[스프링부트] 12. MVC 프레임워크(리다이렉션)

Mar 19, 2025

Contents


package org.example.demo10;

import jakarta.servlet.ServletConfig;
import jakarta.servlet.ServletException;
import jakarta.servlet.annotation.WebServlet;
import jakarta.servlet.http.HttpServlet;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;
import org.example.demo10.core.ComponentScan;
import org.example.demo10.core.RequestMapping;
import org.example.demo10.core.ViewResolver;

import java.io.IOException;
import java.lang.reflect.Method;
import java.util.Set;

@WebServlet("*.do")
public class DispatcherServlet extends HttpServlet {

    private Set<Object> controllers;

    @Override
    public void init(ServletConfig config) throws ServletException {
        // 1. 컴포넌트 스캔
        ComponentScan componentScan = new ComponentScan(config.getServletContext());
        controllers = componentScan.scanClass("org.example.demo10.controller");
        //System.out.println(controllers.size());
    }

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        // localhost:8080/user.do?path=join
        String path = req.getParameter("path");

        // 2. 라우팅
        String templatePath = route(path);

        // 3. 리다이렉션
        if (templatePath.contains("redirect:")) {
            String redirectPath = templatePath.replace("redirect:", "");
//            resp.setStatus(302);
//            resp.setHeader("Location", "?path=" + redirectPath);
            resp.sendRedirect("?path=" + redirectPath); 
            // 이 코드는 위에 두 줄을 내장하고 있음 302세팅
            return;
        }

        // 4. 이동
        if (templatePath == null) {
            resp.setStatus(404);
            resp.getWriter().println("<h1>404 Not Found</h1>");
        } else {
            req.getRequestDispatcher(ViewResolver.viewName(templatePath)).forward(req, resp);
        }


    }

    private String route(String path) {
        for (Object instance : controllers) {
            Method[] methods = instance.getClass().getMethods();

            for (Method method : methods) {
                RequestMapping rm = method.getAnnotation(RequestMapping.class);

                if (rm == null) continue; // 다음 for문으로 바로 넘어감

                if (rm.value().equals(path)) {
                    try {
                        return (String) method.invoke(instance);

                    } catch (Exception e) {
                        throw new RuntimeException(e);
                    }
                }
            }
        }
        return null;
    }
}


package org.example.demo10.controller;

import org.example.demo10.core.Controller;
import org.example.demo10.core.RequestMapping;

@Controller
public class UserController {

    @RequestMapping("join")
    public String join() {
        System.out.println("UserController join");
        return "join";
    }

    @RequestMapping("login")
    public String login() {
        System.out.println("UserController login");
        return "redirect:home";
    }
}


package org.example.demo10.controller;

import org.example.demo10.core.Controller;
import org.example.demo10.core.RequestMapping;

@Controller
public class BoardController {

    @RequestMapping("home")
    public String home() {
        return "home";
    }
}


<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
</head>
<body>
<h1>home page</h1>
</body>
</html>


<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
</head>
<body>
<h1>join page</h1>
</body>
</html>


<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
</head>
<body>
<h1>login page</h1>
</body>
</html>

💡

리다이렉트와 포워딩을 지원 (redirect:home)

Spring MVC - 간단한 회원가입 및 페이지 이동 예제

프로젝트 생성

BoardController


package org.example.hello.controller;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.GetMapping;

@Controller
public class BoardController {

    // localhost:8080/detail (GET) detail.mustache
    @GetMapping("/detail")
    public String detail() {
        return "detail";
    }

    // localhost:8080/home
    @GetMapping("/home")
    public String home() {
        return "home";
    }
}

UserController


package org.example.hello.controller;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PostMapping;

@Controller
public class UserController {

    // localhost:8080/join
    // body : username=ssar
    // header : Content-Type : application/x-www-form-urlencoded
    // 줄게 -> 회원가입 정보
    @PostMapping("/join")
    public String join(String username) {
        // 1. DB insert
        System.out.println("username : " + username);

        // 2. 응답
        return "redirect:/home";
    }

    // 줘 -> 회원가입 페이지
    @GetMapping("/join-form")
    public String joinForm() {
        return "join-form";
    }
}


<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<h1>회원가입 페이지 - 폼태그, 인풋</h1>
<form action="/join" method="post">
    <input type="text" name="username" placeholder="Enter username">
    <button type="submit">회원가입</button>
</form>
</body>
</html>


<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<h1>홈 페이지</h1>
</body>
</html>


<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<h1>디테일 페이지 입니다.</h1>
</body>
</html>

💡

회원가입 페이지 (join-form)

/join-form으로 GET 요청을 보내면 join-form.html을 보여줌.

HTML에는 input과 submit 버튼이 있음.

사용자가 입력하고 "회원가입" 버튼을 누르면 /join으로 POST 요청이 감.

회원가입 요청 (join)

사용자가 username을 입력하면 /join으로 요청을 보냄.

join(String username) 메서드가 실행됨.

System.out.println()을 통해서 입력값을 출력함.

완료되면 redirect:/home으로 이동해서 홈 화면을 보여줌.

홈 화면 (home)

/home으로 GET 요청을 보내면 home.html이 보여짐.

디테일 페이지 (detail)

/detail로 요청을 보내면 detail.html을 보여줌.

See more posts

[스프링부트] 12. MVC 프레임워크(리다이렉션)

Spring MVC - 간단한 회원가입 및 페이지 이동 예제

프로젝트 생성

BoardController

UserController

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