需求：前端VUE项目需要在HTTP header添加JWT token发送到Spring后端认证。

尝试：使用Spring官方的配置

@Configuration
@EnableWebFlux
public class WebConfig implements WebFluxConfigurer {

    @Override
    public void addCorsMappings(CorsRegistry registry) {

        registry.addMapping("/api/**")
            .allowedOrigins("http://domain2.com")
            .allowedMethods("PUT", "DELETE")
            .allowedHeaders("header1", "header2", "header3")
            .exposedHeaders("header1", "header2")
            .allowCredentials(true).maxAge(3600);

        // Add more mappings...
    }
}

@Bean
CorsWebFilter corsFilter() {

    CorsConfiguration config = new CorsConfiguration();

    // Possibly...
    // config.applyPermitDefaultValues()

    config.setAllowCredentials(true);
    config.addAllowedOrigin("http://domain1.com");
    config.addAllowedHeader("");
    config.addAllowedMethod("");

    UrlBasedCorsConfigurationSource source = new UrlBasedCorsConfigurationSource();
    source.registerCorsConfiguration("/**", config);

    return new CorsWebFilter(source);
}

结果都是报错：

Failed to load http://127.0.0.1:8080/api/company/statistics: 
Response to preflight request doesn't pass access control check: 
No 'Access-Control-Allow-Origin' header is present on the requested resource. 
Origin 'http://localhost:8081' is therefore not allowed access. The response had HTTP status code 401.

最后解决方案：

@Component
@Order(Ordered.HIGHEST_PRECEDENCE)
public class CORSFilter implements WebFilter {

    @Override
    public Mono<Void> filter(ServerWebExchange swe, WebFilterChain wfc) {
        ServerHttpRequest request = swe.getRequest();
        if (CorsUtils.isCorsRequest(request)) {
            ServerHttpResponse response = swe.getResponse();
            HttpHeaders headers = response.getHeaders();
            headers.add("Access-Control-Allow-Origin", "*");
            headers.add("Access-Control-Allow-Methods", "*");
            headers.add("Access-Control-Max-Age", "3600");
            headers.add("Access-Control-Allow-Headers", "my-token");
            headers.add("Access-Control-Allow-Headers", "Content-Type");
            if (request.getMethod() == HttpMethod.OPTIONS) {
                response.setStatusCode(HttpStatus.OK);
                return Mono.empty();
            }
        }
        return wfc.filter(swe);
    }
}

@EnableWebFluxSecurity
@EnableReactiveMethodSecurity
public class SecurityConfig {

    @Autowired
    private AuthenticationManager authenticationManager;

    @Autowired
    private CustomSecurityContextRepository securityContextRepository;

    @Bean
    public SecurityWebFilterChain springSecurityFilterChain(ServerHttpSecurity http) throws Exception {
        return http.csrf().disable()
                .formLogin().disable()
                .httpBasic().disable()
                .authenticationManager(authenticationManager)
                .securityContextRepository(securityContextRepository)
                .authorizeExchange()
                .pathMatchers("/api/auth").permitAll()
                .pathMatchers("/api/public").permitAll()
                .anyExchange().authenticated()
                .and().build();
    }
}

重要地方：@Order(Ordered.HIGHEST_PRECEDENCE)