JWTUtil

package com.sample.oauthjwt.jwt;

import io.jsonwebtoken.Jwts;
import java.nio.charset.StandardCharsets;
import java.util.Date;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;

@Component
public class JWTUtil {

    private SecretKey secretKey;

    public JWTUtil(@Value("${spring.jwt.secret}")String secret){
        this.secretKey = new SecretKeySpec(secret.getBytes(StandardCharsets.UTF_8), Jwts.SIG.HS256.key().build().getAlgorithm());
    }

    public String getUsername(String token) {

        return Jwts.parser().verifyWith(secretKey).build().parseSignedClaims(token).getPayload().get("username", String.class);
    }

    public String getRole(String token) {

        return Jwts.parser().verifyWith(secretKey).build().parseSignedClaims(token).getPayload().get("role", String.class);
    }

    public Boolean isExpired(String token) {

        return Jwts.parser().verifyWith(secretKey).build().parseSignedClaims(token).getPayload().getExpiration().before(new Date());
    }

    public String createJwt(String username, String role, Long expiredMs) {

        return Jwts.builder()
                   .claim("username", username)
                   .claim("role", role)
                   .issuedAt(new Date(System.currentTimeMillis()))
                   .expiration(new Date(System.currentTimeMillis() + expiredMs))
                   .signWith(secretKey)
                   .compact();
    }

}

로그인 성공 JWT 발급

OAuth2 로그인이 성공하면 실행될 성공 핸들러를 커스텀해서 내부에 JWT 발급 구현을 진행

CustomSuccessHandler

SimpleUrlAuthenticationSuccessHandler 상속 받아서 작성

쿠키를 생성해서 클라이언트에 전달

package com.sample.oauthjwt.oauth2;

import com.sample.oauthjwt.dto.CustomOAuth2User;
import com.sample.oauthjwt.jwt.JWTUtil;
import jakarta.servlet.ServletException;
import jakarta.servlet.http.Cookie;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.Collection;
import java.util.Iterator;
import org.springframework.security.core.Authentication;
import org.springframework.security.core.GrantedAuthority;
import org.springframework.security.web.authentication.SimpleUrlAuthenticationSuccessHandler;
import org.springframework.stereotype.Component;

@Component
public class CustomSuccessHandler extends SimpleUrlAuthenticationSuccessHandler {

    private final JWTUtil jwtUtil;

    public CustomSuccessHandler(JWTUtil jwtUtil){
        this.jwtUtil = jwtUtil;
    }

    @Override
    public void onAuthenticationSuccess(HttpServletRequest request, HttpServletResponse response, Authentication authentication) throws IOException, ServletException {

        //OAuth2User
        CustomOAuth2User customUserDetails = (CustomOAuth2User) authentication.getPrincipal();

        String username = customUserDetails.getUsername();

        Collection<? extends GrantedAuthority> authorities = authentication.getAuthorities();
        Iterator<? extends GrantedAuthority> iterator = authorities.iterator();
        GrantedAuthority auth = iterator.next();
        String role = auth.getAuthority();

        String token = jwtUtil.createJwt(username, role, 60*60*60L);

        response.addCookie(createCookie("Authorization", token));
        response.sendRedirect("<http://localhost:3000/>");
    }

    private Cookie createCookie(String key, String value) {

        Cookie cookie = new Cookie(key, value);
        cookie.setMaxAge(60*60*60);
        //cookie.setSecure(true); // https일때
        cookie.setPath("/");
        cookie.setHttpOnly(true);

        return cookie;
    }

}

JWTFilter

package com.sample.oauthjwt.jwt;

import com.sample.oauthjwt.dto.CustomOAuth2User;
import com.sample.oauthjwt.dto.UserDTO;
import jakarta.servlet.FilterChain;
import jakarta.servlet.ServletException;
import jakarta.servlet.http.Cookie;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;
import java.io.IOException;
import org.springframework.security.authentication.UsernamePasswordAuthenticationToken;
import org.springframework.security.core.Authentication;
import org.springframework.security.core.context.SecurityContextHolder;
import org.springframework.web.filter.OncePerRequestFilter;

public class JWTFilter extends OncePerRequestFilter {

    private final JWTUtil jwtUtil;

    public JWTFilter(JWTUtil jwtUtil) {

        this.jwtUtil = jwtUtil;
    }

    @Override
    protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain)
        throws ServletException, IOException {

        //cookie들을 불러온 뒤 Authorization Key에 담긴 쿠키를 찾음
        String authorization = null;
        Cookie[] cookies = request.getCookies();
        for (Cookie cookie : cookies) {

            System.out.println(cookie.getName());
            if (cookie.getName().equals("Authorization")) {

                authorization = cookie.getValue();
            }
        }

        //Authorization 헤더 검증
        if (authorization == null) {

            System.out.println("token null");
            filterChain.doFilter(request, response);

            //조건이 해당되면 메소드 종료 (필수)
            return;
        }

        //토큰
        String token = authorization;

        //토큰 소멸 시간 검증
        if (jwtUtil.isExpired(token)) {

            System.out.println("token expired");
            filterChain.doFilter(request, response);

            //조건이 해당되면 메소드 종료 (필수)
            return;
        }

        //토큰에서 username과 role 획득
        String username = jwtUtil.getUsername(token);
        String role = jwtUtil.getRole(token);

        //userDTO를 생성하여 값 set
        UserDTO userDTO = new UserDTO();
        userDTO.setUsername(username);
        userDTO.setRole(role);

        //UserDetails에 회원 정보 객체 담기
        CustomOAuth2User customOAuth2User = new CustomOAuth2User(userDTO);

        //스프링 시큐리티 인증 토큰 생성
        Authentication authToken = new UsernamePasswordAuthenticationToken(customOAuth2User, null, customOAuth2User.getAuthorities());
        //세션에 사용자 등록
        SecurityContextHolder.getContext().setAuthentication(authToken);

        filterChain.doFilter(request, response);

    }
}

Security Config 수정

CustomSuccessHandler, JWTUtil 주입

    private final CustomOAuth2UserService customOAuth2UserService;
    private final CustomSuccessHandler customSuccessHandler;
    private final JWTUtil jwtUtil;

    public SecurityConfig(CustomOAuth2UserService customOAuth2UserService, CustomSuccessHandler customSuccessHandler, JWTUtil jwtUtil){
        this.customOAuth2UserService = customOAuth2UserService;
        this.customSuccessHandler = customSuccessHandler;
        this.jwtUtil = jwtUtil;
    }

CustomSuccessHandler(oauth2에), JWTFilter 추가

        //JWTFilter 추가
        http
            .addFilterBefore(new JWTFilter(jwtUtil), UsernamePasswordAuthenticationFilter.class);

        //oauth2
        http
            .oauth2Login((oauth2) -> oauth2
                .userInfoEndpoint((userInfoEndpointConfig) -> userInfoEndpointConfig
                    .userService(customOAuth2UserService))
                .successHandler(customSuccessHandler));