[스프링부트] 11. MVC 프레임워크

MVC 프레임워크

DispatcherServlet 코드

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. 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;
    }
}

ViewResolver 코드

package org.example.demo10.core;

public class ViewResolver {
    private static final String prefix = "/WEB-INF/views/";
    private static final String suffix = ".jsp";

    public static String viewName(String filename) {
        return prefix + filename + suffix;
    }
}

ComponentScan 코드

package org.example.demo10.core;

import jakarta.servlet.ServletContext;

import java.io.File;
import java.util.HashSet;
import java.util.Set;

public class ComponentScan {
    private final ServletContext servletContext;

    public ComponentScan(ServletContext servletContext) {
        this.servletContext = servletContext;
    }

    // 클래스를 스캔하는 메소드
    public Set<Object> scanClass(String pkg) {
        Set<Object> instances = new HashSet<>();
        try {
            // 톰캣의 webapps 폴더 내 WEB-INF/classes 경로 가져오기
            String classPath = servletContext.getRealPath("/WEB-INF/classes/");

            // C:\Program Files\Apache Software Foundation\Tomcat 11.0\webapps\ROOT\WEB-INF\classes\
            File slashDir = new File(classPath);
            File dotToSlashDir = new File(slashDir, pkg.replace(".", File.separator));

            for (File file : dotToSlashDir.listFiles()) {
                // System.out.println(file.getName());

                String className = pkg + "." + file.getName().replace(".class", "");
                // System.out.println(className);

                try {
                    Class cls = Class.forName(className);
                    if (cls.isAnnotationPresent(Controller.class)) {
                        // System.out.println("Controller 어노테이션");
                        Object instance = cls.getDeclaredConstructor().newInstance();
                        instances.add(instance);
                    }
                } catch (Exception e) {
                    throw new RuntimeException(e);
                }
            }

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

어노테이션 코드

package org.example.demo10.core;

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.TYPE)
public @interface Controller {
}

package org.example.demo10.core;

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.METHOD)
public @interface RequestMapping {
    String value();
}

UserController, BoardController 코드

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 "login";
    }
}

package org.example.demo10.controller;

import org.example.demo10.core.Controller;

@Controller
public class BoardController {
}

jsp파일

join

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

login

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