Spring Security 入门（四）：自定义-Filter

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

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/[email protected]
SECURITYCONTEXTFILTER	SecurityContextPersistenceFilter	http
CONCURRENTSESSIONFILTER	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
PREAUTHFILTER	AbstractPreAuthenticatedProcessingFilter( Subclasses)	N/A
CAS_FILTER	CasAuthenticationFilter	N/A
FORMLOGINFILTER	UsernamePasswordAuthenticationFilter	http/form-login
BASICAUTHFILTER	BasicAuthenticationFilter	http/http-basic
SERVLETAPISUPPORT_FILTER	SecurityContextHolderAwareRequestFilter	http/@servlet-api-provision
JAASAPISUPPORT_FILTER	JaasApiIntegrationFilter	http/@jaas-api-provision
REMEMBERMEFILTER	RememberMeAuthenticationFilter	http/remember-me
ANONYMOUS_FILTER	AnonymousAuthenticationFilter	http/anonymous
SESSIONMANAGEMENTFILTER	SessionManagementFilter	session-management
EXCEPTIONTRANSLATIONFILTER	ExceptionTranslationFilter	http
FILTERSECURITYINTERCEPTOR	FilterSecurityInterceptor	http
SWITCHUSERFILTER	SwitchUserFilter	N/A

过滤器顺序从上到下

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 beforeFilter) 在 beforeFilter 之前添加 filter
addFilterAfter(Filter filter, Class afterFilter) 在 afterFilter 之后添加 filter
addFilterAt(Filter filter, Class 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。