Spring Security 入门：自定义 Filter

本文解决问题

将自定义的 Filter 加入到 Spring Security 中的 Filter 链中的指定位置。

Spring Security 默认的过滤器链

官网位置：http://docs.spring.io/spring-security/site/docs/5.0.0.M1/reference/htmlsingle/#ns-custom-filters

别名	类名称	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	AbstractPreAuthenticatedProcessingFilter( 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

过滤器顺序从上到下

自定义 Filter

自定义的 Filter 建议继承 GenericFilterBean，本文示例：

public class BeforeLoginFilter extends GenericFilterBean {

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        System.out.println("This is a filter before UsernamePasswordAuthenticationFilter.");
        // 继续调用 Filter 链
        filterChain.doFilter(servletRequest, servletResponse);
    }
}

配置自定义 Filter 在 Spring Security 过滤器链中的位置

配置很简单，本文示例：

protected void configure(HttpSecurity http) throws Exception {
        http
                .authorizeRequests()
                .antMatchers("/").permitAll()
                .antMatchers("/user/**").hasRole("USER")
                .and()
                .formLogin().loginPage("/login").defaultSuccessUrl("/user")
                .and()
                .logout().logoutUrl("/logout").logoutSuccessUrl("/login");

        // 在 UsernamePasswordAuthenticationFilter 前添加 BeforeLoginFilter
        http.addFilterBefore(new BeforeLoginFilter(), UsernamePasswordAuthenticationFilter.class);

        // 在 CsrfFilter 后添加 AfterCsrfFilter
        http.addFilterAfter(new AfterCsrfFilter(), CsrfFilter.class);
    }

说明：
HttpSecurity 有三个常用方法来配置：

• addFilterBefore(Filter filter, Class<? extends Filter> beforeFilter)
  在 beforeFilter 之前添加 filter
• addFilterAfter(Filter filter, Class<? extends Filter> afterFilter)
  在 afterFilter 之后添加 filter
• addFilterAt(Filter filter, Class<? extends Filter> atFilter)
  在 atFilter 相同位置添加 filter， 此 filter 不覆盖 filter

通过在不同 Filter 的 doFilter() 方法中加断点调试，可以判断哪个 filter 先执行，从而判断 filter 的执行顺序 。

作者：Anoyi
链接：https://www.jianshu.com/p/deb512b41f99
來源：简书
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