开始前还是说点废话，虽然上一篇已经写了Hibernate的小程序这次就不用写了，直接拷贝过来改改就行了，但是这样最终的目的还是达不到几天肯定就忘了hibernate的配置了为了熟练期间还是不厌其烦的从头再来。
第一步:新建Java项目用来Main测试hibernate的例子，创建项目包一共创建三个 com.ygc.hibernate.modle |com.ygc.hibernate.test | com.ygc.hibernate.utils分别解释下modle包用来存放bean对象的，test包用来写测试代码的就是main方法的，utils就是用来存放工具类的。本例中就不用手动创建表了，首先编写Modle类
package com.ygc.hibernate.modle;
import java.io.Serializable;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Table;
@Entity
@Table(name = "Music")
public class Music implements Serializable {
private int id;
private String musicName;
private String author;
private String musicType;
@Id
@GeneratedValue(strategy=GenerationType.AUTO) //主键自动增长
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getMusicName() {
return musicName;
}
public void setMusicName(String musicName) {
this.musicName = musicName;
}
public String getAuthor() {
return author;
}
public void setAuthor(String author) {
this.author = author;
}
public String getMusicType() {
return musicType;
}
public void setMusicType(String musicType) {
this.musicType = musicType;
}
}
上面注意的地方要添加@Entity注解 Table指定表名 设置主键自动增长，主要的一点说清楚导包一定要导import javax.persistence.Entity;这个包，导入其他包会出现各种各样的问题。
第二步:编写main方法测试类
package com.ygc.hibernate.main;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import com.ygc.hibernate.modle.Music;
import com.ygc.hibernate.utils.HibernateUtils;
public class MusicTest {
public static void main(String[] args) {
Music music = new Music();
//id是自动增长的所以就不用在此处设置了
music.setAuthor("任贤齐");
music.setMusicName("爱的路上只有我和你");
music.setMusicType("浪漫型");
SessionFactory sFactory = HibernateUtils.getHibernateUtils().getSessionFactory();
Session session = sFactory.openSession();
session.beginTransaction();
session.save(music);
session.getTransaction().commit();
session.close();
sFactory.close();
}
}
第三步:编写工具类供主方法测试调用
package com.ygc.hibernate.utils;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.AnnotationConfiguration;
import org.hibernate.cfg.Configuration;
public class HibernateUtils {
private static HibernateUtils instance;
public static HibernateUtils getHibernateUtils(){
if(instance==null){
instance=new HibernateUtils();
}
return instance;
}
public SessionFactory getSessionFactory(){
Configuration configuration = new AnnotationConfiguration().configure();
return configuration.buildSessionFactory();
}
}
第四步:添加hibernate配置文件名称为hibernate.cfg.xml并且添加log4j的配置
<?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/hibernate</property>
<property name="connection.username">root</property>
<property name="connection.password">root</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>
<!--自动创建表-->
<property name="hbm2ddl.auto">create</property>
<!-- Drop and re-create the database schema on startup -->
<!--<property name="hbm2ddl.auto">update</property>-->
<!--<mapping resource="com/ygc/hibernate/modle/Students.hbm.xml"/>-->
<mapping class="com.ygc.hibernate.modle.Music"/>
</session-factory>
</hibernate-configuration>
本例的重点说明下在配置中加了<property name="hbm2ddl.auto">create</property>这个配置才能创建属性值有好几个，分别有validate | update | create | create-drop
validate 加载hibernate时，验证创建数据库表结构
create 每次加载hibernate，重新创建数据库表结构，这就是导致数据库表数据丢失的原因。
create-drop 加载hibernate时创建，退出是删除表结构
update 加载hibernate自动更新数据库结构
第五步:log4j的配置文件
# Configure logging for testing: optionally with log file # debug,info,warn,error,fatal log4j.rootLogger=debug, stdout, logfile log4j.appender.stdout=org.apache.log4j.ConsoleAppender log4j.appender.stdout.layout=org.apache.log4j.PatternLayout log4j.appender.stdout.layout.ConversionPattern=%d %p [%c] - %m%n log4j.appender.logfile=org.apache.log4j.FileAppender log4j.appender.logfile.File=D:/logs/hibernate.log log4j.appender.logfile.layout=org.apache.log4j.PatternLayout log4j.appender.logfile.layout.ConversionPattern=%d %p [%c] - %m%n log4j.logger.org.hibernate.tool.hbm2ddl=debug
第六步:查看运行结果。在cmd启动mysql 并且登陆mysql 在对应的数据库下面查看自己的表的数据
mysql> show tables; +---------------------+ | Tables_in_hibernate | +---------------------+ | music | | students | | teacher | | xuxudan | +---------------------+ 4 rows in set (0.06 sec)
mysql> select * from music; +----+--------+--------------------+-----------+ | id | author | musicName | musicType | +----+--------+--------------------+-----------+ | 1 | 任贤齐 | 爱的路上只有我和你 | 浪漫型 | +----+--------+--------------------+-----------+ 1 row in set (0.00 sec)
第七步:已经完了没有第七步了。最后把Demo给献上如果有bug请提出也给我一个学习的机会 谢谢。
Demo下载地址：下载 所用到的Jar包下载: jar包上传有点慢明晚共享出来...