Hibernate的简单流程

1.首先建立一个java项目或者jsp动态网页项目

将Hibernate4Hibernate4hibernate-release-4.3.11.Finalhibernate-release-4.3.11.Finallib equired文件夹下的10个jar包导入项目中，再将mySQL的驱动包导入并Build Path

2.再将Hibernate的核心配置文件hibernat.cfg.xml导入src文件夹下

并修改配置文件

<?xml version='1.0' encoding='utf-8'?>
<!DOCTYPE hibernate-configuration PUBLIC
        "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
        "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">

<hibernate-configuration>
    <session-factory>
        <!--数据库连接设置 -->
        <property name="connection.driver_class">com.mysql.jdbc.Driver</property>
        <property name="connection.url">jdbc:mysql://localhost:3306/hibernate_demo02</property>
        <property name="connection.username">root</property>
        <property name="connection.password">123456</property>
        
        <!-- 方言 -->
        <property name="dialect">org.hibernate.dialect.MySQL5Dialect</property>
    
        <!-- 控制台显示SQL -->
        <property name="show_sql">true</property>

        <!-- 自动更新表结构 -->
        <property name="hbm2ddl.auto">update</property>
        
        <mapping resource="com/oracle/model/Person.hbm.xml"/>
    </session-factory>
    
</hibernate-configuration>

倒数第三行的mapping标签为映射，映射model层中某一个类所对应的xml配置文件，并且采用地址的形式，resource=“../../../xxx.hbm.xml" （是斜杠不是点）

3.创建HibernateUtil

package com.oracle.util;

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

public class HibernateUtil {
    
    private static final SessionFactory sessionFactory=buildSessionFactory();

    private static SessionFactory buildSessionFactory(){
        Configuration configuration=new Configuration().configure(); //实例化配置文件
        ServiceRegistry serviceRegistry=new StandardServiceRegistryBuilder().applySettings(configuration.getProperties()).build(); //实例化服务登记
        return configuration.buildSessionFactory(serviceRegistry); //获取Session工厂
    }
    
    public static SessionFactory getSessionFactory(){
        return sessionFactory;
    }
}

4.开始创建model层表结构

首先是一个Person类

package com.oracle.model;

import java.util.HashSet;
import java.util.Set;

public class Person {
    private Integer id;
    private String realName;
    private String sex;
    public Person() {
        super();
    }
    public Integer getId() {
        return id;
    }
    public void setId(Integer id) {
        this.id = id;
    }
    public String getRealName() {
        return realName;
    }
    public void setRealName(String realName) {
        this.realName = realName;
    }
    public String getSex() {
        return sex;
    }
    public void setSex(String sex) {
        this.sex = sex;
    }
    public Set<Car> getCars() {
        return cars;
    }
    public void setCars(Set<Car> cars) {
        this.cars = cars;
    }
}

然后创建Person对应的xml配置文件Person.hbm.xml，该文件的路径必须被写入核心配置文件中的mapping标签中，否则将无法映射

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
        "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
        "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">

<hibernate-mapping package="com.oracle.model"> 
  <class name="Person" table="t_person">
    <id name="id" column="id">
      <generator class="native"></generator>
    </id>
    <property name="realName" column="real_name" length="30"></property>
    <property name="sex" column="sex" length="10"></property>
  </class>
</hibernate-mapping>

<hibernate-mapping>中package属性为映射所在的包名
<class>中name属性为映射的类名，table为该简单java类在数据库中对应的表名
<id>name属性为类中对应的变量名，column是对应数据库中的字段名，generator标签是生成策略，设置为native的意思是使该列成为主键并且自增
<property>为属性标签，用来映射类中变量对应数据库中的字段

5.测试
创建测试类

package com.oracle.service;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;public class Demo {

    public static void main(String[] args) {
        //首先实例化核心配置文件hibernate.cfg.xml
        Configuration configuration=new Configuration().configure();
        //实例化服务登记，，复制粘贴
        ServiceRegistry serviceRegistry=new StandardServiceRegistryBuilder().applySettings(configuration.getProperties()).build(); 
        //创建Session工厂
        SessionFactory sessionFactory=configuration.buildSessionFactory(serviceRegistry); 
        Session session=sessionFactory.openSession(); //生成一个session
        session.beginTransaction(); //开启事务
        
        //先运行程序，生产数据库表

        session.getTransaction().commit(); //提交事务
        session.close(); //关闭session
        sessionFactory.close(); //关闭session工厂
    }

}

运行之前必须现在SQLyog中创建hibernate.cfg.xml中对应的数据库，此例中为hibernate_demo02

然后直接运行程序，如果没有表，则会逆向由java实体自动创建一张数据库表