今天开始学Hibernate了,按照先脉络后细节、先操作后原理的学习顺序,那么第一个要学习的就是Hibernate版的HelloWorld了,即如何连接并操作数据库。
Hibernate是什么,Hibernate有什么作用,先撇开不谈,现在我们只知道Hibernate是对JDBC的进一步封装即可。
一、第一个案例
实验环境:Hibernate3.3.2+SQL Server 2005
实验步骤:
(1)、新建Java项目(Hibernate是一个非常独立的框架)
(2)、引入相应的jar包
a)Hibernate所需jar包
- hibernate core
- /required
- slf-nop jar
b)SQL Server所需的JDBC驱动包
(3)在SQL Server中建立对应的数据库以及表
create database hibernate; use hibernate; create table Student (id int primary key, namevarchar(20), age int);
(4)新建和配置Hibernate的配置文件hibernate.cfg.xm
<?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> <!-- Database connection settings --> <property name="connection.driver_class">com.microsoft.sqlserver.jdbc.SQLServerDriver</property> <property name="connection.url">jdbc:sqlserver://127.0.0.1:1433;DatabaseName=hibernate</property> <property name="connection.username">sa</property> <property name="connection.password">123456</property> <!-- JDBC connection pool (use the built-in) --> <!-- <property name="connection.pool_size">1</property> --> <!-- SQL dialect --> <property name="dialect">org.hibernate.dialect.SQLServerDialect</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/chongqing/hibernate/model/Student.hbm.xml"/> </session-factory> </hibernate-configuration>
(5)建立Student 类
package com.chongqing.hibernate.model; public class Student { private int id; private String name; private int age; public int getId() { return id; } public String getName() { return name; } public int getAge() { return age; } public void setId(int id) { this.id = id; } public void setName(String name) { this.name = name; } public void setAge(int age) { this.age = age; } }
(6)建立Student 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 package="com.chongqing.hibernate.model"> <class name="Student"> <id name="id"></id> <property name="name"></property> <property name="age"></property> </class> </hibernate-mapping>
(7)写测试类Main,在Main中对Student对象进行直接的存储测试
import org.hibernate.Session; import org.hibernate.SessionFactory; import org.hibernate.cfg.Configuration; import com.chongqing.hibernate.model.Student; public class StudentTest { public static void main(String[] args) { // TODO Auto-generated method stub Student s = new Student(); s.setId(1); s.setName("s1"); s.setAge(1); //创建Configuration,该对象用于读取hibernate.cfg.xml配置文件,并完成初始化 Configuration cfg = new Configuration().configure(); //创建SessionFactory,一个SessionFactory对应一个数据存储源 SessionFactory sf = cfg.buildSessionFactory(); //创建session,相当于JDBC中的Connection,主要此处的session并不是web中的session, Session session = sf.openSession(); //Hibernate要求在进行增加,删除,修改的时候使用事务 session.beginTransaction(); session.save(s); //提交 session.getTransaction().commit(); session.close(); sf.close(); } }
二、Annotation版本的HelloWorld
使用Annotation可以不用配置映射文件Student.hbm.xml,直接在实体类上建立相关的注解:
import org.hibernate.Session; import org.hibernate.SessionFactory; import org.hibernate.cfg.AnnotationConfiguration; import org.hibernate.cfg.Configuration; import com.chongqing.hibernate.model.Student; public class StudentTest { public static void main(String[] args) { Student s = new Student(); s.setId(3); s.setName("s3"); s.setAge(3); //注意这里要使用org.hibernate.cfg.AnnotationConfiguration来创建Configuration,才能使用Annotation功能 Configuration cfg = new AnnotationConfiguration(); SessionFactory sf = cfg.configure().buildSessionFactory(); Session session = sf.openSession(); session.beginTransaction(); session.save(s); session.getTransaction().commit(); session.close(); sf.close(); } }
需要在Hibernate lib中加入Annotation的jar包:
- hibernate annotaion jar
- ejb3 persistence jar
- hibernate common-annotations.jar
及在配置文件hibernate.cfg.xm建立映射为:
<mapping class="com.chongqing.hibernate.model.Student"/>