java如何将if语句逻辑重写为web安全过滤器中的反应式方法？

Question

我对ProjectReactor和WebFlux很熟悉，我想将我目前的传统、阻塞式安全过滤器改写为反应式安全过滤器，即：

当前筛选器如下所示：

@Component
@Slf4j
public class WhitelistingFilter extends OncePerRequestFilter {

  private static final String SECURITY_PROPERTIES = "security.properties";
  private final Properties securityProperties = readConfigurationFile(SECURITY_PROPERTIES);
  private final String whitelistingEnabled = securityProperties.getProperty("whitelisting.enabled", FALSE.toString());

  private final RedisTemplate<String, Object> whitelistingRedisTemplate;
  private final AwsCognitoIdTokenProcessor awsCognitoIdTokenProcessor;

  public WhitelistingFilter(
      @Qualifier("whitelistingRedisTemplate")
          RedisTemplate<String, Object> whitelistingRedisTemplate,
      AwsCognitoIdTokenProcessor awsCognitoIdTokenProcessor) {
    this.whitelistingRedisTemplate = whitelistingRedisTemplate;
    this.awsCognitoIdTokenProcessor = awsCognitoIdTokenProcessor;
  }

  @Override
  protected boolean shouldNotFilter(@NonNull HttpServletRequest request) {
    AntPathMatcher pathMatcher = new AntPathMatcher();
    return Stream.of(USER_LOGIN_URL, ADMIN_LOGIN_URL, SIGNUP_BY_ADMIN_URL, SIGNUP_URL, LOGOUT_URL)
            .anyMatch(p -> pathMatcher.match(p, request.getServletPath())) || whitelistingDisabled();
  }

  private boolean whitelistingDisabled() {
    return FALSE.toString().equalsIgnoreCase(whitelistingEnabled);
  }

  @Override
  protected void doFilterInternal(@NonNull HttpServletRequest httpServletRequest, @NonNull HttpServletResponse httpServletResponse, @NonNull FilterChain filterChain) {
    try {
      Authentication authentication = awsCognitoIdTokenProcessor.getAuthentication(httpServletRequest);
      Optional<String> username = Optional.ofNullable(authentication.getName());
      if (username.isPresent() && usernameWhitelisted(username.get())) {
        log.info("User with username: {} is present in whitelisting", username.get());
        filterChain.doFilter(httpServletRequest, httpServletResponse);
      } else {
        httpServletResponse.setStatus(HttpServletResponse.SC_UNAUTHORIZED);
        log.error("Username: {} not whitelisted or empty", username.orElse(""));
      }

    } catch (Exception e) {
      logger.error("Error occurred while checking user in redis whitelisting", e);
      SecurityContextHolder.clearContext();
    }
  }

  private boolean usernameWhitelisted(String username) {
    return Boolean.TRUE.equals(whitelistingRedisTemplate.hasKey(WHITELISTING_PREFIX + username));
  }
}

新的、不完整的、被动的方法类如下所示：

@Component
@Slf4j
public class WhitelistingFilter implements WebFilter {

  private static final String SECURITY_PROPERTIES = "security.properties";
  public final List<String> whitelistedUrls =
      List.of(USER_LOGIN_URL, ADMIN_LOGIN_URL, SIGNUP_BY_ADMIN_URL, SIGNUP_URL, LOGOUT_URL);

  private final Properties securityProperties = readConfigurationFile(SECURITY_PROPERTIES);
  private final String whitelistingEnabled = securityProperties.getProperty("whitelisting.enabled", FALSE.toString());
  private final ReactiveRedisOperations<String, Object> whitelistingRedisTemplate;
  private final AuthenticationManager authenticationManager;

  public WhitelistingFilter(
      @Qualifier("reactiveWhitelistingRedisTemplate")
          ReactiveRedisOperations<String, Object> whitelistingRedisTemplate,
      AuthenticationManager authenticationManager) {
    this.whitelistingRedisTemplate = whitelistingRedisTemplate;
    this.authenticationManager = authenticationManager;
  }

  @Override
  public Mono<Void> filter(ServerWebExchange exchange, WebFilterChain chain) {

    Mono<String> username =
        ReactiveSecurityContextHolder.getContext()
            .map(SecurityContext::getAuthentication)
            .map(Authentication::getName);
    //logic here
    
  }

  private Mono<Boolean> whitelistingDisabled() {
    return Mono.just(FALSE.toString().equalsIgnoreCase(whitelistingEnabled));
  }

  private Mono<Boolean> usernameWhitelisted(Mono<String> username) {
    return whitelistingRedisTemplate.hasKey(WHITELISTING_PREFIX + username);
  }
}

我更改了usernameWhitelisted()和whitelistingDisabled()方法，以返回Mono的，但我不知道如何验证用户名是否是白名单，以及在被动方法中是否启用了白名单。我试图做某事

username.flatMap(u -> {
  if(two conditions here) 
})

但通过这种方法，我为if语句提供了Mono，这与Java语义相矛盾。对于如何重写代码并使其以被动方式工作的建议，我将不胜感激