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

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

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

<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>

@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();
		}
	}