.jdbc.Driver
        jdbc:mysql://localhost:3306/spring_database?characterEncoding=utf8
        
        root
        1234
        
        org.hibernate.dialect.MySQLDialect

        
        
        true
        
        true
        
        update

        
        
    

测试类

import com.jinke.hibernate.utils.HibernateUtils;
import org.hibernate.Session;
import org.hibernate.Transaction;
import org.hibernate.query.NativeQuery;
import org.hibernate.query.Query;
import org.junit.Test;

import java.util.Arrays;
import java.util.List;

public class HibernateDemo1 {

    @Test
    public void demo() {
       /* //1.加载hibernate核心配置文件
        Configuration configuration = new Configuration().configure();
        //2.创建一个sessionfactory对象：类似于jdbc中连接池
        SessionFactory sessionFactory = configuration.buildSessionFactory();
        //3.通过sessionFactory获取到session对象：类似于jdbc中connection
        Session session = sessionFactory.openSession();*/

        Session session = HibernateUtils.openSession();
        //4.手动开启事务
        Transaction transaction = session.beginTransaction();
        //5.编写代码

        Customer customer = new Customer();
        customer.setName("王东");
        //保存
        session.save(customer);


        //6.事务提交
        transaction.commit();
        //7.资源释放
        session.close();
        /*sessionFactory.close();*/
    }

    /**
     * get方法：（一般用这种）
     * 采用立即加载，执行到这行代码的时候，马上发送SQL语句去查询
     * 查询后返回的是真是对象本身
     * 查询一个找不到的对象会返回null
     * 

     * load方法：
     * 采用延迟加载（懒加载），执行到这行代码的时候，不会发送SQL语句，当真正使用项目的时候才会发送SQL语句
     * 查询后返回的是代理对象
     * 查询一个找不到的对象会抛出一个异常
     */
    @Test
    //查询
    public void demo2() {
        Session session = HibernateUtils.openSession();
        Transaction tx = session.beginTransaction();
        //使用get方法
        Customer customer = session.get(Customer.class, 1);
        System.out.println(customer);

        //使用load方法
        /*Customer load = session.load(Customer.class, 2);
        System.out.println(load);*/

        tx.commit();
        session.close();
    }

    @Test
    //修改
    public void demo3() {
        Session session = HibernateUtils.openSession();
        Transaction tx = session.beginTransaction();

        //直接创建对象，进行修改
        /*Customer customer = new Customer();
        customer.setId(1);
        customer.setName("李达");
        session.update(customer);*/
        //先查询，再修改（一般用这种）
        Customer customer = session.get(Customer.class, 1);
        customer.setName("张三");
        session.update(customer);

        tx.commit();
        session.close();
    }

    @Test
    //删除
    public void demo4() {
        Session session = HibernateUtils.openSession();
        Transaction tx = session.beginTransaction();

        //直接创建对象，进行删除
        /*Customer customer = new Customer();
        customer.setId(1);
        session.delete(customer);*/
        //先查询，再删除(一般用这种)  级联删除
        Customer customer = session.get(Customer.class, 1);
        session.delete(customer);

        tx.commit();
        session.close();
    }

    @Test
    //保存或更新
    public void demo5() {
        Session session = HibernateUtils.openSession();
        Transaction tx = session.beginTransaction();

        Customer customer = new Customer();
        /*customer.setName("李飞");
        session.saveOrUpdate(customer);*/

        customer.setId(3);
        customer.setName("如花");
        session.saveOrUpdate(customer);

        tx.commit();
        session.close();
    }

    @Test
    //查询所有
    public void demo6() {
        Session session = HibernateUtils.openSession();
        Transaction tx = session.beginTransaction();
        //接收HQL：hibernate query language 面向对象的查询语言
        Query query = session.createQuery("from Customer");
        List list = query.list();
        for (Customer customer : list) {
            System.out.println(customer);
        }

        //接收sql：
        NativeQuery sqlQuery = session.createSQLQuery("select * from customer");
        List sqlList = sqlQuery.list();
        for (Object[] objects : sqlList) {
            System.out.println(Arrays.toString(objects));
        }

        tx.commit();
        session.close();
    }
}

结果在MySql Workbench里看