hibernate3.5.6版本 使用annotation出现org.hibernate.MappingException异常

Question

数据库都是对的，删掉Teacher类的所有有关代码运行正确，加上之后哪个运行都报错。这是怎么回事的 求各位大侠们帮帮忙，高分回报···
引入的包信息：错误信息：（测试TeacherTest类）
Exception in thread "main" org.hibernate.MappingException: Unknown entity: org.zkx.hibernate.model.Teacher
at org.hibernate.impl.SessionFactoryImpl.getEntityPersister(SessionFactoryImpl.java:706)
at org.hibernate.impl.SessionImpl.getEntityPersister(SessionImpl.java:1475)
at org.hibernate.event.def.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:121)
at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.saveWithGeneratedOrRequestedId(DefaultSaveOrUpdateEventListener.java:210)
at org.hibernate.event.def.DefaultSaveEventListener.saveWithGeneratedOrRequestedId(DefaultSaveEventListener.java:56)
at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.entityIsTransient(DefaultSaveOrUpdateEventListener.java:195)
at org.hibernate.event.def.DefaultSaveEventListener.performSaveOrUpdate(DefaultSaveEventListener.java:50)
at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.onSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:93)
at org.hibernate.impl.SessionImpl.fireSave(SessionImpl.java:705)
at org.hibernate.impl.SessionImpl.save(SessionImpl.java:693)
at org.hibernate.impl.SessionImpl.save(SessionImpl.java:689)
at org.zkx.demo.TeacherTest.main(TeacherTest.java:20)
hibernate.cfg.xml配置
<?xml version='1.0' encoding='utf-8'?>
<!DOCTYPE hibernate-configuration PUBLIC
        "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
        "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd"><hibernate-configuration>    <session-factory>
        <!-- Database connection settings -->
        <property name="connection.driver_class">com.mysql.jdbc.Driver</property>
        <property name="connection.url">jdbc:mysql://localhost/hibernate</property>
        <property name="connection.username">root</property>
        <property name="connection.password">zhukexue</property>
        <!-- JDBC connection pool (use the built-in) -->
        <property name="connection.pool_size">1</property> 
        <!-- SQL dialect -->
        <property name="dialect">org.hibernate.dialect.MySQLDialect</property>
        <!-- Enable Hibernate's automatic session context management -->
        <property name="current_session_context_class">thread</property>
        <!-- Disable the second-level cache  -->
        <property name="cache.provider_class">org.hibernate.cache.NoCacheProvider</property>
       <!-- Echo all executed SQL to stdout -->
        <property name="show_sql">true</property>
        <!-- Drop and re-create the database schema on startup -->
        <property name="hbm2ddl.auto">update</property>
        <mapping resource="org/zkx/hibernate/model/Student.hbm.xml"/>
        <mapping class="org.zkx.hibernate.model.Teacher"/>   
    </session-factory>
</hibernate-configuration>Student.hbm.xml配置文件
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
        "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
        "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping package="org.zkx.hibernate.model">
<class name="Student">
<id name="id" />
<property name="name"></property>
<property name="age"></property>
</class>
</hibernate-mapping>Teacher类
package org.zkx.hibernate.model;
import javax.persistence.Id;
import org.hibernate.annotations.Entity;
@Entity
public class Teacher {
private int id;
private String name;
private String title;
@Id
public int getId() {
return id;
}

public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getTitle() {
return title;
}
public void setTitle(String title) {
this.title = title;
}
}StudentTest测试类
package org.zkx.demo;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.AnnotationConfiguration;
import org.hibernate.cfg.Configuration;
import org.zkx.hibernate.model.Teacher;
public class TeacherTest {
public static void main(String args[]){
Teacher t=new Teacher();
t.setId(2);
t.setName("wangwu");
t.setTitle("45");
 Configuration cft=new AnnotationConfiguration();
 SessionFactory sf=cft.configure().buildSessionFactory();
 Session session=sf.openSession();
 session.beginTransaction();
 session.save(t);
 session.getTransaction().commit();
 session.close();
 sf.close();
}
}Student类：
package org.zkx.hibernate.model;
public class Student {
private int id;
private String name;
private int age;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
}StudentTest类：
package org.zkx.demo;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;
import org.zkx.hibernate.model.Student;
public class StudentTest {
public static void main(String args[]){
 Student s=new Student();
 s.setId(2);
 s.setName("zhangsan");
 s.setAge(3);  
 Configuration cft=new Configuration();
 SessionFactory sf=cft.configure().buildSessionFactory();
 Session session=sf.openSession();
 session.beginTransaction();
 session.save(s);
 session.getTransaction().commit();
 session.close();
 sf.close();
}
}