26. View 분리 - v2

View 분리 - v2

모든 컨트롤러에서 뷰로 이동하는 부분에 중복이 있고, 깔끔하지 않다.

String viewPath = "/WEB-INF/views/new-form.jsp";
RequestDispatcher dispatcher = request.getRequestDispatcher(viewPath);
dispatcher.forward(request, response);

이 부분을 깔끔하게 분리하기 위해 별도로 뷰를 처리하는 객체를 만들자.

 

 

V2 구조

---

MyView

뷰 객체는 이후 다른 버전에서도 함께 사용하므로 패키지 위치를 frontcontroller 에 두었다.

package hello.servlet.web.frontcontroller;

import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

public class 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);
    }
}

• 이 코드만 봐서는 어떻게 활용하는지 아직 감이 안올 것이다.
• 다음 버전의 컨트롤러 인터페이스를 만들어보자.
• 컨트롤러가 뷰를 반환하는 특징이 있다.

 

---

ControllerV2

package hello.servlet.web.frontcontroller.v2.controller;

import hello.servlet.web.frontcontroller.MyView;
import hello.servlet.web.frontcontroller.v2.ControllerV2;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

public class MemberFormControllerV2 implements ControllerV2 {


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

---

 

MemberFormControllerV2 - 회원 등록 폼

package hello.servlet.web.frontcontroller.v2.controller;

import hello.servlet.web.frontcontroller.MyView;
import hello.servlet.web.frontcontroller.v2.ControllerV2;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

public class MemberFormControllerV2 implements ControllerV2 {


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

• 이제 각 컨트롤러는 복잡한 dispatcher.forward() 를 직접 생성해서 호출하지 않아도 된다.
• 단순히 MyView 객체를 생성하고 거기에 뷰 이름만 넣고 반환하면 된다.
• ControllerV1 을 구현한 클래스와 ControllerV2 를 구현한 클래스를 비교해보면,
  이 부분의 중복이 확실하게 제거된 것을 확인할 수 있다.

---

MemberSaveControllerV2 - 회원 저장

package hello.servlet.web.frontcontroller.v2.controller;

import hello.servlet.domain.member.Member;
import hello.servlet.domain.member.MemberRepository;
import hello.servlet.web.frontcontroller.MyView;
import hello.servlet.web.frontcontroller.v2.ControllerV2;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

public class MemberSaveControllerV2 implements ControllerV2 {

    MemberRepository memberRepository = MemberRepository.getInstance();

    @Override
    public MyView process(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        String username = request.getParameter("username");
        int age = Integer.parseInt(request.getParameter("age"));

        Member member = new Member(username, age);
        System.out.println("member = " + member);
        memberRepository.save(member);

        //Model에 데이터를 보관한다.
        request.setAttribute("member", member);

        return new MyView("/WEB-INF/views/save-result.jsp");
    }
}

---

MemberListControllerV2 - 회원 목록

package hello.servlet.web.frontcontroller.v2.controller;

import hello.servlet.domain.member.Member;
import hello.servlet.domain.member.MemberRepository;
import hello.servlet.web.frontcontroller.MyView;
import hello.servlet.web.frontcontroller.v2.ControllerV2;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.List;

public class MemberListControllerV2 implements ControllerV2 {

    MemberRepository memberRepository = MemberRepository.getInstance();

    @Override
    public MyView process(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        System.out.println("MvcMemberListServlet.service");

        List<Member> members = memberRepository.findAll();
        request.setAttribute("members", members);

        return new MyView("/WEB-INF/views/members.jsp");
    }
}

---

프론트 컨트롤러 V2

package hello.servlet.web.frontcontroller.v2;

import hello.servlet.web.frontcontroller.MyView;
import hello.servlet.web.frontcontroller.v1.ControllerV1;
import hello.servlet.web.frontcontroller.v1.controller.MemberFormControllerV1;
import hello.servlet.web.frontcontroller.v1.controller.MemberListControllerV1;
import hello.servlet.web.frontcontroller.v1.controller.MemberSaveControllerV1;
import hello.servlet.web.frontcontroller.v2.controller.MemberFormControllerV2;
import hello.servlet.web.frontcontroller.v2.controller.MemberListControllerV2;
import hello.servlet.web.frontcontroller.v2.controller.MemberSaveControllerV2;

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.HashMap;
import java.util.Map;

@WebServlet(name = "frontControllerServletV2", urlPatterns = "/font-controller/v2/*")
public class FrontControllerServletV2 extends HttpServlet {

    private Map<String, ControllerV2> controllerV2Map = new HashMap<>();

    public FrontControllerServletV2() {
        controllerV2Map.put("/front-controller/v2/members/new-form", new MemberFormControllerV2());
        controllerV2Map.put("/front-controller/v2/members/save", new MemberSaveControllerV2());
        controllerV2Map.put("/front-controller/v2/members", new MemberListControllerV2());
    }

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

        String requestURI =  request.getRequestURI();

        ControllerV2 controller = controllerV2Map.get(requestURI);
        if (controller == null){
            response.setStatus(HttpServletResponse.SC_NOT_FOUND);
            return;
        }

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

    }
}

• ControllerV2의 반환 타입이 MyView 이므로 프론트 컨트롤러는 컨트롤러의 호출 결과로 MyView 를 반환 받는다.
• 그리고 view.render() 를 호출하면 forward 로직을 수행해서 JSP가 실행된다.

 

 

MyView.render()

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

• 프론트 컨트롤러의 도입으로 MyView 객체의 render() 를 호출하는 부분을 모두 일관되게 처리할 수 있다.
• 각각의 컨트롤러는 MyView 객체를 생성만 해서 반환하면 된다.