spring 跨域CORS Filter

方案一
spring中可以采用的跨域配置方式如下：

RequestMapping
在一般性的配置中，在controller前添加@CrossOrigin即可使用spring的默认配置，允许跨域
该注解也可以配置一些设定，适合针对个别的controller

@CrossOrigin

方案二
webconfig的方式配置全局跨域

@Configuration
public class JxWebMvcConfiguration extends WebMvcConfigurerAdapter {

  /**
  * Cross Origin Resource Support(CORS) for the Spring MVC.
  * automatically.
  * https://my.oschina.net/wangnian/blog/689020
  * http://spring.io/guides/gs/rest-service-cors/
  */
  /* @Override
  public void addCorsMappings(CorsRegistry registry) {
  registry.addMapping("*")
  .allowedOrigins("*").exposedHeaders("x-total-count","x-auth-token")
  .allowedMethods("GET", "HEAD", "POST", "PUT", "PATCH", "DELETE", "OPTIONS", "TRACE");
  }*/
}

这种方式的缺陷是，filter的顺序是固定的，在引入第三方组件的时候可能会因为filter滞后，导致出错
方案三
定制Filter

@Bean
public FilterRegistrationBean corsFilter() {
  UrlBasedCorsConfigurationSource source = new UrlBasedCorsConfigurationSource();
  CorsConfiguration config = new CorsConfiguration();
  config.setAllowCredentials(true);
  config.addAllowedOrigin("*");
  config.addAllowedHeader("*");
  config.addAllowedMethod("*");
  source.registerCorsConfiguration("/**", config);
  FilterRegistrationBean bean = new FilterRegistrationBean(new CorsFilter(source));
  bean.setOrder(0);
  return bean;
}

方案3缺陷
在3中，使用zuul的时候，的确解决了跨域问题，但是spring security的filter还是在其前边，引起登录的时候不能正常捕获401错误

@Bean
    public Filter corsFilter() {
        UrlBasedCorsConfigurationSource source = new UrlBasedCorsConfigurationSource();
        CorsConfiguration config = new CorsConfiguration();
        config.setAllowCredentials(true);
        config.addAllowedOrigin("*");
        config.addAllowedHeader("*");
        config.addAllowedMethod("*");
        config.addExposedHeader("x-auth-token");
        config.addExposedHeader("x-total-count");
        source.registerCorsConfiguration("/**", config);
        return new CorsFilter(source);
    }

    @Override
    protected void configure(HttpSecurity httpSecurity) throws Exception {       
        httpSecurity.addFilterBefore(corsFilter(), ChannelProcessingFilter.class);
      }

spring security 标准Filter及其在filter chain的顺序

Alias	Filter Class	Namespace Element or Attribute
CHANNEL_FILTER	ChannelProcessingFilter	http/intercept-url@requires-channel
SECURITY_CONTEXT_FILTER	SecurityContextPersistenceFilter	http
CONCURRENT_SESSION_FILTER	ConcurrentSessionFilter	session-management/concurrency-control
HEADERS_FILTER	HeaderWriterFilter	http/headers
CSRF_FILTER	CsrfFilter	http/csrf
LOGOUT_FILTER	LogoutFilter	http/logout
X509_FILTER	X509AuthenticationFilter	http/x509
PRE_AUTH_FILTER	AstractPreAuthenticatedProcessingFilter  Subclasses	N/A
CAS_FILTER	CasAuthenticationFilter	N/A
FORM_LOGIN_FILTER	UsernamePasswordAuthenticationFilter	http/form-login
BASIC_AUTH_FILTER	BasicAuthenticationFilter	http/http-basic
SERVLET_API_SUPPORT_FILTER	SecurityContextHolderAwareRequestFilter	http/@servlet-api-provision
JAAS_API_SUPPORT_FILTER	JaasApiIntegrationFilter	http/@jaas-api-provision
REMEMBER_ME_FILTER	RememberMeAuthenticationFilter	http/remember-me
ANONYMOUS_FILTER	AnonymousAuthenticationFilter	http/anonymous
SESSION_MANAGEMENT_FILTER	SessionManagementFilter	session-management
EXCEPTION_TRANSLATION_FILTER	ExceptionTranslationFilter	http
FILTER_SECURITY_INTERCEPTOR	FilterSecurityInterceptor	http
SWITCH_USER_FILTER	SwitchUserFilter	N/A

参考（4.3.6）

http://docs.spring.io/spring-security/site/docs/3.2.8.RELEASE/reference/htmlsingle/#ns-web-advanced