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// simple tutorial i followed:
// https://www.baeldung.com/mvc-servlet-jsp

// filename: Student (I renamed this to Student.java)

public class Student {
    // Student is the Model Layer (other Model Layer is StudentService) of the MVC Pattern
    private int id;
    private String firstName;
    private String lastName;

    // constructors, getters and setters go here
}

// filename: StudentService (I reanamed this to StudentService.java)

public class StudentService {
    // StudentService is the Model Layer (other Model Layer is Student) of the MVC Pattern
    public Optional<Student> getStudent(int id){
        switch(id) {
            case 1:
                return Optional.of(new Student(1, "John", "Doe"));
            case 2:
                return Optional.of(new Student(2, "Jane", "Goodall"));
            case 3:
                return Optional.of(new Student(3, "Max", "Born"));
            default:
                return Optional.empty();
        }
    }
}

// filename: StudentServlet (I renamed to StudentServlet.java)

@WebServlet(
    name = "StudentServlet",
    urlPatterns = "/student-record")

public class StudentServlet extends HttpServlet {
    // StudentServlet is our Controller Layer of the MVC pattern
    private 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);
        }
    }


// filename: student-record.jsp

<html>
    <head>
        <title>Student Record</title>
    </head>
    <body>
        <%
            if (request.getAttribute("studentRecord") != null) {
                Student student = (Student) request.getAttribute("studentRecord");
        %>

        <h1>Student Record</h1>
        <div>ID: <%= student.getId()%></div>
        <div> First Name: <%= student.getFirstName()%></div>
        <div> Last Name: <%= student.getLastName()%></div>

        <%
            } else {
        %>

        <h1>No Student Record Found.</h1>

        <% } %>
    </body>
</html>