hibernate映射组成关系

package com.hibernate.helloworld;

public class School {
     private String name;
     private String address;
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public String getAddress() {
        return address;
    }
    public void setAddress(String address) {
        this.address = address;
    }
    public School(String name, String address) {
        super();
        this.name = name;
        this.address = address;
    }
    public School() {
        super();
        // TODO Auto-generated constructor stub
    }
    @Override
    public String toString() {
        return "School [name=" + name + ", address=" + address + "]";
    }
    
     
}


package com.hibernate.helloworld;

import java.util.Date;

public class Student {
    private Integer id;
    private String name;
    private Date birth;
    private School school;
    
    
    public Student() {
        // TODO Auto-generated constructor stub
    }
    public Student(String name, Date birth) {
        super();
        this.name = name;
        this.birth = birth;
    }
    public Integer getId() {
        return id;
    }
    public void setId(Integer id) {
        this.id = id;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public Date getBirth() {
        return birth;
    }
    public void setBirth(Date birth) {
        this.birth = birth;
    }
    
    
    public School getSchool() {
        return school;
    }
    public void setSchool(School school) {
        this.school = school;
    }
    @Override
    public String toString() {
        return "Student [id=" + id + ", name=" + name + ", birth=" + birth + ", school=" + school + "]";
    }
    
    
}

<?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>
    <!-- 配置连接数据库的基本信息 -->
        <property name="connection.username">root</property>
        <property name="connection.password">1</property>
        <property name="connection.driver_class">com.mysql.jdbc.Driver</property>
        <property name="connection.url">jdbc:mysql://127.0.0.1:3306/test?useUnicode=true&amp;characterEncoding=UTF-8</property>

        <!-- 配置 hibernate 的基本信息 -->
        <property name="dialect">org.hibernate.dialect.MySQLInnoDBDialect</property>

        <!-- 执行操作时是否在控制台打印 SQL -->
        <property name="show_sql">true</property>

        <!-- 是否对 SQL 进行格式化 -->
        <property name="format_sql">true</property>

        <!-- 指定自动生成数据表的策略 -->
        <property name="hbm2ddl.auto">update</property>

        <!-- 指定关联的 .hbm.xml 文件 -->
        <mapping resource="com/hibernate/helloworld/Student.hbm.xml" />
    </session-factory>
</hibernate-configuration>

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<!-- Generated 2017-8-7 21:15:19 by Hibernate Tools 3.4.0.CR1 -->
<hibernate-mapping package="com.hibernate.helloworld">
    <class name="Student" table="STUDENT" dynamic-insert="true">
        <id name="id" type="java.lang.Integer">
            <column name="ID" />
            <generator class="native" />
        </id>
        <property name="name" type="java.lang.String">
            <column name="NAME" />
        </property>
        <property name="birth" type="java.util.Date">
            <column name="BIRTH" />
        </property>
        
        <component name="school" class="School">
            <property name="name" column="SCHOOL_NAME"></property>
            <property name="address" column="SCHOOL_ADDRESS"></property>
        </component>
    </class>
</hibernate-mapping>

package com.hibernate.helloworld;

import java.sql.Date;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;
import org.hibernate.service.ServiceRegistryBuilder;
import org.junit.Test;

public class test {

    @Test
    public void test() {
        
        System.out.println("test...");
        
        //1. 创建一个 SessionFactory 对象
        SessionFactory sessionFactory = null;
        
        //1). 创建 Configuration 对象: 对应 hibernate 的基本配置信息和 对象关系映射信息
        Configuration configuration = new Configuration().configure();
        
        //4.0 之前这样创建
//        sessionFactory = configuration.buildSessionFactory();
        
        //2). 创建一个 ServiceRegistry 对象: hibernate 4.x 新添加的对象
        //hibernate 的任何配置和服务都需要在该对象中注册后才能有效.
        ServiceRegistry serviceRegistry = 
                new ServiceRegistryBuilder().applySettings(configuration.getProperties())
                                            .buildServiceRegistry();
        
        //3).
        sessionFactory = configuration.buildSessionFactory(serviceRegistry);
        
        //2. 创建一个 Session 对象
        Session session = sessionFactory.openSession();
        
        //3. 开启事务
        Transaction transaction = session.beginTransaction();
        
        //4. 执行保存操作
        Student student = new Student("刘备", new Date(new java.util.Date().getTime()));
        School school = new School("AAA","BBB");
        student.setSchool(school);
        session.save(student);
        
        //5. 提交事务 
        transaction.commit();
        
        //6. 关闭 Session
        session.close();
        
        //7. 关闭 SessionFactory 对象
        sessionFactory.close();
    }
    
}