用Javaweb写一个学生信息管理系统包含dao类 model类 servlet类

以下是一个简单的学生信息管理系统的示例代码：

1. DAO类（StudentDAO.java）：

import java.util.ArrayList;
import java.util.List;

public class StudentDAO {
    private static List<Student> students = new ArrayList<>();

    public void addStudent(Student student) {
        students.add(student);
    }

    public void updateStudent(Student student) {
        for (int i = 0; i < students.size(); i++) {
            if (students.get(i).getId() == student.getId()) {
                students.set(i, student);
                break;
            }
        }
    }

    public void deleteStudent(int id) {
        for (int i = 0; i < students.size(); i++) {
            if (students.get(i).getId() == id) {
                students.remove(i);
                break;
            }
        }
    }

    public List<Student> getAllStudents() {
        return students;
    }

    public Student getStudentById(int id) {
        for (Student student : students) {
            if (student.getId() == id) {
                return student;
            }
        }
        return null;
    }
}

2. Model类（Student.java）：

public class Student {
    private int id;
    private String name;
    private String grade;
    private String department;

    public Student(int id, String name, String grade, String department) {
        this.id = id;
        this.name = name;
        this.grade = grade;
        this.department = department;
    }

    // Getters and setters

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getGrade() {
        return grade;
    }

    public void setGrade(String grade) {
        this.grade = grade;
    }

    public String getDepartment() {
        return department;
    }

    public void setDepartment(String department) {
        this.department = department;
    }
}

3. Servlet类（StudentServlet.java）：

import java.io.IOException;
import java.util.List;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class StudentServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;
    private StudentDAO studentDAO;

    public void init() {
        studentDAO = new StudentDAO();
    }

    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        doGet(request, response);
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        String action = request.getServletPath();

        switch (action) {
            case "/add":
                addStudent(request, response);
                break;
            case "/edit":
                editStudent(request, response);
                break;
            case "/update":
                updateStudent(request, response);
                break;
            case "/delete":
                deleteStudent(request, response);
                break;
            default:
                listStudents(request, response);
                break;
        }
    }

    private void addStudent(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        String name = request.getParameter("name");
        String grade = request.getParameter("grade");
        String department = request.getParameter("department");

        Student student = new Student(studentDAO.getAllStudents().size() + 1, name, grade, department);
        studentDAO.addStudent(student);
        response.sendRedirect("list");
    }

    private void editStudent(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        int id = Integer.parseInt(request.getParameter("id"));
        Student student = studentDAO.getStudentById(id);
        request.setAttribute("student", student);
        request.getRequestDispatcher("edit.jsp").forward(request, response);
    }

    private void updateStudent(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        int id = Integer.parseInt(request.getParameter("id"));
        String name = request.getParameter("name");
        String grade = request.getParameter("grade");
        String department = request.getParameter("department");

        Student student = new Student(id, name, grade, department);
        studentDAO.updateStudent(student);
        response.sendRedirect("list");
    }

    private void deleteStudent(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        int id = Integer.parseInt(request.getParameter("id"));
        studentDAO.deleteStudent(id);
        response.sendRedirect("list");
    }

    private void listStudents(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        List<Student> students = studentDAO.getAllStudents();
        request.setAttribute("students", students);
        request.getRequestDispatcher("list.jsp").forward(request, response);
    }
}

以上是一个简单的学生信息管理系统的代码示例，包含了DAO类、Model类和Servlet类。你可以根据自己的需求进行修改和扩展。