[2023 동계 모각코] 4회차 회고

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Java Servlet 프로그래밍 1차

• 학생 관리 프로그램 MVC 패턴으로 구성하기

결과

// Domain

@Getter @Setter
public class Student {
    //아이디
    private  String id;
    //이름
    private  String name;
    //성별
    private  Gender gender;
    //나이
    private  int age;
    //생성일
    private LocalDateTime createdAt;

}

// Repository

public interface StudentRepository {

    //학생-등록
    void save(Student student);
    //학생-수정
    void update(Student student);
    //학생-삭제
    void deleteById(String id);
    //학생-조회_by id
    Student getStudentById(String id);
    //학생-리스트
    List<Student> getStudents();
    //학생-아이디 존재여부
    boolean existById(String id);

}

// Repository 구현

public class MapStudentRepository implements StudentRepository {

    private final Map<String, Student> studentsMap = new ConcurrentHashMap<>();

    @Override
    public void save(Student student) {
        studentsMap.put(student.getId(), student);
    }

    @Override
    public void update(Student student) {
        if (studentsMap.containsKey(student.getId())) {
            studentsMap.put(student.getId(), student);
        } else {
            throw new IllegalArgumentException();
        }
    }

    @Override
    public void deleteById(String id) {
        studentsMap.remove(id);
    }

    @Override
    public Student getStudentById(String id) {
        return studentsMap.get(id);
    }

    @Override
    public List<Student> getStudents() {
        return new ArrayList<>(studentsMap.values());
    }

    @Override
    public boolean existById(String id) {
        return studentsMap.containsKey(id);
    }
}

// Servlet 예시 (StudnetUpdateServlet)

@WebServlet(name = "studentUpdateServlet", urlPatterns = "/student/update")
public class StudentUpdateServlet extends HttpServlet {
    private StudentRepository studentRepository;

    @Override
    public void init(ServletConfig config) {
        studentRepository = (StudentRepository) config.getServletContext().getAttribute("studentRepository");
    }

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        // id 를 받았으니 해당 아이디로 학생을 조회해 jsp 로 넘김
        String id = req.getParameter("id");
        Student student = studentRepository.getStudentById(id);

        req.setAttribute("student", student);

//        RequestDispatcher rd = req.getRequestDispatcher("/student/register");
//        rd.forward(req, resp);

        req.setAttribute("view", "/student/register");
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) {
        try {
            String id = req.getParameter("id");
            String name = req.getParameter("name");
            Gender gender = Gender.valueOf(req.getParameter("gender"));
            int age = Integer.parseInt(req.getParameter("age"));
            req.getParameter("age");

            if (id == null || name == null) {
                log.error("파라미터에 null 이 있음");
                resp.sendRedirect("/student/register.jsp");
                return;
            }

            // 기존 학생 정보 id로 가져오기
            Student existingStudent = studentRepository.getStudentById(id);
            existingStudent.setName(name);
            existingStudent.setGender(gender);
            existingStudent.setAge(age);

            studentRepository.update(existingStudent);

//            resp.sendRedirect("/student/view?id=" + id);
            req.setAttribute("view","redirect:/student/view.do?id=" + existingStudent.getId());
            log.info("update: front 로 가서 처리");

        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }
}

소감

스프링으로만 간단하게 해봤어서 쉽게 했었는데 스프링 없이 Servlet 으로 하려니 어렵긴 하다...