Controller V4

항상 ModelView객체를 생성하고 반환해야 하는 부분이 귀찮음..

 

1. V4 구조

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• 컨트롤러가 ModelView 를 반환하지 않고, ViewName 만 반환한다

 

2. Controllerr V4

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• FrontController가 model, paramMap을 만들어서 controller에 전달.

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

}

 

3. FrontController V4

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@WebServlet(name = "FrontControllerServletV4", urlPatterns = "/front-controller/v4/*")
public class FrontControllerServletV4 extends HttpServlet {

    private Map<String, ControllerV4> controllerMap = new HashMap<>();

    public FrontControllerServletV4() {

        controllerMap.put("/front-controller/v4/members/new-form", new MemberFormControllerV4());
        controllerMap.put("/front-controller/v4/members/save", new MemberSaveControllerV4());
        controllerMap.put("/front-controller/v4/members", new MemberListControllerV4());
    }

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

        String requestURI = request.getRequestURI();

        ControllerV4 controller = controllerMap.get(requestURI);
        if(controller == null){
            response.setStatus(HttpServletResponse.SC_NOT_FOUND);
            return;
        }

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

        MyView view = viewResolver(viewName);

        //모델은 render에 넘겨줘야함.
        view.render(model, request,response);


    }

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

    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;
    }
}

 

4. MemberFromController V4

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public class MemberFormControllerV4 implements ControllerV4 {


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

 

5. MemberSaveController V4

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public class MemberSaveControllerV4 implements ControllerV4 {

    private MemberRepository memberRepository = MemberRepository.getInstance();

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

        Member member = new Member(username, age);

        memberRepository.save(member);

        model.put("member", member);

        return "save-result";
    }
}

• model.put("member", member)
• 모델이 파라미터로 전달되기 때문에, 모델을 직접 생성하지 않아도 된다.

 

6. MemberListController v4

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public class MemberListControllerV4 implements ControllerV4 {

    private MemberRepository memberRepository = MemberRepository.getInstance();

    @Override
    public String process(Map<String, String> paramMap, Map<String, Object> model) {
        List<Member> members = memberRepository.findAll();

        model.put("members",members);

        return "members";
    }
}

 

 

7. 정리

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• 이번 버전의 컨트롤러는 매우 단순하고 실용적이다. 
• 기존 구조에서 모델을 파라미터로 넘기고, 뷰의 논리 이름을 반환한다는 작은 아이디어를 적용했을 뿐인데, 
• 컨트롤러를 구현하는 개발자 입장에서 보면 이제 군더더기 없는 코드를 작성할 수 있다.
• 또한 중요한 사실은 여기까지 한번에 온 것이 아니라는 점이다. 
• 프레임워크가 점진적으로 발전하는 과정속에서 이런 방법도 찾을 수 있었다.

 

 

8. GitHub : 210911 FrontController V4

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GitHub - bsh6463/MVC1