基于List集合映射

1、 实体类中使用List集合

public class Grade {
    private int id;
    private String name;
    private List<Student> students = new ArrayList<Student>(0);
}

2、 映射文件

<hibernate-mapping package="cn.siggy.pojo">
    <class name="Grade">
        <id name="id">
            <generator class="native"></generator>
        </id>
        <property name="name"/>
        <list name="students" cascade="all">
            <!-- key表示外键  column外键列名-->
            <key column="grade_id"></key>
            <!-- 在多的一端 产生一列 用来表示顺序 如果不指明列名 默认为 idx 
                值由hibernate来维护
             -->
            <list-index column="sort">
            </list-index>
            <!-- one-to-many 一对多  类Grade 中  students 所表示类型 -->
            <one-to-many class="Student"/>
        </list>
    </class>

3、 测试代码

@Test
    public void testSave() throws HibernateException, SerialException, SQLException{
        Configuration cfg = new Configuration().configure();
        SessionFactory factory = cfg.buildSessionFactory(new StandardServiceRegistryBuilder()
        .applySettings(cfg.getProperties()).build());
        Session session = null;
        Transaction tx = null;
        try{
            session = factory.openSession();
            tx = session.beginTransaction();
            Grade grade = new Grade();
            grade.setName("基础");
            
            Student stu = new Student();
            stu.setName("张三疯");
            stu.setAge(22);
            Student stu1 = new Student();
            stu1.setName("老王");
            stu1.setAge(23);
            Student stu2 = new Student();
            stu2.setName("老李");
            stu2.setAge(23);
            //关联
            grade.getStudents().add(stu);
            grade.getStudents().add(stu1);
            grade.getStudents().add(stu2);
            //保存数据的顺序 是根据外键的配置来决定的
            //如果外键不能为null,那么先保存一的一端
            //如果外键可以为null,则可以随意保存
            session.save(grade);
            session.save(stu);
            session.save(stu1);
            session.save(stu2);
            
            tx.commit();
            
        }catch (HibernateException e) {
            if(tx!=null)
                tx.rollback();
            e.printStackTrace();
            throw e;
        }finally{
            HibernateUtil.closeSession();
        }
    }
    @Test
    public void testGet(){
        Session session = null;
        Transaction tx = null;
        try{
            session = HibernateUtil.getSession();
            tx = session.beginTransaction();
            //取数据
            Grade grade = (Grade)session.get(Grade.class, 1);
            System.out.println("gradeName="+grade.getName());
            System.out.println("grade所对应的多的一端的数据");
            List<Student> list = grade.getStudents();
            for(Student stu:list){
                System.out.println(stu.getName());
            }
            tx.commit();
        }catch (HibernateException e) {
            if(tx!=null)
                tx.rollback();
            e.printStackTrace();
            throw e;
        }finally{
            HibernateUtil.closeSession();
        }
    }