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:

public class Student {
    private int id;
    private String name;
    private int age;
    private Grade grade;
//get…set
}

Grade:

public class Grade {
    private int id;
    private String name;
    //get…set
}

3、 映射文件

Grade.hbm.xml

<hibernate-mapping package="cn.siggy.pojo">
    <class name="Grade">
        <id name="id">
            <generator class="native"></generator>
        </id>
        <property name="name"/>
    </class>
</hibernate-mapping>

Student.hbm.xml

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

4、 测试代码

 

 

@Test
    public void testSave() throws HibernateException, SerialException, SQLException{
        Session session = null;
        Transaction tx = null;
        try{
            session = HibernateUtil.getSession();
            tx = session.beginTransaction();
            Grade grade = new Grade();
            grade.setName("基础");
            session.save(grade);
            Student stu = new Student();
            stu.setName("张三疯");
            stu.setAge(22);
            stu.setGrade(grade);
            session.save(stu);
            
            tx.commit();
            
        }catch (HibernateException e) {
            if(tx!=null)
                tx.rollback();
            e.printStackTrace();
            throw e;
        }finally{
            HibernateUtil.closeSession();
        }
    }