问一个使用Hibernate时的一个错误

初学Hibernate，刚开始就受挫了，麻烦各位大侠帮忙。先介绍一下我的情况：
数据库：mysql 5.X
表：
| Table | Create Table+-------+------------------------------------
---------------------------------------------
| user  | CREATE TABLE `user` (
  `id` int(11) NOT NULL,
  `username` varchar(200) default NULL,
  PRIMARY KEY  (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1 |
+-------+------------------------------------
---------------------------------------------java文件：
public class User { private Long userId;
private String userName;
public Long getUserId() {
return userId;
}
public void setUserId(Long userId) {
this.userId = userId;
}
public String getUserName() {
return userName;
}
public void setUserName(String userName) {
this.userName = userName;
}

}Hibernate文件：         <class name="User" table="User">
<id name="userId" column="id" type="java.lang.Long" length="4">
</id>
<property name="userName" type="int" column="userName" />
</class>测试代码：
                  Session session = HibernateSessionFactory.currentSession();
Transaction transaction = session.beginTransaction();
User user = new User();
user.setUserName("ss");
user.setUserId(new Long(2));
session.save(user); transaction.commit();
出现错误：Hibernate: insert into User (userName, id) values (?, ?)
java.lang.ClassCastException
at org.hibernate.type.IntegerType.set(IntegerType.java:39)
at org.hibernate.type.NullableType.nullSafeSet(NullableType.java:62)
at org.hibernate.type.NullableType.nullSafeSet(NullableType.java:39)
at org.hibernate.persister.entity.BasicEntityPersister.dehydrate(BasicEntityPersister.java:1617)
at org.hibernate.persister.entity.BasicEntityPersister.dehydrate(BasicEntityPersister.java:1594)
at org.hibernate.persister.entity.BasicEntityPersister.insert(BasicEntityPersister.java:1850)
at org.hibernate.persister.entity.BasicEntityPersister.insert(BasicEntityPersister.java:2200)
at org.hibernate.action.EntityInsertAction.execute(EntityInsertAction.java:46)
at org.hibernate.engine.ActionQueue.execute(ActionQueue.java:239)
at org.hibernate.engine.ActionQueue.executeActions(ActionQueue.java:223)
at org.hibernate.engine.ActionQueue.executeActions(ActionQueue.java:136)
at org.hibernate.event.def.AbstractFlushingEventListener.performExecutions(AbstractFlushingEventListener.java:274)
at org.hibernate.event.def.DefaultFlushEventListener.onFlush(DefaultFlushEventListener.java:27)
at org.hibernate.impl.SessionImpl.flush(SessionImpl.java:730)
at org.hibernate.impl.SessionImpl.managedFlush(SessionImpl.java:324)
at org.hibernate.transaction.JDBCTransaction.commit(JDBCTransaction.java:86)
at ttTest.main(ttTest.java:20)
Exception in thread "main" 谢谢各位能看看，小弟我到底是犯了什么毛病。谢谢！！！！！！！！！！