求助，新手学hibernate4.1.4遇到问题
最近学习hibernate，第一个例子就出问题了，解决了几个，有出现一个新的，这个没找到方法解决，所以来求助各位前辈！

hibernate.cfg.xml的配置如下：
<?xml version='1.0' encoding='utf-8'?>
<!DOCTYPE hibernate-configuration PUBLIC
  "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
  "http://www.hibernate.org/dtd/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">mysql</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.internal.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="com/dxd/hibernate/model/Student.hbm.xml"/>-->
  <mapping class="com.dxd.hibernate.model.Student"/>
  </session-factory>

</hibernate-configuration>

Student.java如下：
package com.dxd.hibernate.model;

import javax.persistence.Entity;
import javax.persistence.Id;

@Entity
public class Student {
  private int id;
  private String name;
  private int age;
  @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 int getAge() {
  return age;
  }
  public void setAge(int age) {
  this.age = age;
  }
   
}

测试类StudentTest.java如下：
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistryBuilder;

import com.dxd.hibernate.model.Student;


public class StudentTest {
  public static void main(String[] args) {
  Student student=new Student();
  student.setId(1);
  student.setName("nihao");
  student.setAge(20);
  Configuration cfg=new Configuration();
  SessionFactory sf=cfg.configure().buildSessionFactory(ne