看你自己是否使用ModelDriven的方法

如果使用這種方法，實現了未定義的接口

就緒要查看一下你自己的 getModel這個方式是不是使用的默認 return null

如果是的話，修改代碼就可以正常獲取表單中的數據

package?action;

import?java.util.List;

import?com.opensymphony.xwork2.ModelDriven;

import?entity.Students;
import?service.StudentsDAO;
import?service.impl.StudentsDAOImpl;

//學生Action類
public?class?StudentsAction?extends?SuperAction?implements?ModelDriven<Students>?{

????/**
?????*?
?????*/
????private?static?final?long?serialVersionUID?=?1L;
????
????Students?student?=?new?Students();
????
????//查詢所有學生動作
????public?String?query()?{
????????StudentsDAO?studentDao?=?new?StudentsDAOImpl();
????????
????????List<Students>?list?=?studentDao.quertAllStudents();
????????//放進session里面
????????if?(list?!=?null?&&?list.size()?>?0)?{
????????????session.setAttribute("students_list",?list);
????????}
????????return?"Student_query_success";
????}
????
????//刪除學生信息動作
????public?String?delete()?{
????????StudentsDAO?studentDao?=?new?StudentsDAOImpl();
????????String?sid?=?request.getParameter("sid");
????????studentDao.deleteStudents(sid);
????????return?"delete_success";
????}
????
????//添加學生信息動作
????public?String?add()?{
????????StudentsDAO?studentDao?=?new?StudentsDAOImpl();
????????if?(studentDao.addStudents(student))?{
????????????return?"add_success";
????????}
????????return?"add_failure";
????}
????
????//添加修改學生資料動作
????public?String?modify()?{
????????//獲得傳遞過來的學生編號
????????String?sid?=?request.getParameter("sid");
????????StudentsDAO?studentDao?=?new?StudentsDAOImpl();
????????Students?s?=?studentDao.queryStudentsBySid(sid);
????????session.setAttribute("modify_students",?s);
????????return?"modify_success";
????}
????
????//
????public?String?save()?{
????????StudentsDAO?studentDao?=?new?StudentsDAOImpl();
????????if?(studentDao.updateStudents(student))?{
????????????return?"save_success";
????????}
????????return?"save_failure";
????}
????@Override
????public?Students?getModel()?{
????????//?TODO?Auto-generated?method?stub
????????return?this.student;
????}
}