Hibernate 学习(1)

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O/R mapping
对象关系映射
把数据库，sql语言f封装成对象，让我们的编程更加对象化
这就是好处
第一步，建立hibernate用户库
这里写图片描述

第二步，建立实体类student

package com.bjsxt.hibernate;public class Student {    private int id;    private String name;    private int age;    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 int getAge() {        return age;    }    public void setAge(int age) {        this.age = age;    }}

如果是用映射文件方式，建立映射文件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"><!-- 这个是映射文件 指定表里面的字段id 是 id成员变量表里面的字段name 是name成员变量表里面的字段age是  age成员变量数据库表不分大小写--><hibernate-mapping>    <class name="com.bjsxt.hibernate.Student" column="student">        <id name="id" column="id"/>        <property name="name" column="name" />        <property name="age" column="age"/>    </class></hibernate-mapping>

hbm就是hibernate mapping的意思

第三步，hibernate.cfg.xml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>        <!-- 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">1995</property>        <!-- JDBC connection pool (use the built-in) -->        <property name="connection.pool_size">1</property>        <!-- SQL dialect 数据库方言，每个数据库软件方言不一样，这里是mysql-->        <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 二级缓存disable -->        <property name="cache.provider_class">org.hibernate.cache.NoCacheProvider</property>        <!-- Echo all executed SQL to stdout就是执行的过程中把生成的sql语句打印出来 -->        <property name="show_sql">true</property>        <!-- Drop and re-create the database schema on startup        hbm hibernate mapping         ddl data define language        hibernate自动帮你生成建立表语句         -->        <property name="hbm2ddl.auto">update</property>        <mapping resource="com/bjsxt/hibernate/Student.hbm.xml"/>        <mapping class="com.bjsxt.hibernate.Teacher"/>    </session-factory></hibernate-configuration>

第四步，写测试程序

package com.bjsxt.hibernate;import org.hibernate.Session;import org.hibernate.SessionFactory;import org.hibernate.cfg.AnnotationConfiguration;public class TeacherTest {    public static void main(String[] args) {        Teacher t = new Teacher();        t.setId(1);        t.setName("t1");        t.setTitle("middle");        SessionFactory sessionFactory = new AnnotationConfiguration().configure().buildSessionFactory();        Session session = sessionFactory.getCurrentSession();        session.beginTransaction();        session.save(t);        session.getTransaction().commit();    }}

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