hibernate基础

<!--hibernate.cfg.xml  -->
<?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可以理解为一个Connection工厂或者Connection池  -->
    <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">bjsxt</property>

        <!-- 这个是hibernate自带的连接池用的不多，一般使用applicaton Server用JNDI注册的连接池>
        <property name="connection.pool_size">1</property>

        <!-- SQL dialect(方言)，参考文档 -->
        <property name="dialect">org.hibernate.dialect.MySQLDialect</property>

        <!-- Enable Hibernate‘s automatic session context management，后面讲 -->
        <!-- <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,hibernate自动生成建表语句，后面讲 -->
        <!--  <property name="hbm2ddl.auto">update</property>-->

        <mapping resource="com/bjsxt/hibernate/Student.hbm.xml"/>
    </session-factory>
</hibernate-configuration>

public class Student {
    //省略set、get
    private int id;
    private String name;
    private int age;
}

<!--Student.hbm.xml,名称固定，按约定俗称写，放在和Student类相同包下  -->
<?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>
    <class name="com.bjsxt.hibernate.Student">
        <id name="id" />
        <property name="name" />//不写column默认和name一样
        <property name="age" />
    </class>
</hibernate-mapping>

//测试类
public class Test {
    public static void main(String[] args) {
        Student s = new Student();
        s.setId(1);
        s.setName("zhangsan");
        s.setAge(8);

        SessionFactory sessionFactory = new AnnotationConfiguration()
                .configure().buildSessionFactory();
        Session session = sessionFactory.getCurrentSession();// 可以把Session理解为Connection
        session.beginTransaction();// hibernate必须开启事务
        session.save(s);// 这样就把数据插入到了数据库中
        session.getTransaction().commit();
    }
}