关于struts2 select标签的使用问题，请大家帮忙看看啦！感激不尽
用select标签时一直有这个问题，找了很多方法都不知道怎么解决，
<s:select name="classid" list="#request.classArray" 
headerKey="0" headerValue="==请选择=="
listKey="classid" listValue="classname" value="ClassId">
  </s:select>
错误：tag 'select', field 'list', name 'classid': The requested list key '#request.classArray' could not be resolved as a collection/array/map/enumeration/iterator type. Example: people or people.{name}
我也知道这可能是因为List属性中没有初值，因为把List中的值换成这样就能显示了：
<s:select name="classid" list="#{0:'ooo',1:'aaa'}" 
headerKey="0" headerValue="==请选择=="
listKey="classid" listValue="classname" value="ClassId">
  </s:select>
但不是说list属性中没有初值是，加了headerKye,headerValue就可以了的么？？
这问题困扰很久了。请帮忙解决下。感激不尽啊！

classviewAction如下：希望大家能帮我看看怎么解决
public class ClassViewAction extends ActionSupport {

private static final long serialVersionUID = 1L;
public String action;
public String classid;
@Override
public String execute() throws Exception {
Connection conn=DBConn.createDBConn();
String sql="select * from ClassTa";
Statement stclass=conn.createStatement();
ResultSet rsclass=stclass.executeQuery(sql);
ArrayList<ClassTa> classArray=new ArrayList<ClassTa>();
while(rsclass.next()){
ClassTa classta=new ClassTa();
classta.setClassid(rsclass.getInt("classid"));
classta.setClassname(rsclass.getString("classname"));
classArray.add(classta);
}
Map request = (Map)ActionContext.getContext().get("request");
request.put("classArray", classArray);
if(classid!=null&&classid.length()!=0){
sql="select * from student where classid="+classid;
Statement state=conn.createStatement();
ResultSet rs=state.executeQuery(sql);
ArrayList<Student> stuArray=new ArrayList<Student>();
while(rs.next()){
Student stu=new Student();
stu.setBedchamberId(rs.getInt("bedchamberId"));
stu.setClassId(rs.getInt("classId"));
stu.setMatriNo(rs.getString("matriNo"));
stu.setPayAmount(rs.getFloat("payAmount"));
stu.setPayOK(rs.getInt("payOK"));
stu.setRegistDate(rs.getDate("registDate"));
stu.setSpecialityId(rs.getInt("specialityId"));
stu.setStudentId(rs.getLong("studentId"));
stu.setStudentName(rs.getString("studentName"));
stuArray.add(stu);
}
request.put("stuArray", stuArray);
}
DBConn.closeConn(conn);
return SUCCESS;
}
public String getAction() {
return action;
}
public void setAction(String action) {
this.action = action;
}
public String getClassid() {
return classid;
}
public void setClassid(String classid) {
this.classid = classid;
}

}

------解决方案--------------------
list="#request.classArray",你这样写有数据时能获取到从后台传过来的值？
我常用的方法是：在action中定义classArray类，然后生成它的get、set方法，在页面直接用list="classArray"就搞定了。
The requested list key '#request.classArray' could not be resolved as a collection
------解决方案--------------------

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list="#request.classArray",你这样写有数据时能获取到从后台传过来的值？
我常用的方法是：在action中定义classArray类，然后生成它的get、set方法，在页面直接用list="classArray"就搞定了。
The requested list key '#request.classArray' could not be resolved as a c……