text/src/web/servlet/student/StudentListServlet.java

package web.servlet.student;

import domain.Admin;
import domain.Student;
import domain.Teacher;
import service.StudentService;
import service.impl.StudentServiceImpl;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.io.IOException;
import java.util.List;

@WebServlet("/studentListServlet")
public class StudentListServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //调用StudentService完成查询-
        StudentService studentService = new StudentServiceImpl();
        List<Student> students = studentService.findAll();
        //将list存入request域-
        request.setAttribute("students",students);

        request.setCharacterEncoding("utf-8");

        // 获取当前会话
        HttpSession session = request.getSession();
        // 从会话中获取学生对象
        Student student= (Student)session.getAttribute("student");
        // 从会话中获取管理员对象
        Admin admin= (Admin)session.getAttribute("admin");
        // 从会话中获取教师对象
        Teacher teacher= (Teacher)session.getAttribute("teacher");
        // 如果会话中存在学生对象，且不存在管理员对象和教师对象，则跳转到学生列表页面
        if (student != null && admin == null && teacher == null) {
            request.getRequestDispatcher("/WEB-INF/student/studentList.jsp").forward(request, response);
        // 如果会话中存在管理员对象，且不存在学生对象和教师对象，则跳转到管理员查找学生列表页面
        } else if (admin != null && student == null && teacher == null) {
            request.getRequestDispatcher("/WEB-INF/admin/aFindStudentList.jsp").forward(request, response);
        // 如果会话中存在教师对象，且不存在学生对象和管理员对象，则跳转到教师查找学生列表页面
        } else if (teacher != null && admin == null && student == null) {
            request.getRequestDispatcher("/WEB-INF/teacher/tFindStudentList.jsp").forward(request, response);
        // 如果会话中不存在学生对象、管理员对象和教师对象，则跳转到错误页面
        } else {
            request.getRequestDispatcher("error.jsp").forward(request, response);
        }
    }
    //   HttpSession session = request.getSession();
    //        Student student= (Student)session.getAttribute("student");
    //        Admin admin= (Admin)session.getAttribute("admin");
    //        Teacher teacher= (Teacher)session.getAttribute("teacher");
    //        if (student != null && admin == null && teacher == null) {
    //            request.getRequestDispatcher("/WEB-INF/student/studentList.jsp").forward(request, response);
    //        } else if (admin != null && student == null && teacher == null) {
    //            request.getRequestDispatcher("/WEB-INF/admin/aFindStudentList.jsp").forward(request, response);
    //        } else if (teacher != null && admin == null && student == null) {
    //            request.getRequestDispatcher("/WEB-INF/teacher/tFindStudentList.jsp").forward(request, response);
    //        } else {
    //            request.getRequestDispatcher("error.jsp").forward(request, response);
    //        }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        this.doPost(request,response);
    }
}
//package web.servlet.student;
//
//import domain.Admin;
//import domain.Student;
//import domain.Teacher;
//import service.StudentService;
//import service.impl.StudentServiceImpl;
//
//import javax.servlet.ServletException;
//import javax.servlet.annotation.WebServlet;
//import javax.servlet.http.HttpServlet;
//import javax.servlet.http.HttpServletRequest;
//import javax.servlet.http.HttpServletResponse;
//import javax.servlet.http.HttpSession;
//import java.io.IOException;
//import java.util.List;
//
//@WebServlet("/studentListServlet")
//public class StudentListServlet extends HttpServlet {
//    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//        //调用StudentService完成查询-
//        StudentService studentService = new StudentServiceImpl();
//        List<Student> students = studentService.findAll();
//        //将list存入request域-
//        request.setAttribute("students",students);
//
//        request.setCharacterEncoding("utf-8");
//
//        // 获取当前会话
//        HttpSession session = request.getSession();
//        // 从会话中获取学生对象
//        Student student= (Student)session.getAttribute("student");
//        // 从会话中获取管理员对象
//        Admin admin= (Admin)session.getAttribute("admin");
//        // 从会话中获取教师对象
//        Teacher teacher= (Teacher)session.getAttribute("teacher");
//        // 如果会话中存在学生对象，且不存在管理员对象和教师对象，则跳转到学生列表页面
//        if (student != null && admin == null && teacher == null) {
//            request.getRequestDispatcher("/WEB-INF/student/studentList.jsp").forward(request, response);
//        // 如果会话中存在管理员对象，且不存在学生对象和教师对象，则跳转到管理员查找学生列表页面
//        } else if (admin != null && student == null && teacher == null) {
//            request.getRequestDispatcher("/WEB-INF/admin/aFindStudentList.jsp").forward(request, response);
//        // 如果会话中存在教师对象，且不存在学生对象和管理员对象，则跳转到教师查找学生列表页面
//        } else if (teacher != null && admin == null && student == null) {
//            request.getRequestDispatcher("/WEB-INF/teacher/tFindStudentList.jsp").forward(request, response);
//        // 如果会话中不存在学生对象、管理员对象和教师对象，则跳转到错误页面
//        } else {
//            request.getRequestDispatcher("error.jsp").forward(request, response);
//        }
//    }
//    //   HttpSession session = request.getSession();
//    //        Student student= (Student)session.getAttribute("student");
//    //        Admin admin= (Admin)session.getAttribute("admin");
//    //        Teacher teacher= (Teacher)session.getAttribute("teacher");
//    //        if (student != null && admin == null && teacher == null) {
//    //            request.getRequestDispatcher("/WEB-INF/student/studentList.jsp").forward(request, response);
//    //        } else if (admin != null && student == null && teacher == null) {
//    //            request.getRequestDispatcher("/WEB-INF/admin/aFindStudentList.jsp").forward(request, response);
//    //        } else if (teacher != null && admin == null && student == null) {
//    //            request.getRequestDispatcher("/WEB-INF/teacher/tFindStudentList.jsp").forward(request, response);
//    //        } else {
//    //            request.getRequestDispatcher("error.jsp").forward(request, response);
//    //        }
//
//    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//        this.doPost(request,response);
//    }
//}