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();
         }
     }