Hibernate update无法更新问题
代码如下：
  public class StudentOperate {
private Session session=null;
public StudentOperate(){
Configuration configuration = new Configuration().configure();
SessionFactory factory = configuration.buildSessionFactory();
this.session = factory.openSession();
}
  public void update(Student o,Serializable id){
Transaction t = this.session.beginTransaction();
Student c =(Student)session.load(o.getClass(),id);

c.getId().setAge(new Integer(30));//要更新的值
System.out.println(c.getId().getName());

this.session.update(c);

this.session.flush();
t.commit();
this.session.close();

}
  ｝
测试代码：
public class Testdom {
public static void main(String[] args){
Integer id1 = new Integer(1);

Integer age1 = new Integer(20);

Student student = new Student();

StudentId s1 = new StudentId(id1,"李建刚",age1);

StudentOperate studentoperate = new StudentOperate();

studentoperate.update(student,s1);
}

}
配置文件：
<hibernate-mapping>
  <class name="com.Student" table="student" catalog="school" dynamic-update="true">
  <composite-id name="id" class="com.StudentId" >
  <key-property name="id" type="java.lang.Integer">
  <column name="id" />
  </key-property>
  <key-property name="name" type="java.lang.String">
  <column name="name" length="50" />
  </key-property>
  <key-property name="age" type="java.lang.Integer">
  <column name="age" />
  </key-property>
  </composite-id>
  </class>
</hibernate-mapping>
程序执行后无法更新数据库，请问各位这是什么原因？

------解决方案--------------------
c.getId().setAge(new Integer(30));//要更新的值
这一行怎么解释，难道c.getId()返回的是一个Student对象？
------解决方案--------------------

探讨

c.getId().setAge(new Integer(30));//要更新的值
这一行怎么解释，难道c.getId()返回的是一个Student对象？