영한킴: spring MVC (1) : 강의 노트 : 스프링 만들기 V1 to V5

이 포스트는 강의 내용에 관한 노트나 필자가 코딩한 것을 기록했습니다

MVC Version 1

FrontController 패턴으로 전환
- FrontController 생성
- 매핑정보를 조회하기 위한 ControllMap 생성

아래처럼 코드를 구성해보았는데 잘 작동한다 !

protected void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    System.out.println("FrontControllerServletV1.service");

    String requestURI = request.getRequestURI();

    ControllerV1 whichController =
        controllerMap
            .entrySet()
            .stream()
            .filter(entry -> entry.getKey().equals(requestURI))
            .findFirst()
            .orElseThrow(()-> new IllegalArgumentException("해당되는 URI가 없습니다"))
            .getValue();

    whichController.process(request, response);

  }

하지만 영한 킴님의 간결한 코드에.. 난 울어버렸다 ..

  @Override
  protected void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    System.out.println("FrontControllerServletV1.service");

    String requestURI = request.getRequestURI();

    ControllerV1 controller = controllerMap.get(requestURI);
    if (controller == null) {
      response.setStatus(HttpServletResponse.SC_NOT_FOUND);
      return;
    }
    controller.process(request, response);
  }

전체 코드 (변화된 부분 위주)

@WebServlet(name = "frontControllerServletV1", urlPatterns = "/front-controller/v1/*")
public class FrontControllerServletV1 extends HttpServlet {

  private Map<String, ControllerV1> controllerMap = new HashMap<>();

  public FrontControllerServletV1() {
    controllerMap.put("/front-controller/v1/members/new-form", new MemberFormControllerV1());
    controllerMap.put("/front-controller/v1/members/save", new MemberSaveControllerV1());
    controllerMap.put("/front-controller/v1/members", new MemberListControllerV1());
  }

  @Override
  protected void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    System.out.println("FrontControllerServletV1.service");

    String requestURI = request.getRequestURI();

    ControllerV1 controller = controllerMap.get(requestURI);
    if (controller == null) {
      response.setStatus(HttpServletResponse.SC_NOT_FOUND);
      return;
    }
    controller.process(request, response);
  }
}

public interface ControllerV1 {

  void process(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException;

}

MVC Version 2

View 분리
- MyView 생성
- 이제 Controller에서 MyView를 반환한다
- FrontController에서는 이것을 렌더링(JSP 호출)

내가 리펙터링 한 것

protected void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    System.out.println("FrontControllerServletV1.service");

    String requestURI = request.getRequestURI();

    ControllerV1 controller = controllerMap.get(requestURI);
    if (controller == null) {
      response.setStatus(HttpServletResponse.SC_NOT_FOUND);
      return;
    }
    controller.process(request, response);

    String[] strings = requestURI.split("/");

    Arrays.stream(strings).iterator().forEachRemaining(s -> System.out.println("s = " + s));

    String lastURI = strings[strings.length - 1];
    System.out.println("lastURI = " + lastURI);
    if(lastURI.equals("save")) {
      lastURI = "save-result";
    }
    RequestDispatcher dispatcher = request.getRequestDispatcher("/WEB-INF/views/" + lastURI+".jsp");
    dispatcher.forward(request, response);
  }

아래는 영한킴님의 코드

public interface ControllerV2 {

  MyView process(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException;

}

  @Override
  protected void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

    String requestURI = request.getRequestURI();

    ControllerV2 controller = controllerMap.get(requestURI);
    if (controller == null) {
      response.setStatus(HttpServletResponse.SC_NOT_FOUND);
      return;
    }
    MyView view = controller.process(request, response);
    view.render(request, response);
  }

public class MemberFormControllerV2 implements ControllerV2 {

  @Override
  public MyView process(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    return new MyView("/WEB-INF/views/new-form.jsp");
  }
}
// MemberServiceControllerV2, MemberListCOntrollerV2 등... 이하 동일

MVC Version 3

Model 분리
- Controller가 HttpServlet에서 완전히 독립할 수 있도록 인자로 전달되는 request, response 제거
이것을 위한 Model 클래스 생성 (request.setAttribute 를 대체하기 위함)
view path를 조립해주는 viewResolver 추가

public interface ControllerV3 {

  ModelView process(Map<String, String> paramMap);

}

public class FrontControllerServletV3 extends HttpServlet {

  ...

  protected void service (...) {

    ...

    // paramMap
    Map<String, String> paramMap = createParamMap(request);

    ModelView mv = controller.process(paramMap);

    String viewName = mv.getViewName(); // 논리 이름 new-form

    MyView view = viewReolver(viewName);

    view.render(mv.getModel(), request, response);

  }

  private MyView viewReolver(String viewName) {
    return new MyView("/WEB-INF/views/" + viewName + ".jsp");
  }

  private Map<String, String> createParamMap(HttpServletRequest request) {
    Map<String, String> paramMap = new HashMap<>();
    request
        .getParameterNames()
        .asIterator()
        .forEachRemaining(paramName
            -> paramMap.put(paramName, request.getParameter(paramName)
        ));
    return paramMap;
  }
}

public interface ControllerV3 {
  ModelView process(Map<String, String> paramMap);
}

public class MemberSaveControllerV3 implements ControllerV3 {

  private MemberRepository memberRepository = MemberRepository.getInstance();

  @Override
  public ModelView process(Map<String, String> paramMap) {
    String username = paramMap.get("username");
    int age = Integer.parseInt(paramMap.get("age"));

    Member member = new Member(username, age);
    memberRepository.save(member);

    ModelView mv = new ModelView("save-result");
    mv.getModel().put("member", member);

    return mv;
  }
}

@Getter @Setter
public class ModelView {

  private String viewName;
  private Map<String, Object> model = new HashMap<>();

  public ModelView(String viewName) {
    this.viewName = viewName;
  }

}

public class MyView {

  ...

  public void render(Map<String, Object> model, HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    modelToRequestAttribute(model, request);
    RequestDispatcher dispatcher = request.getRequestDispatcher(viewPath);
    dispatcher.forward(request, response);
  }

  private void modelToRequestAttribute(Map<String, Object> model, HttpServletRequest request) {
    model.forEach((key, value) -> {
      request.setAttribute(key, value);
    });
  }
}

MVC Version 4

Model을 각 컨트롤러가 아닌 Front Controller 에서 생성하게 하자 !

아래는 주 변경 내역이다

public interface ControllerV4 {
/**
* @param paramMap
* @param model
* @return viewName
*/
String process(Map<String, String> paramMap, Map<String, Object> model);
}

public class MemberFormControllerV4 implements ControllerV4 {
  @Override
  public String process(Map<String, String> paramMap, Map<String, Object> model) {
    return "new-form";
  }
}

public class FrontControllerServletV4 ... {
  protected void service(...) {
    ...
    Map<String, Object> model = new HashMap<>(); //추가
    String viewName = controller.process(paramMap, model);
    ...
  }
}

MVC Version 5

process 인자로 V1 ~ V4 .. 혹은 그 이외의 시그니쳐로 이용하고 싶을 때가 있다
이럴 때, 어댑터 패턴을 이용한다 !
이제 Controller는 Adapter를 통해 호출된다 !

MVC Version 1

MVC Version 2

MVC Version 3

MVC Version 4

MVC Version 5

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