[스프링] MVC 프레임워크

MVC 프레임워크

프론트 컨트롤러 패턴

• 특징
  • 프론트 컨트롤러 서블릿 하나로 클라이언트의 요청 받음
  • 프론트 컨트롤러가 요청에 맞는 컨트롤러 찾아 호출
  • 공통 처리
  • 프론트 컨트롤러 제외한 나머지 컨트롤러 서블릿 사용x

프론트 컨트롤러 도입1

• 컨트롤러 인터페이스-> - 회원 등록 컨트롤러, 회원 저장 컨트롤러, 회원 목록 컨트롤러

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

• 프론트 컨트롤러

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

View 분리2

• MyView

  private String viewPath;
  
  public MyView(String viewPath) {
  this.viewPath = viewPath;
  }
  public void render(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
  RequestDispatcher dispatcher = request.getRequestDispatcher(viewPath);
  dispatcher.forward(request, response);
  }

• 컨트롤러 인터페이스

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

  구현

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

• 프론트 컨트롤러

  MyView view = controller.process(request, response);
  view.render(request, response);

Model 추가3

• 서블릿 종속성 제거: 요청 파라미터 정보-> 자바의 Map, request 객체-> 별도의 Model 객체
• 뷰 이름 중복 제거: 컨트롤러는 뷰의 논리 이름 반환

• ModelView

  private String viewName;
  private Map<String, Object> model = new HashMap<>();
  
  public ModelView(String viewName) {
  this.viewName = viewName;
  }

• 컨트롤러 인터페이스

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

  구현

  @Override
  public ModelView process(Map<String, String> paramMap) {
    //paramMap: request통해 받은 파라미터 정보
    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;
  }

• 프론트 컨트롤러

  //createParamMap: request통해 받은 파라미터 정보 담기
  Map<String, String> paramMap = createParamMap(request); 
  ModelView mv = controller.process(paramMap);
  String viewName = mv.getViewName();
  //viewResolver: 논리 뷰 이름(members)-> 물리 뷰 경로로 변경(/WEB-INF/views/members.jsp)
  MyView view = viewResolver(viewName);
  view.render(mv.getModel(), request, response);

• MyView

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

단순하고 실용적인 컨트롤러4

• 컨트롤러 인터페이스

  //model 만들지 않고 사용하면된다, String 반환
  String process(Map<String, String> paramMap, Map<String, Object> model);

  구현

  model.put("member", member);
  return "save-result";

• 프론트 컨트롤러

  모델 객체 프론트 컨트롤러에서 생성해서 넘김
  Map<String, Object> model = new HashMap<>();
  
  //논리 이름 직접 반환
  String viewName = controller.process(paramMap, model);
  

### 유연한 컨트롤러5


- 컨트롤러 인터페이스

//v3
ModelView process(Map<String, String> paramMap);

//v4
String process(Map<String, String> paramMap, Map<String, Object> model);

둘다 사용하려면? 어댑터 패턴


- 어댑터 인터페이스
    ```
    //handler는 컨트롤러
    boolean supports(Object handler);

    //어댑터 통해서 실제 컨트롤러 호출
    ModelView handle(HttpServletRequest request, HttpServletResponse response, Object handler) throws ServletException, IOException;

구현v3

  @Override
   public boolean supports(Object handler) {
      return (handler instanceof ControllerV3);
   }

   @Override
   public ModelView handle(HttpServletRequest request, HttpServletResponse response, Object handler) {
      ControllerV3 controller = (ControllerV3) handler;
      Map<String, String> paramMap = createParamMap(request);
      ModelView mv = controller.process(paramMap);
      return mv;
   }

구현v4

   ControllerV4 controller = (ControllerV4) handler;
   Map<String, String> paramMap = createParamMap(request);
   Map<String, Object> model = new HashMap<>();
   String viewName = controller.process(paramMap, model);

   //형식맞추기
   ModelView mv = new ModelView(viewName);
   mv.setModel(model);

   return mv;

• 프론트 컨트롤러

  private final Map<String, Object> handlerMappingMap = new HashMap<>();
   private final List<MyHandlerAdapter> handlerAdapters = new ArrayList<>();
   public FrontControllerServletV5() {
      initHandlerMappingMap();
      initHandlerAdapters();
   }
   private void initHandlerMappingMap() {
      handlerMappingMap.put("/front-controller/v5/v3/members/new-form", new MemberFormControllerV3());
      handlerMappingMap.put("/front-controller/v5/v3/members/save", new MemberSaveControllerV3());
      handlerMappingMap.put("/front-controller/v5/v3/members", new MemberListControllerV3());
  
      handlerMappingMap.put("/front-controller/v5/v4/members/new-form", new MemberFormControllerV4());
      handlerMappingMap.put("/front-controller/v5/v4/members/save", new MemberSaveControllerV4());
      handlerMappingMap.put("/front-controller/v5/v4/members", newMemberListControllerV4());
   }
   private void initHandlerAdapters() {
      handlerAdapters.add(new ControllerV3HandlerAdapter());
      handlerAdapters.add(new ControllerV4HandlerAdapter());
   }
   @Override
   protected void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
      Object handler = getHandler(request);
      if (handler == null) {
          response.setStatus(HttpServletResponse.SC_NOT_FOUND);
          return;
      }
      MyHandlerAdapter adapter = getHandlerAdapter(handler);
      ModelView mv = adapter.handle(request, response, handler);
      MyView view = viewResolver(mv.getViewName());
      view.render(mv.getModel(), request, response);
   }

링크
https://www.inflearn.com/course/%EC%8A%A4%ED%94%84%EB%A7%81-mvc-1