第一个Hibernate小程序

使用hibernate3.6.8作为此次学习的hibernate版本，根据官方的手册来学习。算是做一个学习笔记吧，不然照着官方文档做一遍就忘了，加深记忆 O(∩_∩)O~。谁叫出去面试都问ssh呢

一、第一个Hibernate小程序
搭建一个可以存储事件(Event)的小程序
1. 实现我们的第一个类Event，一个标准的JavaBean

package com.iteye.hibernate.domain;

import java.util.Date;

public class Event {
	private Long id;

	private String title;
	private Date date;

	public Event() {
	}

	public Long getId() {
		return id;
	}

	private void setId(Long id) {
		this.id = id;
	}

	public Date getDate() {
		return date;
	}

	public void setDate(Date date) {
		this.date = date;
	}

	public String getTitle() {
		return title;
	}

	public void setTitle(String title) {
		this.title = title;
	}
}

2. 创建我们的mapping文件
Event.hbm.xml

<?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.iteye.hibernate.domain">
	<class name="Event" table="EVENTS">
		<id name="id" column="EVENT_ID">
			<generator class="native"/>
		</id>
		<property name="date" type="timestamp" column="EVENT_DATE"/>
		<property name="title"/>
	</class>
</hibernate-mapping>

3. 进行hibernate的配置
现在你已经有了一个java类和一个Event的映射文件，接下来来配置hibernate的配置文件。在src目录下新建hibernate.cfg.xml

<?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">oracle.jdbc.driver.OracleDriver</property>
        <property name="connection.url">jdbc:oracle:thin:@urhost:1521:urdb</property>
        <property name="connection.username">urname</property>
        <property name="connection.password">urpwd</property>

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

        <!-- SQL dialect -->
        <property name="dialect">org.hibernate.dialect.OracleDialect</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.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>

        <mapping resource="com/iteye/hibernate/domain/Event.hbm.xml"/>

    </session-factory>
</hibernate-configuration>

上面的文件中配置了Hibernate的SessionFactory。SessionFactory是一个数据库的全局工厂，用于和数据库的连接。如果你有多个数据了，那你可以在不同的hibernate配置文件中配置多个SessionFactory
4. 配置必须的jar包
把hibernate-distribution-3.6.8.Final\lib\required目录下的所有jar包，\hibernate-distribution-3.6.8.Final\目录下的hibernate3.jar以及\hibernate-distribution-3.6.8.Final\lib\jpa 下的hibernate-jpa-2.0-api-1.0.1.Final.jar
和oracle的JDBC驱动加入到项目的classpath中

5. 创建一个帮助类来帮助获取SessionFactory实例
HibernateUtil.java

package com.iteye.hibernate.util;

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

public class HibernateUtil {
	private static final SessionFactory sessionFactory = buildSessionFactory();
	
	private static SessionFactory buildSessionFactory() {
		return new Configuration().configure().buildSessionFactory();
	}
	
	public static SessionFactory getSessionFactory() {
		return sessionFactory;
	}

}
6.	创建测试类来运行我们的程序
EventManager.java
package com.iteye.hibernate;

import java.util.Date;

import org.hibernate.Session;

import com.iteye.hibernate.domain.Event;
import com.iteye.hibernate.util.HibernateUtil;

public class EventManager {
	public static void main(String[] args) {
		EventManager mgr = new EventManager();
		mgr.createAndStoreEvent("My Event", new Date());
		HibernateUtil.getSessionFactory().close();
	}

	private void createAndStoreEvent(String title, Date theDate) {
		Session session = HibernateUtil.getSessionFactory().getCurrentSession();
		session.beginTransaction();

		Event theEvent = new Event();
		theEvent.setTitle(title);
		theEvent.setDate(theDate);
		session.save(theEvent);
		session.getTransaction().commit();
	}

}

然后运行此类，至此我们的第一个Hibernate小程序运行成功
你会在Console看到如下sql语句

Hibernate: select hibernate_sequence.nextval from dual
Hibernate: insert into EVENTS (EVENT_DATE, title, EVENT_ID) values (?, ?, ?)

说明数据已经插入数据库

第一个Hibernate小程序

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