单向多对一的关联映射

1、学生表student 和年级表grade

2、类Student 和Grade类

Student:

1 public class Student {
2     private int id;
3     private String name;
4     private int age;
5     private Grade grade;
6 //get…set
7 }

Grade:

1 public class Grade {
2     private int id;
3     private String name;
4     //get…set
5 }

3、映射文件

Grade.hbm.xml

1 <hibernate-mapping package="cn.siggy.pojo">
2     <class name="Grade">
3         <id name="id">
4             <generator class="native"></generator>
5         </id>
6         <property name="name"/>
7     </class>
8 </hibernate-mapping>

Student.hbm.xml

 1 <hibernate-mapping package="cn.siggy.pojo">
 2     <class name="Student">
 3         <id name="id">
 4             <generator class="native"></generator>
 5         </id>
 6         <property name="name"/>
 7         <property name="age"/>
 8         <!-- 多对一  name 表示属性名  class 指明 属性对应的类 
 9          column指 数据库表中的列名 -->
10             <many-to-one name="grade" class="Grade" 
11         column="grade_id" foreign-key="fk_grade" not-null="true"/>    
12 　　</class>
13 </hibernate-mapping>

4、测试代码

 1 @Test
 2     public void testSave() throws HibernateException, SerialException, SQLException{
 3         Session session = null;
 4         Transaction tx = null;
 5         try{
 6             session = HibernateUtil.getSession();
 7             tx = session.beginTransaction();
 8             Grade grade = new Grade();
 9             grade.setName("基础");
10             session.save(grade);
11             Student stu = new Student();
12             stu.setName("张三疯");
13             stu.setAge(22);
14             stu.setGrade(grade);
15             session.save(stu);
16             
17             tx.commit();
18             
19         }catch (HibernateException e) {
20             if(tx!=null)
21                 tx.rollback();
22             e.printStackTrace();
23             throw e;
24         }finally{
25             HibernateUtil.closeSession();
26         }
27     }