java-tutorials/javax-servlets/src/main/java/com/baeldung/controller/StudentServlet.java

package com.baeldung.controller;

import com.baeldung.service.StudentService;

import javax.servlet.RequestDispatcher;
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 java.io.IOException;

@WebServlet(name = "StudentServlet", urlPatterns = "/student-record")
public class StudentServlet extends HttpServlet {

    private final StudentService studentService = new StudentService();

    private void processRequest(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        String studentID = request.getParameter("id");
        if (studentID != null) {
            int id = Integer.parseInt(studentID);
            studentService.getStudent(id)
              .ifPresent(s -> request.setAttribute("studentRecord", s));
        }

        RequestDispatcher dispatcher = request.getRequestDispatcher("/WEB-INF/jsp/student-record.jsp");
        dispatcher.forward(request, response);
    }

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

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