JWT 인증 구현

// JwtTokenProvider.java
@Component
public class JwtTokenProvider {
    @Value("${jwt.secret}")
    private String secretKey;
    private final long ACCESS_TTL = 1000L * 60 * 30;   // 30분
    private final long REFRESH_TTL = 1000L * 60 * 60 * 24 * 7; // 7일

    private Key getKey() {
        return Keys.hmacShaKeyFor(secretKey.getBytes());
    }

    public String createAccessToken(Long userId, String role) {
        return Jwts.builder()
            .setSubject(String.valueOf(userId))
            .claim("role", role)
            .setIssuedAt(new Date())
            .setExpiration(new Date(System.currentTimeMillis() + ACCESS_TTL))
            .signWith(getKey(), SignatureAlgorithm.HS256)
            .compact();
    }

    public Claims getClaims(String token) {
        return Jwts.parserBuilder()
            .setSigningKey(getKey()).build()
            .parseClaimsJws(token).getBody();
    }

    public boolean isValid(String token) {
        try { getClaims(token); return true; }
        catch (JwtException e) { return false; }
    }
}

# application.properties
jwt.secret=your-256-bit-secret-key-here-must-be-long-enough