[스프링MVC - 1편] MVC 프레임워크 만들기 (4)

유연한 컨트롤러1 - v5

어댑터 패턴

지금까지 우리가 개발한 프론트 컨트롤러는 한가지 방식의 컨트롤러 인터페이스만 사용할 수 있다

ControllerV3, ControllerV4는 완전히 다른 인터페이스이며 호환이 불가능하다

어댑터 패턴을 사용해서 프론트 컨트롤러가 다양한 방식의 컨트롤러를 처리할 수 있도록 변경한다

 

 

V5 구조

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

 

 

1. MyHandlerAdapter

public interface MyHandlerAdapter {
    boolean supports(Object handler);
    ModelView handle(HttpServletRequest request, HttpServletResponse response, Object handler) throws ServletException, IOException;
}

 

 

2. ControllerV3HandlerAdapter

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

 

 

3. FrontControllerServletV5

@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<>();

    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);
        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();
        return handlerMappingMap.get(requestURI);
    }

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

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

 

 

유연한 컨트롤러2- v5

@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<>();

    public FrontControllerServletV5() {
        initHandlerMappingMap();
        initHandlerAdapters();
    }

    private void initHandlerMappingMap() {
        // V3
        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());

        // V4
        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", new MemberListControllerV4());
    }

    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);

        String viewName = mv.getViewName();
        MyView view = viewResolver(viewName);
        view.render(mv.getModel(), request, response);
    }

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

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

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

 

 

ControllerV4HandlerAdapter

public class ControllerV4HandlerAdapter implements MyHandlerAdapter {
    @Override
    public boolean supports(Object handler) {
        return (handler instanceof ControllerV4);
    }

    @Override
    public ModelView handle(HttpServletRequest request, HttpServletResponse response, Object handler) throws ServletException, IOException {
        ControllerV4 controller = (ControllerV4) handler;

        Map<String, String> paramMap = createParamMap(request);
        HashMap<String, Object> model = new HashMap<>();

        String viewName = controller.process(paramMap, model);

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

        return mv;
    }

    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;
    }
}