8장

src/main/java/core/mvc/Controller.java

@@ -4,5 +4,5 @@
 import javax.servlet.http.HttpServletResponse;
 
 public interface Controller {
-    String execute(HttpServletRequest req, HttpServletResponse resp) throws Exception;
+    ModelAndView execute(HttpServletRequest req, HttpServletResponse resp) throws Exception;
 }

src/main/java/core/mvc/DispatcherServlet.java

@@ -1,56 +1,40 @@
 package core.mvc;
 
-import java.io.IOException;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
-import javax.servlet.RequestDispatcher;
 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 org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
-
 @WebServlet(name = "dispatcher", urlPatterns = "/", loadOnStartup = 1)
 public class DispatcherServlet extends HttpServlet {
     private static final long serialVersionUID = 1L;
     private static final Logger logger = LoggerFactory.getLogger(DispatcherServlet.class);
-    private static final String DEFAULT_REDIRECT_PREFIX = "redirect:";
 
     private RequestMapping rm;
 
     @Override
-    public void init() throws ServletException {
+    public void init() {
         rm = new RequestMapping();
         rm.initMapping();
     }
 
     @Override
-    protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
+    protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException {
         String requestUri = req.getRequestURI();
         logger.debug("Method : {}, Request URI : {}", req.getMethod(), requestUri);
 
         Controller controller = rm.findController(requestUri);
         try {
-            String viewName = controller.execute(req, resp);
-            if (viewName != null) {
-                move(viewName, req, resp);
-            }
+            ModelAndView modelAndView = controller.execute(req, resp);
+            View view = modelAndView.getView();
+            view.render(modelAndView.getModel(), req, resp);
         } catch (Throwable e) {
-            logger.error("Exception : {}", e);
+            logger.error("Exception: ", e);
             throw new ServletException(e.getMessage());
         }
     }
-
-    private void move(String viewName, HttpServletRequest req, HttpServletResponse resp)
-            throws ServletException, IOException {
-        if (viewName.startsWith(DEFAULT_REDIRECT_PREFIX)) {
-            resp.sendRedirect(viewName.substring(DEFAULT_REDIRECT_PREFIX.length()));
-            return;
-        }
-
-        RequestDispatcher rd = req.getRequestDispatcher(viewName);
-        rd.forward(req, resp);
-    }
 }

src/main/java/core/mvc/ForwardController.java

@@ -1,20 +1,23 @@
 package core.mvc;
 
+import next.controller.AbstractController;
+
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
 
-public class ForwardController implements Controller {
-    private String forwardUrl;
+public class ForwardController extends AbstractController {
+    private final String forwardUrl;
 
     public ForwardController(String forwardUrl) {
         this.forwardUrl = forwardUrl;
+        // TODO: null 체크를 생성자 첫 줄에서 하는 건 어떨까? + Objects.requireNonNull()
         if (forwardUrl == null) {
             throw new NullPointerException("forwardUrl is null. 이동할 URL을 입력하세요.");
         }
     }
 
     @Override
-    public String execute(HttpServletRequest req, HttpServletResponse resp) throws Exception {
-        return forwardUrl;
+    public ModelAndView execute(HttpServletRequest req, HttpServletResponse resp) {
+        return jspView(forwardUrl);
     }
 }

src/main/java/core/mvc/JsonView.java

@@ -0,0 +1,31 @@
+package core.mvc;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+import java.io.PrintWriter;
+import java.util.Enumeration;
+import java.util.HashMap;
+import java.util.Map;
+
+public class JsonView implements View {
+
+	@Override
+	public void render(final Map<String, ?> model, final HttpServletRequest request, final HttpServletResponse response) throws Exception {
+		ObjectMapper objectMapper = new ObjectMapper();
+		response.setContentType("application/json;charset=UTF-8");
+		PrintWriter writer = response.getWriter();
+		writer.print(objectMapper.writeValueAsString(model));
+	}
+
+	private Map<String, Object> createModelFromRequest(final HttpServletRequest request) {
+		Map<String, Object> models = new HashMap<>();
+		Enumeration<String> attributeNames = request.getAttributeNames();
+		while (attributeNames.hasMoreElements()) {
+			String name = attributeNames.nextElement();
+			models.put(name, request.getAttribute(name));
+		}
+		return models;
+	}
+}

src/main/java/core/mvc/JspView.java

@@ -0,0 +1,36 @@
+package core.mvc;
+
+import javax.servlet.RequestDispatcher;
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+import java.util.Map;
+import java.util.Objects;
+import java.util.Set;
+
+public class JspView implements View {
+
+	private static final String DEFAULT_REDIRECT_PREFIX = "redirect:";
+
+	private final String viewName;
+
+	public JspView(final String viewName) {
+		Objects.requireNonNull(viewName, "viewName is null.");
+		this.viewName = viewName;
+	}
+
+	@Override
+	public void render(final Map<String, ?> model, final HttpServletRequest request, final HttpServletResponse response) throws Exception {
+		if (viewName.startsWith(DEFAULT_REDIRECT_PREFIX)) {
+			response.sendRedirect(viewName.substring(DEFAULT_REDIRECT_PREFIX.length()));
+			return;
+		}
+
+		Set<String> keys = model.keySet();
+		for (String key : keys) {
+			request.setAttribute(key, model.get(key));
+		}
+
+		RequestDispatcher rd = request.getRequestDispatcher(viewName);
+		rd.forward(request, response);
+	}
+}

src/main/java/core/mvc/ModelAndView.java

@@ -0,0 +1,27 @@
+package core.mvc;
+
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.Map;
+
+public class ModelAndView {
+	private final View view;
+	private final Map<String, Object> model = new HashMap<>();
+
+	public ModelAndView(final View view) {
+		this.view = view;
+	}
+
+	public ModelAndView addObject(final String attributeName, final Object attributeValue) {
+		model.put(attributeName, attributeValue);
+		return this;
+	}
+
+	public View getView() {
+		return view;
+	}
+
+	public Map<String, Object> getModel() {
+		return Collections.unmodifiableMap(model);
+	}
+}

src/main/java/core/mvc/View.java

@@ -0,0 +1,9 @@
+package core.mvc;
+
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+import java.util.Map;
+
+public interface View {
+	void render(Map<String, ?> model, HttpServletRequest request, HttpServletResponse response) throws Exception;
+}

src/main/java/next/controller/AbstractController.java

@@ -0,0 +1,16 @@
+package next.controller;
+
+import core.mvc.Controller;
+import core.mvc.JsonView;
+import core.mvc.JspView;
+import core.mvc.ModelAndView;
+
+public abstract class AbstractController implements Controller {
+	protected ModelAndView jspView(String forwardUrl) {
+		return new ModelAndView(new JspView(forwardUrl));
+	}
+
+	protected ModelAndView jsonView() {
+		return new ModelAndView(new JsonView());
+	}
+}

src/main/java/next/controller/HomeController.java

@@ -1,16 +1,18 @@
 package next.controller;
 
+import core.mvc.ModelAndView;
+import next.dao.QuestionDao;
+
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
 
-import core.mvc.Controller;
-import next.dao.QuestionDao;
+public class HomeController extends AbstractController {
 
-public class HomeController implements Controller {
     @Override
-    public String execute(HttpServletRequest req, HttpServletResponse resp) throws Exception {
+    public ModelAndView execute(HttpServletRequest req, HttpServletResponse resp) {
         QuestionDao questionDao = new QuestionDao();
         req.setAttribute("questions", questionDao.findAll());
-        return "home.jsp";
+        return jspView("home.jsp")
+                .addObject("questions", questionDao.findAll());
     }
 }

src/main/java/next/controller/qna/AddAnswerController.java

@@ -1,34 +1,28 @@
 package next.controller.qna;
 
-import java.io.PrintWriter;
-
-import javax.servlet.http.HttpServletRequest;
-import javax.servlet.http.HttpServletResponse;
-
+import core.mvc.ModelAndView;
+import next.controller.AbstractController;
+import next.dao.AnswerDao;
+import next.model.Answer;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-import com.fasterxml.jackson.databind.ObjectMapper;
-
-import core.mvc.Controller;
-import next.dao.AnswerDao;
-import next.model.Answer;
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
 
-public class AddAnswerController implements Controller {
+public class AddAnswerController extends AbstractController {
     private static final Logger log = LoggerFactory.getLogger(AddAnswerController.class);
 
     @Override
-    public String execute(HttpServletRequest req, HttpServletResponse resp) throws Exception {
+    public ModelAndView execute(HttpServletRequest req, HttpServletResponse resp) {
+        // TODO: Answer에 Builder 패턴 적용, 아래에서 사용
         Answer answer = new Answer(req.getParameter("writer"), req.getParameter("contents"),
                 Long.parseLong(req.getParameter("questionId")));
         log.debug("answer : {}", answer);
 
         AnswerDao answerDao = new AnswerDao();
         Answer savedAnswer = answerDao.insert(answer);
-        ObjectMapper mapper = new ObjectMapper();
-        resp.setContentType("application/json;charset=UTF-8");
-        PrintWriter out = resp.getWriter();
-        out.print(mapper.writeValueAsString(savedAnswer));
-        return null;
+        return jsonView()
+                .addObject("answer", savedAnswer);
     }
 }

src/main/java/next/controller/qna/DeleteAnswerController.java

@@ -1,28 +1,24 @@
 package next.controller.qna;
 
-import java.io.PrintWriter;
+import core.mvc.ModelAndView;
+import next.controller.AbstractController;
+import next.dao.AnswerDao;
+import next.model.Result;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
 
-import com.fasterxml.jackson.databind.ObjectMapper;
+public class DeleteAnswerController extends AbstractController {
+    private static final Logger log = LoggerFactory.getLogger(DeleteAnswerController.class);
 
-import core.mvc.Controller;
-import next.dao.AnswerDao;
-import next.model.Result;
-
-public class DeleteAnswerController implements Controller {
     @Override
-    public String execute(HttpServletRequest req, HttpServletResponse resp) throws Exception {
+    public ModelAndView execute(HttpServletRequest req, HttpServletResponse resp) {
         Long answerId = Long.parseLong(req.getParameter("answerId"));
         AnswerDao answerDao = new AnswerDao();
-
         answerDao.delete(answerId);
-
-        ObjectMapper mapper = new ObjectMapper();
-        resp.setContentType("application/json;charset=UTF-8");
-        PrintWriter out = resp.getWriter();
-        out.print(mapper.writeValueAsString(Result.ok()));
-        return null;
+        return jsonView()
+                .addObject("result", Result.ok());
     }
 }

src/main/java/next/controller/qna/ShowController.java

@@ -1,20 +1,22 @@
 package next.controller.qna;
 
+import core.mvc.ModelAndView;
+import next.controller.AbstractController;
+import next.dao.AnswerDao;
+import next.dao.QuestionDao;
+
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
 
-import core.mvc.Controller;
-import next.dao.AnswerDao;
-import next.dao.QuestionDao;
+public class ShowController extends AbstractController {
 
-public class ShowController implements Controller {
     @Override
-    public String execute(HttpServletRequest req, HttpServletResponse resp) throws Exception {
-        Long questionId = Long.parseLong(req.getParameter("questionId"));
+    public ModelAndView execute(HttpServletRequest req, HttpServletResponse resp) {
+        long questionId = Long.parseLong(req.getParameter("questionId"));
         QuestionDao questionDao = new QuestionDao();
         AnswerDao answerDao = new AnswerDao();
-        req.setAttribute("question", questionDao.findById(questionId));
-        req.setAttribute("answers", answerDao.findAllByQuestionId(questionId));
-        return "/qna/show.jsp";
+        return jspView("/qna/show.jsp")
+                .addObject("question", questionDao.findById(questionId))
+                .addObject("answers", answerDao.findAllByQuestionId(questionId));
     }
 }