Feat: JWT 인증/인가 인프라 초기 세팅 (#32)

.env.default

@@ -0,0 +1 @@
+JWT_SECRET=your-secret-key

build.gradle.kts

@@ -39,6 +39,11 @@ dependencies {
     testRuntimeOnly("org.junit.platform:junit-platform-launcher")
     implementation("org.springdoc:springdoc-openapi-starter-webmvc-ui:2.8.13")
     implementation ("io.github.cdimascio:dotenv-java:3.0.0")
+
+    // JWT
+    implementation("io.jsonwebtoken:jjwt-api:0.12.6")
+    runtimeOnly("io.jsonwebtoken:jjwt-impl:0.12.6")
+    runtimeOnly("io.jsonwebtoken:jjwt-jackson:0.12.6")
 }
 
 tasks.withType<Test> {

src/main/java/com/back/global/exception/ErrorCode.java

@@ -10,7 +10,16 @@ public enum ErrorCode {
     // ======================== 공통 에러 ========================
     BAD_REQUEST(HttpStatus.BAD_REQUEST, "COMMON_400", "잘못된 요청입니다."),
     FORBIDDEN(HttpStatus.FORBIDDEN, "COMMON_403", "접근 권한이 없습니다."),
-    NOT_FOUND(HttpStatus.NOT_FOUND, "COMMON_404", "요청하신 리소스를 찾을 수 없습니다.");
+    NOT_FOUND(HttpStatus.NOT_FOUND, "COMMON_404", "요청하신 리소스를 찾을 수 없습니다."),
+
+    // ======================== 인증/인가 에러 ========================
+    UNAUTHORIZED(HttpStatus.UNAUTHORIZED, "AUTH_401", "인증이 필요합니다."),
+    INVALID_TOKEN(HttpStatus.UNAUTHORIZED, "AUTH_401", "유효하지 않은 토큰입니다."),
+    EXPIRED_ACCESS_TOKEN(HttpStatus.UNAUTHORIZED, "AUTH_401", "만료된 액세스 토큰입니다."),
+    EXPIRED_REFRESH_TOKEN(HttpStatus.UNAUTHORIZED, "AUTH_401", "만료된 리프레시 토큰입니다."),
+    REFRESH_TOKEN_REUSE(HttpStatus.FORBIDDEN, "AUTH_403", "재사용된 리프레시 토큰입니다."),
+    ACCESS_DENIED(HttpStatus.FORBIDDEN, "AUTH_403", "권한이 없습니다.");
+
 
     private final HttpStatus status;
     private final String code;

src/main/java/com/back/global/security/CustomUserDetails.java

@@ -0,0 +1,58 @@
+package com.back.global.security;
+
+import lombok.AllArgsConstructor;
+import lombok.Getter;
+import org.springframework.security.core.authority.SimpleGrantedAuthority;
+import org.springframework.security.core.userdetails.UserDetails;
+
+import java.util.Collection;
+import java.util.List;
+
+/**
+ * Spring Security에서 사용하는 사용자 인증 정보 클래스
+ * - JWT에서 파싱한 사용자 정보를 담고 있음
+ */
+@Getter
+@AllArgsConstructor
+public class CustomUserDetails implements UserDetails {
+    private Long userId;
+    private String username;
+    private String role;
+
+    @Override
+    public Collection<SimpleGrantedAuthority> getAuthorities() {
+        // Spring Security 권한 체크는 "ROLE_" prefix 필요
+        return List.of(new SimpleGrantedAuthority("ROLE_" + role));
+    }
+
+    @Override
+    public String getPassword() {
+        // JWT 인증에서는 비밀번호를 사용하지 않음
+        return null;
+    }
+
+    @Override
+    public String getUsername() {
+        return username;
+    }
+
+    @Override
+    public boolean isAccountNonExpired() {
+        return true;
+    }
+
+    @Override
+    public boolean isAccountNonLocked() {
+        return true;
+    }
+
+    @Override
+    public boolean isCredentialsNonExpired() {
+        return true;
+    }
+
+    @Override
+    public boolean isEnabled() {
+        return true;
+    }
+}

src/main/java/com/back/global/security/JwtAccessDeniedHandler.java

@@ -0,0 +1,37 @@
+package com.back.global.security;
+
+import com.back.global.common.dto.RsData;
+import com.back.global.exception.ErrorCode;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import jakarta.servlet.http.HttpServletRequest;
+import jakarta.servlet.http.HttpServletResponse;
+import org.springframework.security.access.AccessDeniedException;
+import org.springframework.security.web.access.AccessDeniedHandler;
+import org.springframework.stereotype.Component;
+
+import java.io.IOException;
+
+/**
+ * 인가 실패(403 Forbidden) 처리 클래스
+ * - 인증은 되었으나, 권한(Role)이 부족한 경우
+ * - Json 형태로 에러 응답을 반환
+ */
+@Component
+public class JwtAccessDeniedHandler implements AccessDeniedHandler {
+    private final ObjectMapper objectMapper = new ObjectMapper();
+
+    @Override
+    public void handle(
+            HttpServletRequest request,
+            HttpServletResponse response,
+            AccessDeniedException accessDeniedException
+    ) throws IOException {
+
+        response.setContentType("application/json;charset=UTF-8");
+        response.setStatus(HttpServletResponse.SC_FORBIDDEN);
+
+        RsData<Void> body = RsData.fail(ErrorCode.ACCESS_DENIED);
+
+        response.getWriter().write(objectMapper.writeValueAsString(body));
+    }
+}

src/main/java/com/back/global/security/JwtAuthenticationEntryPoint.java

@@ -0,0 +1,38 @@
+package com.back.global.security;
+
+import com.back.global.common.dto.RsData;
+import com.back.global.exception.ErrorCode;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import jakarta.servlet.http.HttpServletRequest;
+import jakarta.servlet.http.HttpServletResponse;
+import org.springframework.security.core.AuthenticationException;
+import org.springframework.security.web.AuthenticationEntryPoint;
+import org.springframework.stereotype.Component;
+
+import java.io.IOException;
+
+/**
+ * 인증 실패(401 Unauthorized) 처리 클래스
+ * - JwtAuthenticationFilter에서 토큰이 없거나 잘못된 경우
+ * - 인증되지 않은 사용자가 보호된 API에 접근하려는 경우
+ * - Json 형태로 에러 응답을 반환
+ */
+@Component
+public class JwtAuthenticationEntryPoint implements AuthenticationEntryPoint {
+    private final ObjectMapper objectMapper = new ObjectMapper();
+
+    @Override
+    public void commence(
+            HttpServletRequest request,
+            HttpServletResponse response,
+            AuthenticationException authException
+    ) throws IOException {
+
+        response.setContentType("application/json;charset=UTF-8");
+        response.setStatus(HttpServletResponse.SC_UNAUTHORIZED);
+
+        RsData<Void> body = RsData.fail(ErrorCode.UNAUTHORIZED);
+
+        response.getWriter().write(objectMapper.writeValueAsString(body));
+    }
+}

src/main/java/com/back/global/security/JwtAuthenticationFilter.java

@@ -0,0 +1,56 @@
+package com.back.global.security;
+
+import jakarta.servlet.FilterChain;
+import jakarta.servlet.ServletException;
+import jakarta.servlet.http.HttpServletRequest;
+import jakarta.servlet.http.HttpServletResponse;
+import lombok.RequiredArgsConstructor;
+import org.springframework.security.core.Authentication;
+import org.springframework.security.core.context.SecurityContextHolder;
+import org.springframework.stereotype.Component;
+import org.springframework.web.filter.OncePerRequestFilter;
+
+import java.io.IOException;
+
+/**
+ * JWT 인증을 처리하는 필터
+ * - 모든 요청에 대해 JWT 토큰을 검사
+ * - 토큰이 유효하면 Authentication 객체를 생성하여 SecurityContext에 저장
+ */
+@Component
+@RequiredArgsConstructor
+public class JwtAuthenticationFilter extends OncePerRequestFilter {
+    private final JwtTokenProvider jwtTokenProvider;
+
+    @Override
+    protected void doFilterInternal(
+            HttpServletRequest request, HttpServletResponse response, FilterChain filterChain
+    ) throws ServletException, IOException {
+
+        // Request Header에서 토큰 추출
+        String token = resolveToken(request);
+
+        // 토큰이 유효한 경우에만 Authentication 객체 생성 및 SecurityContext에 저장
+        if (token != null && jwtTokenProvider.validateToken(token)) {
+            Authentication authentication = jwtTokenProvider.getAuthentication(token);
+            SecurityContextHolder.getContext().setAuthentication(authentication);
+        }
+
+        // 다음 필터로 요청 전달
+        filterChain.doFilter(request, response);
+    }
+
+    /**
+     * Request의 Authorization 헤더에서 JWT 토큰을 추출
+     *
+     * @param request HTTP 요청 객체
+     * @return JWT 토큰 문자열 또는 null
+     */
+    private String resolveToken(HttpServletRequest request) {
+        String bearerToken = request.getHeader("Authorization");
+        if (bearerToken != null && bearerToken.startsWith("Bearer ")) {
+            return bearerToken.substring(7);
+        }
+        return null;
+    }
+}

src/main/java/com/back/global/security/JwtTokenProvider.java

@@ -0,0 +1,142 @@
+package com.back.global.security;
+
+import com.back.global.exception.CustomException;
+import com.back.global.exception.ErrorCode;
+import io.jsonwebtoken.Claims;
+import io.jsonwebtoken.ExpiredJwtException;
+import io.jsonwebtoken.JwtException;
+import io.jsonwebtoken.Jwts;
+import io.jsonwebtoken.security.Keys;
+import jakarta.annotation.PostConstruct;
+import org.springframework.beans.factory.annotation.Value;
+import org.springframework.security.authentication.UsernamePasswordAuthenticationToken;
+import org.springframework.security.core.Authentication;
+import org.springframework.security.core.authority.SimpleGrantedAuthority;
+import org.springframework.stereotype.Component;
+
+import javax.crypto.SecretKey;
+import java.util.Date;
+import java.util.List;
+
+/**
+ * JWT 생성 및 검증을 담당하는 Provider 클래스
+ * - Access Token, Refresh Token 생성
+ * - 토큰 검증 및 파싱
+ * - Authentication 객체 생성 (Spring Security 연동)
+ */
+@Component
+public class JwtTokenProvider {
+
+    @Value("${jwt.secret}")
+    private String secretKey;
+
+    @Value("${jwt.access-token-expiration}")
+    private long accessTokenExpirationInSeconds;
+
+    @Value("${jwt.refresh-token-expiration}")
+    private long refreshTokenExpirationInSeconds;
+
+    private SecretKey key;
+
+    @PostConstruct
+    public void init() {
+        this.key = Keys.hmacShaKeyFor(secretKey.getBytes());
+    }
+
+    /**
+     * Access Token 생성
+     *
+     * @param userId   사용자 PK
+     * @param username 로그인 ID
+     * @param role     권한
+     * @return JWT Access Token 문자열
+     */
+    public String createAccessToken(Long userId, String username, String role) {
+        Date now = new Date();
+        Date expiryDate = new Date(now.getTime() + accessTokenExpirationInSeconds * 1000);
+
+        return Jwts.builder()
+                .subject(username)
+                .claim("userId", userId)
+                .claim("role", role)
+                .issuedAt(now)
+                .expiration(expiryDate)
+                .signWith(key)
+                .compact();
+    }
+
+    /**
+     * Refresh Token 생성
+     *
+     * @param userId 사용자 PK
+     * @return JWT Refresh Token 문자열
+     */
+    public String createRefreshToken(Long userId) {
+        Date now = new Date();
+        Date expiryDate = new Date(now.getTime() + refreshTokenExpirationInSeconds * 1000);
+
+        return Jwts.builder()
+                .subject(String.valueOf(userId))
+                .issuedAt(now)
+                .expiration(expiryDate)
+                .signWith(key)
+                .compact();
+    }
+
+    /**
+     * JWT 토큰에서 인증 정보 추출
+     *
+     * @param token JWT Access Token
+     * @return 인증 정보가 담긴 Authentication 객체
+     */
+    public Authentication getAuthentication(String token) {
+        Claims claims = parseClaims(token);
+        Long userId = claims.get("userId", Long.class);
+        String username = claims.getSubject();
+        String role = claims.get("role", String.class);
+
+        SimpleGrantedAuthority authority = new SimpleGrantedAuthority("ROLE_" + role);
+        CustomUserDetails principal = new CustomUserDetails(userId, username, role);
+
+        return new UsernamePasswordAuthenticationToken(principal, token, List.of(authority));
+    }
+
+    /**
+     * JWT 토큰 검증
+     *
+     * @param token JWT Access Token
+     * @return 유효한 토큰이면 true, 그렇지 않으면 false
+     */
+    public boolean validateToken(String token) {
+        try {
+            Jwts.parser()
+                    .verifyWith(key)
+                    .build()
+                    .parseSignedClaims(token);
+            return true;
+        } catch (JwtException e) {
+            return false;
+        }
+    }
+
+    /**
+     * JWT 파싱
+     *
+     * @param token JWT 토큰
+     * @return 토큰의 Claims
+     * @throws CustomException 토큰이 유효하지 않은 경우
+     */
+    private Claims parseClaims(String token) {
+        try {
+            return Jwts.parser()
+                    .verifyWith(key)
+                    .build()
+                    .parseSignedClaims(token)
+                    .getPayload();
+        } catch (ExpiredJwtException e) {
+            return e.getClaims();
+        } catch (JwtException e) {
+            throw new CustomException(ErrorCode.INVALID_TOKEN);
+        }
+    }
+}