hibernate学习笔记2--简单的使用

最新推荐文章于 2020-07-07 14:35:37 发布

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#hibernate学习笔记2--简单的使用

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本文介绍了一个简单的Hibernate配置文件，并展示了如何使用注解来定义实体映射。此外，还提供了基本的增删改查(CRUD)操作示例。

首先记录一下基于注解的hibernate.cfg.xml文件的内容吧：

<?xml version='1.0' encoding='utf-8'?>
<!DOCTYPE hibernate-configuration PUBLIC
        "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
        "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
    <session-factory>
        <property name="connection.driver_class">com.mysql.jdbc.Driver</property>
        <property name="connection.url">jdbc:mysql://127.0.0.1:3306/item</property>
        <property name="connection.username">root</property>
        <property name="connection.password">123456</property>

        <property name="dialect">org.hibernate.dialect.MySQLDialect</property>

        <property name="show_sql">true</property>
        <property name="format_sql">true</property>
        <mapping  class="cn.bdx.po.User"/>
    </session-factory>
</hibernate-configuration>

这是一个可以说是简单地不能再简单的配置文件了，具体内容在这里先不详细记录了。

pojo类：

package cn.bdx.po;

import javax.persistence.*;
import java.io.Serializable;

/**
 * Created by Administrator on 2016/5/23.
 */
@Entity
@Table(name="t_user")
public class User{

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private int id;
    private String name;
    private int age;

    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 int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", age=" + age +
                '}';
    }
}

HibernateUtils类的代码：

package cn.bdx.utils;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;

/**
 * Created by Administrator on 2016/5/23.
 */
public class HibernateUtils {

    private static SessionFactory sessionFactory;

    static {
        Configuration configuration = new Configuration().configure();
        ServiceRegistry serviceRegistry = new StandardServiceRegistryBuilder().applySettings(configuration.getProperties()).build();
        sessionFactory = configuration.buildSessionFactory(serviceRegistry);
    }

    public static SessionFactory getSessionFactory() {
        return sessionFactory;
    }

    public static Session getSession() throws Exception {
        if (sessionFactory == null) {
            throw new Exception("sessionFactory is empty");
        }
        return sessionFactory.openSession();
    }

}

这里面的内容在上一篇中讲解了。

最后就是获取到Session对象进行持久化的操作了，下面是写的一些简单的单表操作的方法，以供以后借鉴吧：

package cn.bdx.dao;

import cn.bdx.po.User;
import cn.bdx.utils.HibernateUtils;
import org.hibernate.Query;
import org.hibernate.Session;
import org.hibernate.Transaction;
import org.hibernate.transform.Transformers;

import java.util.List;

/**
 * Created by Administrator on 2016/5/23.
 */
public class UserDao {

    public void add(User user) throws Exception {
        Session session = HibernateUtils.getSession();
        Transaction transaction = session.getTransaction();
        try {
            transaction.begin();
            session.persist(user);
            transaction.commit();
        } catch (Exception e) {
            transaction.rollback();
            e.printStackTrace();
        }
    }

    public void update(User user) throws  Exception{
        Session session = HibernateUtils.getSession();
        Transaction transaction = session.getTransaction();
        try{
            transaction.begin();
            session.update(user);
            transaction.commit();
        }catch (Exception e) {
            transaction.rollback();
        }
    }
    public void query() throws Exception {
        Session session = HibernateUtils.getSession();
        Transaction transaction = session.getTransaction();
        try {
            transaction.begin();
            User user = (User) session.get(User.class, 1);
            System.out.print(user);
            transaction.commit();
        } catch (Exception e) {
            transaction.rollback();
            e.printStackTrace();
        }
    }

    public void queryByHql() throws Exception {
        Session session = HibernateUtils.getSession();
        Transaction transaction = session.getTransaction();
        try {
            transaction.begin();
            org.hibernate.Query query = session.createQuery("from User");
            List<User> userList = query.list();
            for(User user:userList) {
                System.out.print(user.getName());
            }
            transaction.commit();
        } catch (Exception e) {
            transaction.rollback();
        }
    }

    public void queryBySql() throws Exception {
        Session session = HibernateUtils.getSession();
        Transaction transaction = session.getTransaction();
        try{
            transaction.begin();
            Query query= session.createSQLQuery("SELECT age,name FROM t_user").setResultTransformer(Transformers.aliasToBean(User.class));
            List list = query.list();
            System.out.println(list);
            transaction.commit();
        }catch (Exception e) {
            transaction.rollback();
        }
    }

    public void delete(User user) throws Exception{
        Session session = HibernateUtils.getSession();
        Transaction transaction = session.getTransaction();
        try{
            transaction.begin();
            session.delete(user);
            transaction.commit();
        }catch (Exception e) {
            transaction.rollback();
        }
    }
 }