Hibernate4学习之一对多关系配置(四)

一对多关系的实现
1.hibernate.cfg.xml

<?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>

        <!--数据库连接设置 -->
        <property name="connection.driver_class">com.mysql.jdbc.Driver</property>
        <property name="connection.url">jdbc:mysql://localhost:3306/hibernate</property>
        <property name="connection.username">root</property>
        <property name="connection.password">123456</property>


        <!-- 方言 -->
        <property name="dialect">org.hibernate.dialect.MySQL5Dialect</property>

        <!-- 控制台显示SQL -->
        <property name="show_sql">true</property>

        <!-- 自动更新表结构 -->
        <property name="hbm2ddl.auto">update</property>

        <mapping resource="com/newbeedaly/model/Student.hbm.xml"/>

        <mapping resource="com/newbeedaly/model/Class.hbm.xml"/>

    </session-factory>

</hibernate-configuration>

2.Student类和Class类，以及表结构生成配置Student.hbm.xml和Class.hbm.xml

package com.newbeedaly.model;

public class Student {

    private long id;
    private String name;
    private Class c;

    public long getId() {
        return id;
    }
    public void setId(long id) {
        this.id = id;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }


    public Class getC() {
        return c;
    }
    public void setC(Class c) {
        this.c = c;
    }
    @Override
    public String toString() {
        return "Student [id=" + id + ", name=" + name + "]";
    }


}

package com.newbeedaly.model;

public class Class {

    private long id;
    private String name;

    public long getId() {
        return id;
    }
    public void setId(long id) {
        this.id = id;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }


}

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
        "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
        "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">

<hibernate-mapping package="com.newbeedaly.model">

    <class name="Student" table="t_student">
        <id name="id" column="stuId">
            <generator class="native"></generator>
        </id>

        <property name="name" column="stuName"></property>
        <!--  
        班级学生一对多关系的配置：级联关系
        cascade="save-update" 自动保存关联表，如Test2。默认值为none，不保存。
        -->
        <many-to-one name="c" column="classId" class="com.newbeedaly.model.Class" cascade="save-update"></many-to-one>
    </class>

</hibernate-mapping>

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
        "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
        "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">

<hibernate-mapping package="com.newbeedaly.model">

    <class name="Class" table="t_class">
        <id name="id" column="classId">
            <generator class="native"></generator>
        </id>

        <property name="name" column="className"></property>
    </class>

</hibernate-mapping>

3.测试代码StudentTest 和StudentTest 2

package com.newbeedaly.service;

import org.hibernate.Session;
import org.hibernate.SessionFactory;

import com.newbeedaly.model.Class;
import com.newbeedaly.model.Student;
import com.newbeedaly.util.HibernateUtil;

public class StudentTest {

    public static void main(String[] args) {
        SessionFactory sessionFactory=HibernateUtil.getSessionFactory();
        Session session=sessionFactory.openSession(); // 生成一个session
        session.beginTransaction(); // 开启事务

        Class c=new Class();
        c.setName("08计本");
        session.save(c);

        Student s1=new Student();
        s1.setName("张三");
        s1.setC(c);

        Student s2=new Student();
        s2.setName("李四");
        s2.setC(c);

        session.save(s1);
        session.save(s2);

        session.getTransaction().commit(); // 提交事务
        session.close(); // 关闭session
    }
}

package com.newbeedaly.service;

import static org.junit.Assert.*;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.junit.After;
import org.junit.AfterClass;
import org.junit.Before;
import org.junit.BeforeClass;
import org.junit.Test;

import com.newbeedaly.model.Class;
import com.newbeedaly.model.Student;
import com.newbeedaly.util.HibernateUtil;

public class StudentTest2 {

    private SessionFactory sessionFactory=HibernateUtil.getSessionFactory();
    private Session session;

    @Before
    public void setUp() throws Exception {
        session=sessionFactory.openSession(); // 生成一个session
        session.beginTransaction(); // 开启事务
    }

    @After
    public void tearDown() throws Exception {
         session.getTransaction().commit(); // 提交事务
         session.close(); // 关闭session
    }

    @Test
    public void testSaveClassAndStudent() {
        Class c=new Class();
        c.setName("08计本");
        session.save(c);

        Student s1=new Student();
        s1.setName("张三");
        s1.setC(c);

        Student s2=new Student();
        s2.setName("李四");
        s2.setC(c);

        session.save(s1);
        session.save(s2);
    }

    @Test
    public void testSaveClassAndStudentWithCascade() {
        Class c=new Class();
        c.setName("08计本");

        Student s1=new Student();
        s1.setName("张三");
        s1.setC(c);

        Student s2=new Student();
        s2.setName("李四");
        s2.setC(c);

        session.save(s1);
        session.save(s2);
    }

}