Hibernate初探

1.下载Hibernate，点击下载(版本号3.2.5GA)

2.新建java项目，导入Hibernate库以及mysql库

3.新建主配置文件hibernate.cfg.xml

<!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="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property><!--指定驱动,这部分与JDBC很相似--><property name="hibernate.connection.url">jdbc:mysql:///test</property><property name="hibernate.connection.username">root</property><property name="hibernate.connection.password">123456</property><property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property><!--针对mysql的特点，例如分页limit的处理方式为mysql特有--><property name="hibernate.hbm2ddl.auto">create</property><!--开发阶段，可以使用此参数来告诉hibernate在初始化时创建数据库--><mapping resource="test/User.hbm.xml"/><!--指定hibernate对象配置路径,hibernate需要通过此配置文件将关系型转换为JAVA的对象型。多个表可以建立多个mapping--></session-factory></hibernate-configuration> 

4.新建User.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 package="test"><!-- package属性指定类所在路径 --><class name="User" table="user"><!-- name:指定类名称,table:对应表名称。 若没有table属性时，默认使用类名 --><id name="id" column="id"><!-- 每个配置文件，必须有一个主键 。name:类的属性名，column:对应字段名。默认使用name作为字段名--><generator class="native"/><!-- 指定自动增长方式，Native主键生成方式会根据不同的底层数据库自动选择Identity、Sequence、Hilo主键生成方式 --></id><property name="name"/><!-- name:类的属性名，column:对应字段名。默认使用name作为字段名--><property name="berthdate"/></class></hibernate-mapping> 

5.新建User类，对应与user表

/** * 为每个字段设置setter/getter */package test;import java.util.Date;public class User {private int id;private String name;private Date berthdate;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 Date getBerthdate() {return berthdate;}public void setBerthdate(Date berthdate) {this.berthdate = berthdate;}} 

6.建立Hibernate工具类

package common.plugs;import org.hibernate.Session;import org.hibernate.SessionFactory;import org.hibernate.Transaction;import org.hibernate.cfg.Configuration;public final class HibernateUtil {private static SessionFactory sessionFactory;private HibernateUtil(){}static{Configuration cfg = new Configuration();cfg.configure();sessionFactory = cfg.buildSessionFactory();}public static SessionFactory getSessionFactory(){return sessionFactory;}public static Session getSession(){return sessionFactory.openSession();}public static void add(Object entity){Session s = null;try{s = HibernateUtil.getSession();Transaction tx = s.beginTransaction();s.save(entity);tx.commit();}finally{if(s != null)s.close();}}public static void update(Object entity){Session s = null;try{s = HibernateUtil.getSession();Transaction tx = s.beginTransaction();s.update(entity);tx.commit();}finally{if(s != null)s.close();}}public static void delete(Object entity){Session s = null;try{s = HibernateUtil.getSession();Transaction tx = s.beginTransaction();s.delete(entity);tx.commit();}finally{if(s != null)s.close();}}public static Object get(Class clazz, int id){Session s = null;try{s = HibernateUtil.getSession();return s.get(clazz, id);}finally{if( s != null)s.close();}}} 

7.建立测试类

package test;import java.util.Date;import org.hibernate.Session;import org.hibernate.SessionFactory;import org.hibernate.Transaction;import org.hibernate.cfg.Configuration;import common.plugs.HibernateUtil;public class Base {/** * @param args */public static void main(String[] args) {User user = new User();user.setBerthdate(new Date());user.setName("test");HibernateUtil.add(user);System.out.println("id:"+user.getId());User u = (User) HibernateUtil.get(user.getClass(), 1);System.out.println("username:" + u.getName());}public static User getUser(int id){Session s = null;User result = null;try{s = HibernateUtil.getSession();User user = new User();result = (User) s.get(user.getClass(), id);}finally{s.close();}return result;}}