按規范，我們開發后臺。 新建 TeacherAction，并給teachers變量，開發all()函數。 ``` package com.mengyunzhi.javaee.action; import java.util.ArrayList; import java.util.List; import com.mengyunzhi.javaee.dao.TeacherDao; import com.mengyunzhi.javaee.entity.Teacher; public class TeacherAction extends Action{ private static final long serialVersionUID = 1L; // 定義教師列表 private List<Teacher> teachers = new ArrayList<Teacher>(); public List<Teacher> getTeachers() { return teachers; } @SuppressWarnings("unchecked") public String all() { // 獲取所有數據 TeacherDao teacherDao = new TeacherDao(); this.teachers = (List<Teacher>) teacherDao.all(); return SUCCESS; } } ``` 測試：