hibernate入门
作为新手刚学hibernate不久，发表一篇博客同时也为自己做做总结。
一、开始前准备三步骤：
1、导入hibernate所需要的jar包以及数据库连接包
2、配置hibernate.cfg.xml配置文件
<?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>
<property name="myeclipse.connection.profile">oracel</property>
<property name="connection.url">
jdbc:mysql://localhost:3306/mathmodeling
</property>
<property name="connection.username">root</property>
<property name="connection.password">admin</property>
<property name="connection.driver_class">
com.mysql.jdbc.Driver
</property>
<property name="dialect">
org.hibernate.dialect.MySQLDialect
</property>
<property name="show_sql">true</property>
<mapping resource="com/ccsu/bean/News.hbm.xml" />
</session-factory>
</hibernate-configuration>
3建立实体类以及实体类映射文件（比如News类对应的文件News.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">
<!--
Mapping file autogenerated by MyEclipse - Hibernate Tools
-->
<hibernate-mapping>
<class name="com.ccsu.bean.News" table="news" catalog="mathmodeling">
<id name="nid" type="java.lang.Integer">
<column name="nid" />
<generator class="identity" />
</id>
<property name="subject" type="string">
<column name="subject" length="50" not-null="true" />
</property>
<property name="content" type="string">
<column name="content" length="3000" not-null="true" />
</property>
<property name="display" type="java.lang.Boolean">
<column name="display" length="3" not-null="true" />
</property>
<property name="createTime" type="timestamp">
<column name="createTime" length="20" not-null="true" />
</property>
<property name="updateTime" type="timestamp">
<column name="updateTime" length="20" />
</property>
<property name="type" type="java.lang.Integer">
<column name="type" not-null="true" />
</property>
</class>
</hibernate-mapping>
二、使用hibernate的七个步骤
1、读取配置文件
Configuration conf = new Configuration().config();
2、创建sessionFactory
SessionFactory sf = conf.buildSessionFactory();
3打开session
Session session = sf.openSession();
4开启事物
Transaction tx = session.beginTransaction();
5经行数据操作
News news =new News();
....
session.save(news);
6提交事物
tx.commit()
7最为重要的不能忘记关闭连接
session.close();
三hibernate的查询
1HQL语句查询
编写HQL语句 String hql =“select news from News(千万记住是类名) news where news.content like '啊哈'”
得到Query Query query = session.createQuery(hql );
执行查询得到结果 List list = query.list();
2Criteria查询
Criteria c = session.createCriteria(类.class);