Controller V5 -1

누구는 v4, 누구는 v3로 개발하고 싶으면 어떡하지?

 

 

1. Adapter 패턴

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• 지금까지 우리가 개발한 프론트 컨트롤러는 한가지 방식의 컨트롤러 인터페이스만 사용할 수 있다.
• ControllerV3 , ControllerV4 는 완전히 다른 인터페이스이다. 
• 따라서 호환이 불가능하다. 
• 마치 v3는 110v이고, v4는 220v 전기 콘센트 같은 것이다. 
• 이럴 때 사용하는 것이 바로 어댑터이다.
• 어댑터 패턴을 사용해서 프론트 컨트롤러가 다양한 방식의 컨트롤러를 처리할 수 있도록 변경해보자.

 

2. V5 구조

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• 핸들러 어댑터: 
  • 중간에 어댑터 역할을 하는 어댑터가 추가되었는데 이름이 핸들러 어댑터이다. 
  • 여기서 어댑터 역할을 해주는 덕분에 다양한 종류의 컨트롤러를 호출할 수 있다.
• 핸들러: 
  • 컨트롤러의 이름을 더 넓은 범위인 핸들러로 변경했다. 그 이유는 이제 어댑터가 있기 때문에 꼭
  • 컨트롤러의 개념 뿐만 아니라 어떠한 것이든 해당하는 종류의 어댑터만 있으면 다 처리할 수 있기 때문이다.

 

3. MyHandlerAdapter

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• boolean supports(Object handler)
  
  • handler = controller
  • Adapter가 해당 Controller를 처리할 수 있는지 판단.
• ModelView handle(request, response, handler)
  • controller에서 Adapter를 호출하고, ModelView를 반환
  • 만약 Controller가 ModelView를 반환하지 못하면 직접 생성해허라도 return해야함
  • Adatpter를 통해 Controller가 호출됨.

public interface MyHandlerAdapter {

    boolean supports(Object handler);

    ModelView handle(HttpServletRequest request, HttpServletResponse response, Object handler) throws ServletException, IOException;
}

 

 

4. ControllerV3HandlerAdapter

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• support : ContorllerV3 처리 가능?
• handle : controller의 process처리하여 return된 ModelView객체 반환 -> V3

/**
 * support V3
 */
public class ControllerV3HandlerAdapter implements MyHandlerAdapter {

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

    }

    @Override
    public ModelView handle(HttpServletRequest request, HttpServletResponse response, Object handler) throws ServletException, IOException {

        ControllerV3 controller = (ControllerV3) handler;

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

        ModelView mv = controller.process(paramMap);

        return mv;
    }

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

 

5. FrontControllerV5

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• HttpServlerRequest정보를 가지고 handler 가져옴.
• handler 커버 가능한 Adapter 가져옴.
• Adapter에서 handle()을 실행하여 controller의 process() 실행하여 ModelView return받음
• ModelView에서 viewName꺼냄
• viewName을 가지고 MyView객체 생성.
• MyView의 render()에 model, request, response 넘겨서 HTML 응답 ㄱㄱ

@WebServlet(name = "FrontControllerServletV5", urlPatterns = "/front-controller/v5/*")
public class FrontControllerServletV5 extends HttpServlet {

    private final Map<String, Object> handlerMappingMap = new HashMap<>();
    private final List<MyHandlerAdapter> handlerAdapters = new ArrayList<>();

    //v5에서 v3지원
    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());
    }

    private void initHandlerAdapters() {
        handlerAdapters.add(new ControllerV3HandlerAdapter());
    }


    @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);

        //adapter의 handle이 controller의 process 호출해줌.
        ModelView mv = adapter.handle(request, response, handler);

        String viewName = mv.getViewName();
        MyView view = viewResolver(viewName);

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

    }

    private Object getHandler(HttpServletRequest request) {
        String requestURI = request.getRequestURI();
        Object handler = handlerMappingMap.get(requestURI);
        return handler;
    }

    private MyHandlerAdapter getHandlerAdapter(Object handler) {
        for (MyHandlerAdapter adapter : handlerAdapters) {
            if(adapter.supports(handler)){
             return adapter;
            }
        }
        throw new IllegalArgumentException("handler adapter를 찾을 수 없음. handler = " + handler);
    }

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

}

 

 

6.GitHub : 210911 FrontController V5-1

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GitHub - bsh6463/MVC1