一个Hibernate的Hello World, 基于Hibernate 4.0

先在官网上下载最近的Hibernate完整包, 目前最新的是hibernate-release-4.0.0.Final http://www.hibernate.org/downloads .

 

打开Myeclipse, 新建一个JavaProject. 

1.导入Hibernate需要的Jar包.

　　需要加入的包有:hibernate-release-4.0.0.Final里面Lib目录下Required的所有Jar包.

2.加入Hibernate配置文件hibernate.cfg.xml, 文件内容可参考文档(这里使用的是么Mysql):

<?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>
    <!-- Database connection settings -->
    <property name="connection.driver_class">
        com.mysql.jdbc.Driver
    </property>
    <property name="connection.url">
        jdbc:mysql://localhost:3306/hibernate
    </property>
    <property name="connection.username">用户名</property>
    <property name="connection.password">密码</property>

    <!-- JDBC connection pool (use the built-in) 
        <property name="connection.pool_size">1</property>
    -->
    <!-- SQL dialect -->
    <property name="dialect">
        org.hibernate.dialect.MySQLDialect
    </property>

    <!-- Enable Hibernate's automatic session context management 
        <property name="current_session_context_class">thread</property>
    -->
    <!-- Disable the second-level cache  -->
    <property name="cache.provider_class">
        org.hibernate.cache.internal.NoCacheProvider
    </property>

    <!-- Echo all executed SQL to stdout -->
    <property name="show_sql">true</property>

    <!-- Drop and re-create the database schema on startup 
        <property name="hbm2ddl.auto">update</property>-->
    <property name="myeclipse.connection.profile">
        Hibernate_Test
    </property>
    <mapping resource="jyu/hibernate/model/Student.hbm.xml" />
    <mapping class="jyu.hibernate.model.Teacher" />
</session-factory>
</hibernate-configuration>

3.新建一个实体类Student, 并成长get, set方法:

package jyu.hibernate.model;

public class Student {
    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;
    }
    
    
}

4.在数据库中建好对应的表Student, 有id, name ,age三个字段.

5.编写实体与关系的映射文件:Student.hbm.xml

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

<hibernate-mapping>
    <class name="jyu.hibernate.model.Student">
        <id name="id" column="id"/>
        <property name="name" />
        <property name="age" />
    </class>
    
</hibernate-mapping>

6.在hibernate.cfg.xml配置文件中加入Student.hbm.xml:在 </session-factory> 之前加入:<mapping resource="jyu/hibernate/model/Student.hbm.xml" />

7.测试:StudentTest

 

package jyu.hibernate.model;

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

public class StudentTest {
    
    public static void main(String[] agrs){
        Student st = new Student();
        st.setId(2);
        st.setName("学生");
        st.setAge(20);
        
        Configuration cfg = new Configuration();    //读取配置hibernate文件
        SessionFactory  sf = cfg.configure().buildSessionFactory(); //根据配置文件生成事务工厂
        Session session = sf.openSession();
        session.beginTransaction();                    //事务开启
        session.save(st);                            //保存对象
        session.getTransaction().commit();
        session.close();    
        sf.close();
    }
}

运行, 可以查看到数据库中已经插入了一条记录.

这种方法是比较常用的使用XML来映射实体与关系的方法, 另有使用Annotation(注解)方式也能完成映射功能.

 

本文为尚学堂马士兵Hibernate视频教程笔记.