关于spring整合hibernate出现的错误
我自学spring框架的时在整合hibernate的时候出现了以下的问题：
Exception in thread "main" org.springframework.orm.hibernate3.HibernateSystemException: ids for this class must be manually assigned before calling save(): Employee.Employee; nested exception is org.hibernate.id.IdentifierGenerationException: ids for this class must be manually assigned before calling save(): Employee.Employee
Caused by: org.hibernate.id.IdentifierGenerationException: ids for this class must be manually assigned before calling save(): Employee.Employee
at org.hibernate.id.Assigned.generate(Assigned.java:53)
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:713)
at org.hibernate.impl.SessionImpl.save(SessionImpl.java:701)
at org.hibernate.impl.SessionImpl.save(SessionImpl.java:697)
at org.springframework.orm.hibernate3.HibernateTemplate$12.doInHibernate(HibernateTemplate.java:635)
at org.springframework.orm.hibernate3.HibernateTemplate.execute(HibernateTemplate.java:372)
at org.springframework.orm.hibernate3.HibernateTemplate.save(HibernateTemplate.java:632)
at Employee.EmployeeDaoImpl.add(EmployeeDaoImpl.java:15)
at Employee.EmployeeDaoImpl.main(EmployeeDaoImpl.java:20)
我找了很久不知道是哪里错了，请大家帮我看下，

以下是我的配置文件和测试类
applicationContext.xml配置文件
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-2.0.xsd">
<bean id="sessionFactory" class="org.springframework.orm.hibernate3.LocalSessionFactoryBean">
  <property name="configLocation" value="classpath:hibernate.cfg.xml"></property>
</bean>
<bean id="EmployeeDaoImpl" class="Employee.EmployeeDaoImpl">
<property name="sessionFactory" ref="sessionFactory"></property>
</bean>
</beans>

hibernate配置文件
<?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">

<!-- Generated by MyEclipse Hibernate Tools. -->
<hibernate-configuration>

<session-factory>
<property name="dialect">
org.hibernate.dialect.MySQLDialect
</property>
<property name="conne