struts2的注册方法发出空指针
这是struts.xml
<?xml version="1.0" encoding="UTF-8"?>
 <!DOCTYPE struts PUBLIC
"-//Apache Software Foundation//DTD Struts Configuration 2.3//EN"
"http://struts.apache.org/dtds/struts-2.3.dtd">
<struts>
   <!-- struts报错的友好提示 -->
   <constant name="struts.devMode" value="true"/>
   <!-- 统一修改struts表单标签中的样式 -->
   <constant name="struts.ui.theme" value="simple"></constant>
   <!-- 指定action由spring来创建 -->
   <constant name="struts.objectFactory" value="spring"></constant>
   <package name="default" namespace="/" extends="struts-default">
      <action name="employee_*" class="employeeAction" method="{1}">
        <result name="loginUI">/login.jsp</result>
      </action>
   </package>
</struts>
employee-beans.xml
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
xmlns:context="http://www.springframework.org/schema/context"
xmlns:aop="http://www.springframework.org/schema/aop"
xmlns:tx="http://www.springframework.org/schema/tx"
xsi:schemaLocation="http://www.springframework.org/schema/beans 
http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/context 
http://www.springframework.org/schema/context/spring-context.xsd
http://www.springframework.org/schema/aop
http://www.springframework.org/schema/aop/spring-aop.xsd
http://www.springframework.org/schema/tx 
http://www.springframework.org/schema/tx/spring-tx.xsd
">


    <!-- 配置action -->
    <bean id="employeeAction" class="cn.itcast.action.EmployeeAction" scope="prototype"></bean>
    
    <!-- 配置EmployeeDao -->
    <bean id="employeeDao" class="cn.itcast.dao.EmployeeDao">
        <property name="sessionFactory" ref="sessionFactory"></property>
    </bean>
    
    <!-- 配置EmployeeService -->
    <bean id="employeeService" class="cn.itcast.service.EmployeeService">
        <property name="employeeDao" ref="employeeDao"></property>
    </bean>
    
    
</beans>

Action的注册方法
public class EmployeeAction extends ActionSupport implements ModelDriven<Employee> {

//创建模型驱动，收集客户端的参数
Employee model = new Employee();
public Employee getModel() {
return model;
}
    
//引入service
private IEmployeeService employeeService;
//xml方式所提供的set()方法
public void setIemployeeService(IEm