Dwr实现级联菜单的问题

1、目的：实现 学院、专业、班级的级联，采用的框架为Struts2+spring+ibatis+dwr，但是在使用dwr时，直接去读的service中的方法，和struts没有关系！
2、第一步就出现问题，无法读出学院信息
(1)在java中的代码如下CollegeServiceImpl.java：
    //查询所有学院
    @SuppressWarnings("unchecked")
    public List<College> getAllCollege() {
        return collegeDAO.getAllCollege();
    }
我做过测试在这个方法里能打印出学院的列表。(2)jsp页面中的代码listCollege.jsp      <script type='text/javascript' src='/student/dwr/interface/DWR_getCollege.js'></script>
      <script type='text/javascript' src='/student/dwr/interface/DWR_getZy.js'></script>
      <script type='text/javascript' src='/student/dwr/interface/DWR_getBj.js'></script>
      <script type='text/javascript' src='/student/dwr/engine.js'></script>
      <script type="text/javascript" src="/student/dwr/util.js"></script>
      
      
      <script type="text/javascript">      function getAllCollege(){
         DWR_getCollege.getAllCollege(setCollege);
    }
    function setCollege(data){
        college.innerHTML="";//如果有值就清空
        college.add(new Option('请选择',''));
                         for(var i=0;i<data.length;i++){
                                alert(data.Cxy);
                              //college.add(new Option(data.Cxy,data.Markxy));
                        }  
                    }
我只贴出了一个函数，这个函数功能就是获得学院的列表。但是每次测试出来的值都为空？为什么呢？
(3)相关的配置文件dwr.xml
                       <allow>
        <create creator="spring" javascript="DWR_getCollege">
            <param name="beanName" value="collegeService" />
        </create>
        <create creator="spring" javascript="DWR_getZy">
            <param name="beanName" value="zyService" />
        </create>
        <create creator="spring" javascript="DWR_getBj">
            <param name="beanName" value="bjService" />
        </create>
        <create creator="new" javascript="service">
            <param name="class" value="helloWorld.Service" />
        </create>
        
        <convert converter="bean" match="com.student.model.College">
        <param name="include" value="Id,Cxy,Exy,Markxy" /> 
        </convert>
        <convert converter="bean" match="com.student.model.Zy">
        <param name="include" value="Id,Czy,Ezy,Markzy" /> 
        </convert>
        <convert converter="bean" match="com.student.model.Bj">
        <param name="include" value="Id,Cbj,Ebj,Markbj" /> 
        </convert>    </allow>
web.xml的配置：
<servlet>
        <servlet-name>dwr-invoker</servlet-name>
        <servlet-class>
            org.directwebremoting.servlet.DwrServlet
        </servlet-class>
        <!-- 
            <init-param>
            <param-name>config</param-name>
            <param-value>/WEB-INF/dwr.xml</param-value>
            </init-param>
        -->
        <init-param>
            <param-name>debug</param-name>
            <param-value>true</param-value>
        </init-param>
        <load-on-startup>0</load-on-startup>
    </servlet>    <context-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>classpath:spring.xml</param-value>
    </context-param>
    <filter>
        <filter-name>struts2</filter-name>
        <filter-class>
            org.apache.struts2.dispatcher.FilterDispatcher
        </filter-class>
    </filter>
    <filter-mapping>
        <filter-name>struts2</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>
    <servlet-mapping>
        <servlet-name>dwr-invoker</servlet-name>
        <url-pattern>/dwr/*</url-pattern>
    </servlet-mapping>    <listener>
        <listener-class>
            org.springframework.web.context.ContextLoaderListener
        </listener-class>
    </listener>
spring中的配置：
    <!-- 学院开始 -->
    <bean id="collegeDAO" class="com.student.dao.CollegeDAOImpl">
        <property name="dataSource">
            <ref local="dataSource" />
        </property>
        <property name="sqlMapClient">
            <ref local="sqlMapClient" />
        </property>
    </bean>
    <bean id="collegeService" parent="baseTransactionProxy">
        <property name="target">
            <bean class="com.student.service.CollegeServiceImpl">
                <property name="collegeDAO">
                    <ref bean="collegeDAO" />
                </property>
            </bean>
        </property>
    </bean>
    <bean id="collegeAction" class="com.student.action.CollegeAction"
        singleton="false">
        <property name="collegeService">
            <ref bean="collegeService" />
        </property>
    </bean>
    <!-- 学院结束 -->
3、问题描述：第一步在jsp页面中就无法获得学院的列表，但是在CollegeServiceImpl.java这个中的方法是能够获得学院列表的？请高人指点这到底是什么原因，是配置出错了吗？还是其他原因？