帮我用javaweb写一下学生信息管理系统的servlet类

当然可以，以下是一个简单的学生信息管理系统的Servlet类的示例：

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

@WebServlet("/student")
public class StudentServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;
    
    private List<Student> students;

    public void init() {
        students = new ArrayList<>();
        students.add(new Student("John", "Doe", 20));
        students.add(new Student("Jane", "Smith", 22));
    }

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

        if (action == null) {
            action = "list";
        }

        switch (action) {
            case "list":
                listStudents(request, response);
                break;
            case "add":
                showAddForm(request, response);
                break;
            case "edit":
                showEditForm(request, response);
                break;
            case "delete":
                deleteStudent(request, response);
                break;
            default:
                listStudents(request, response);
                break;
        }
    }

    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        String action = request.getParameter("action");

        if (action == null) {
            action = "list";
        }

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

    private void listStudents(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        request.setAttribute("students", students);
        request.getRequestDispatcher("list.jsp").forward(request, response);
    }

    private void showAddForm(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        request.getRequestDispatcher("add.jsp").forward(request, response);
    }

    private void showEditForm(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        int id = Integer.parseInt(request.getParameter("id"));
        Student student = getStudentById(id);

        request.setAttribute("student", student);
        request.getRequestDispatcher("edit.jsp").forward(request, response);
    }

    private void addStudent(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        String firstName = request.getParameter("firstName");
        String lastName = request.getParameter("lastName");
        int age = Integer.parseInt(request.getParameter("age"));

        students.add(new Student(firstName, lastName, age));
        response.sendRedirect("student");
    }

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

        Student student = getStudentById(id);
        student.setFirstName(firstName);
        student.setLastName(lastName);
        student.setAge(age);

        response.sendRedirect("student");
    }

    private void deleteStudent(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        int id = Integer.parseInt(request.getParameter("id"));
        Student student = getStudentById(id);
        students.remove(student);

        response.sendRedirect("student");
    }

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

此示例中的Servlet类包含了以下功能：

• 显示学生列表
• 显示添加学生表单
• 显示编辑学生表单
• 添加学生
• 更新学生信息
• 删除学生

你可以根据自己的需求修改和扩展这个示例。请注意，此示例仅用于演示目的，可能需要根据你的具体需求进行适当的修改。