用javaweb写一下学生信息管理系统增删改查servlet代码

下面是一个简单的学生信息管理系统的增删改查的Servlet代码示例：

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> studentList;

    public StudentServlet() {
        super();
        studentList = new ArrayList<>();
    }

    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":
                addStudent(request, response);
                break;
            case "edit":
                editStudent(request, response);
                break;
            case "delete":
                deleteStudent(request, response);
                break;
            default:
                listStudents(request, response);
        }
    }

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

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

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

        Student student = new Student(name, age, major);
        studentList.add(student);

        response.sendRedirect("student?action=list");
    }

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

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

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

        response.sendRedirect("student?action=list");
    }
}

这是一个简单的Servlet，它通过GET和POST方法处理不同的操作，包括列出学生列表、添加学生、编辑学生和删除学生。在这个示例中，学生的信息使用一个Student类表示，以便存储在一个List中。在doGet方法中，根据传递的参数来执行相应的操作，并将结果传递给对应的JSP页面进行展示。在doPost方法中，直接调用doGet方法来处理请求。