HibernateDemo

Hibernate是当前最流行的ORM框架，ORM即Object/Relation Mapping, 对象关系数据库映射。

ORM是一种规范：完成面向对象语言到关系数据库的映射。

本文将演示一个最简单的demo，完成往数据库中添加记录的功能。

准备工作：

本文采用Hibernate 3.6.0版本，用到的jar包如下图：

一个典型的Hibernate Demo应该包含一下三个文件：

　　1. PO，持久化对象。利用它可完成持久化操作。Hibearnate是低侵入式的设计，只需一个POJO（普通java对象）即可，无需继承任何父类和接口。

　　2. *.hbm.xml。POJO与数据库表之间的映射配置文件。

　　3. *.cfg.xml。Hibernate的配置文件，包括数据库驱动、URL、用户名、密码等信息。

数据库表：

use hibernateDemo;
drop table if exists TMP_EMP;

create table TMP_EMP (
  ID       int(4) primary key,
  NAME     VARCHAR(50),
  BIRTHDAY DATE,
  SEX      CHAR(1),
  SALARY   float(8,2)
);

POJO：

// default package
// Generated 2013-4-29 17:04:49 by Hibernate Tools 3.4.0.CR1

import java.util.Date;

/**
 * TmpEmp generated by hbm2java
 */
public class TmpEmp implements java.io.Serializable {

    private int id;
    private String name;
    private Date birthday;
    private Character sex;
    private Float salary;

    public TmpEmp() {
    }

    public TmpEmp(int id) {
        this.id = id;
    }

    public TmpEmp(int id, String name, Date birthday, Character sex,
            Float salary) {
        this.id = id;
        this.name = name;
        this.birthday = birthday;
        this.sex = sex;
        this.salary = salary;
    }

    public int getId() {
        return this.id;
    }

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

    public String getName() {
        return this.name;
    }

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

    public Date getBirthday() {
        return this.birthday;
    }

    public void setBirthday(Date birthday) {
        this.birthday = birthday;
    }

    public Character getSex() {
        return this.sex;
    }

    public void setSex(Character sex) {
        this.sex = sex;
    }

    public Float getSalary() {
        return this.salary;
    }

    public void setSalary(Float salary) {
        this.salary = salary;
    }

}

hibernate.cfg.xml

<?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 name="">
  <property name="hibernate.connection.driver_class">org.gjt.mm.mysql.Driver</property>
  <property name="hibernate.connection.password">wailiee</property>
  <property name="hibernate.connection.url">jdbc:mysql://localhost:3306/HibernateDemo</property>
  <property name="hibernate.connection.username">root</property>
  <property name="hibernate.dialect">org.hibernate.dialect.MySQLInnoDBDialect</property>
  <mapping resource="TmpEmp.hbm.xml"/>
 </session-factory>
</hibernate-configuration>

TmpEmp.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">
<!-- Generated 2013-4-29 17:07:22 by Hibernate Tools 3.4.0.CR1 -->
<hibernate-mapping>
    <class name="TmpEmp" table="TMP_EMP">
        <id name="id" type="int">
            <column name="ID" />
            <!-- 指定主键生成策略 -->
            <generator class="assigned" />
        </id>
        <property name="name" type="java.lang.String">
            <column name="NAME" />
        </property>
        <property name="birthday" type="java.util.Date">
            <column name="BIRTHDAY" />
        </property>
        <property name="sex" type="java.lang.Character">
            <column name="SEX" />
        </property>
        <property name="salary" type="java.lang.Float">
            <column name="SALARY" />
        </property>
    </class>
</hibernate-mapping>

Client

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


public class Client0 {

    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        Configuration conf = new Configuration();
        // 下面的方法默认加载hibernate.cfg.xml文件
        conf.configure();
        
        // 创建sessionFactory
        SessionFactory sf = conf.buildSessionFactory();
        // 创建session
        Session sess = sf.openSession();
        // 开始事务,Hibernate必须显式的手动提交事务
        Transaction tx = sess.beginTransaction();
        
        TmpEmp tmpEmp = new TmpEmp();
        tmpEmp.setId(5);
        tmpEmp.setName("yz");
        
        // 保存
        sess.save(tmpEmp);
        
        // 提交事务
        tx.commit();
        
        // 关闭session
        sess.flush();
        sess.close();
        sf.close();
    }

}

运行结果：