Spring Security In Action Second Edition Fixed < DELUXE - 2026 >

public class JwtAuthenticationFilter extends OncePerRequestFilter @Override protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain chain) throws IOException, ServletException !header.startsWith("Bearer ")) chain.doFilter(request, response); return; String token = header.substring(7); String username = jwtService.extractUsername(token); if (username != null && SecurityContextHolder.getContext().getAuthentication() == null) UserDetails user = userDetailsService.loadUserByUsername(username); UsernamePasswordAuthenticationToken auth = new UsernamePasswordAuthenticationToken(user, null, user.getAuthorities()); // Critical: Set the context for this single request SecurityContextHolder.getContext().setAuthentication(auth); chain.doFilter(request, response); // No cleanup needed because STATELESS means the context dies with the request

"The best session is no session at all." — A mantra for modern Spring Security developers. spring security in action second edition

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: FilterChain chain) throws IOException