In the first edition of Spring Security in Action , many readers fell in love with the classic "formLogin" flow. But in the second edition, Laurentiu Spilca makes one thing crystal clear: In a modern cloud-native world, servers must forget.
The most critical piece from the second edition is the custom filter. It intercepts every request, grabs the Authorization: Bearer header, and populates the SecurityContextHolder for that request only (because there is no session to carry it forward).
"The best session is no session at all." — A mantra for modern Spring Security developers.
To go stateless, we need to disable session creation entirely:
@Configuration @EnableWebSecurity public class StatelessSecurityConfig @Bean public SecurityFilterChain filterChain(HttpSecurity http) throws Exception http .sessionManagement(session -> session .sessionCreationPolicy(SessionCreationPolicy.STATELESS) ) .authorizeHttpRequests(auth -> auth .requestMatchers("/login", "/refresh").permitAll() .anyRequest().authenticated() ); // No formLogin() - we use a custom filter return http.build();
With sessions disabled, every request must carry its own proof of identity. Here is a simplified implementation of a JWT service as described in the book:
@Component public class JwtService private final SecretKey key = Keys.secretKeyFor(SignatureAlgorithm.HS256); private final long EXPIRATION = 86400000; // 24 hours public String generateToken(String username) return Jwts.builder() .setSubject(username) .setIssuedAt(new Date()) .setExpiration(new Date(System.currentTimeMillis() + EXPIRATION)) .signWith(key) .compact();
public String extractUsername(String token) return Jwts.parserBuilder() .setSigningKey(key) .build() .parseClaimsJws(token) .getBody() .getSubject();