30. 유용한 컨트롤러 2 - v5

FrontControllerServletV5 에 ControllerV4 기능도 추가해보자

ackage hello.servlet.web.frontcontroller.v5;
import hello.servlet.web.frontcontroller.ModelView;
import hello.servlet.web.frontcontroller.MyView;
import hello.servlet.web.frontcontroller.v3.controller.MemberFormControllerV3;
import hello.servlet.web.frontcontroller.v3.controller.MemberListControllerV3;
import hello.servlet.web.frontcontroller.v3.controller.MemberSaveControllerV3;
import hello.servlet.web.frontcontroller.v5.adapter.ControllerV3HandlerAdapter;
import hello.servlet.web.frontcontroller.v5.adapter.ControllerV4HandlerAdapter;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
@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());
         //V4 추가
         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()); //V4 추가
     }
     
     @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);
     }
     
     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=" + handler);
     }
     
     private MyView viewResolver(String viewName) {
     	return new MyView("/WEB-INF/views/" + viewName + ".jsp");
     }
}

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());
     
     //V4 추가
     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()); //V4 추가
}

핸들러 매핑( handlerMappingMap )에 ControllerV4 를 사용하는 컨트롤러를 추가하고,

해당 컨트롤러를 처리할 수 있는 어댑터인 ControllerV4HandlerAdapter 도 추가하자.

 

---

ControllerV4HandlerAdapter

package hello.servlet.web.frontcontroller.v5.adapter;
import hello.servlet.web.frontcontroller.ModelView;
import hello.servlet.web.frontcontroller.v4.ControllerV4;
import hello.servlet.web.frontcontroller.v5.MyHandlerAdapter;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.util.HashMap;
import java.util.Map;

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) {
         ControllerV4 controller = (ControllerV4) handler;
         Map<String, String> paramMap = createParamMap(request);
         Map<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;
     }
}

하나씩 분석해보자

 

 

public boolean supports(Object handler) {
 return (handler instanceof ControllerV4);
}

handler 가 ControllerV4 인 경우에만 처리하는 어댑터이다

 

 

실행 로직

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

handler를 ControllerV4로 케스팅 하고, paramMap, model을 만들어서 해당 컨트롤러를 호출한다. 그리고 viewName을 반환 받는다.

 

 

어댑터 변환

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

return mv;

어댑터에서 이 부분이 단순하지만 중요한 부분이다.

 

어댑터가 호출하는 ControllerV4 는 뷰의 이름을 반환한다.

그런데 어댑터는 뷰의 이름이 아니라 ModelView 를 만들어서 반환해야 한다.

여기서 어댑터가 꼭 필요한 이유가 나온다.

ControllerV4 는 뷰의 이름을 반환했지만, 어댑터는 이것을 ModelView로 만들어서 형식을 맞추어 반환한다.

마치 110v 전기 콘센트를 220v 전기 콘센트로 변경하듯이!

 

---

어댑터와 ControllerV4

public interface ControllerV4 {
 	String process(Map<String, String> paramMap, Map<String, Object> model);
}

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

 

 

실행

- 등록: http://localhost:8080/front-controller/v5/v4/members/new-form

- 목록: http://localhost:8080/front-controller/v5/v4/members