前言
本文是接上一章 Spring Security系列之认证过程(六) 进一步分析Spring Security用户名密码登录授权是如何实现得；
类图
调试过程
使用debug方式启动https://github.com/longfeizheng/logback该项目，浏览器输入http://localhost:8080/persons,用户名随意，密码123456即可；
源码分析如图所示，显示了登录认证过程中的 filters 相关的调用流程，将几个自认为重要的 filters 标注了出来，
从图中可以看出执行的顺序。来看看几个作者认为比较重要的 Filter 的处理逻辑， UsernamePasswordAuthenticationFilter ， AnonymousAuthenticationFilter ， ExceptionTranslationFilter ， FilterSecurityInterceptor
以及相关的处理流程如下所述；
UsernamePasswordAuthenticationFilter整个调用流程是，先调用其父类 AbstractAuthenticationProcessingFilter.doFilter() 方法，然后再执行 UsernamePasswordAuthenticationFilter.attemptAuthentication() 方法进行验证；
AbstractAuthenticationProcessingFilter public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) throws IOException, ServletException { HttpServletRequest request = (HttpServletRequest) req; HttpServletResponse response = (HttpServletResponse) res; #1.判断当前的filter是否可以处理当前请求，不可以的话则交给下一个filter处理 if (!requiresAuthentication(request, response)) { chain.doFilter(request, response); return; } if (logger.isDebugEnabled()) { logger.debug("Request is to process authentication"); } Authentication authResult; try { #2.抽象方法由子类UsernamePasswordAuthenticationFilter实现 authResult = attemptAuthentication(request, response); if (authResult == null) { // return immediately as subclass has indicated that it hasn't completed // authentication return; } #2.认证成功后，处理一些与session相关的方法 sessionStrategy.onAuthentication(authResult, request, response); } catch (InternalAuthenticationServiceException failed) { logger.error( "An internal error occurred while trying to authenticate the user.", failed); #3.认证失败后的的一些操作 unsuccessfulAuthentication(request, response, failed); return; } catch (AuthenticationException failed) { // Authentication failed unsuccessfulAuthentication(request, response, failed); return; } // Authentication success if (continueChainBeforeSuccessfulAuthentication) { chain.doFilter(request, response); } #3. 认证成功后的相关回调方法 主要将当前的认证放到SecurityContextHolder中 successfulAuthentication(request, response, chain, authResult); } 复制代码整个程序的执行流程如下:
判断filter是否可以处理当前的请求，如果不可以则放行交给下一个filter 调用抽象方法attemptAuthentication进行验证，该方法由子类UsernamePasswordAuthenticationFilter实现 认证成功以后，回调一些与 session 相关的方法； 认证成功以后，认证成功后的相关回调方法；认证成功以后，认证成功后的相关回调方法； protected void successfulAuthentication(HttpServletRequest request, HttpServletResponse response, FilterChain chain, Authentication authResult) throws IOException, ServletException { if (logger.isDebugEnabled()) { logger.debug("Authentication success. Updating SecurityContextHolder to contain: " + authResult); } SecurityContextHolder.getContext().setAuthentication(authResult); rememberMeServices.loginSuccess(request, response, authResult); // Fire event if (this.eventPublisher != null) { eventPublisher.publishEvent(new InteractiveAuthenticationSuccessEvent( authResult, this.getClass())); } successHandler.onAuthenticationSuccess(request, response, authResult); } 复制代码 将当前认证成功的 Authentication 放置到 SecurityContextHolder 中； 将当前认证成功的 Authentication 放置到 SecurityContextHolder 中； 调用其它可扩展的 handlers 继续处理该认证成功以后的回调事件；（实现AuthenticationSuccessHandler接口即可） UsernamePasswordAuthenticationFilter public Authentication attemptAuthentication(HttpServletRequest request, HttpServletResponse response) throws AuthenticationException { #1.判断请求的方法必须为POST请求 if (postOnly && !request.getMethod().equals("POST")) { throw new AuthenticationServiceException( "Authentication method not supported: " + request.getMethod()); } #2.从request中获取username和password String username = obtainUsername(request); String password = obtainPassword(request); if (username == null) { username = ""; } if (password == null) { password = ""; } username = username.trim(); #3.构建UsernamePasswordAuthenticationToken（两个参数的构造方法setAuthenticated(false)） UsernamePasswordAuthenticationToken authRequest = new UsernamePasswordAuthenticationToken( username, password); // Allow subclasses to set the "details" property setDetails(request, authRequest); #4. 调用 AuthenticationManager 进行验证（子类ProviderManager遍历所有的AuthenticationProvider认证） return this.getAuthenticationManager().authenticate(authRequest); } 复制代码 认证请求的方法必须为POST 从request中获取 username 和 password 封装Authenticaiton的实现类UsernamePasswordAuthenticationToken，（UsernamePasswordAuthenticationToken调用两个参数的构造方法setAuthenticated(false)） 调用 AuthenticationManager 的 authenticate 方法进行验证；可参考ProviderManager部分； AnonymousAuthenticationFilter从上图中过滤器的执行顺序图中可以看出 AnonymousAuthenticationFilter 过滤器是在 UsernamePasswordAuthenticationFilter 等过滤器之后，如果它前面的过滤器都没有认证成功，Spring Security则为当前的 SecurityContextHolder 中添加一个 Authenticaiton 的匿名实现类 AnonymousAuthenticationToken ;
public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) throws IOException, ServletException { #1.如果前面的过滤器都没认证通过，则SecurityContextHolder中Authentication为空 if (SecurityContextHolder.getContext().getAuthentication() == null) { #2.为当前的SecurityContextHolder中添加一个匿名的AnonymousAuthenticationToken SecurityContextHolder.getContext().setAuthentication( createAuthentication((HttpServletRequest) req)); if (logger.isDebugEnabled()) { logger.debug("Populated SecurityContextHolder with anonymous token: '" + SecurityContextHolder.getContext().getAuthentication() + "'"); } } else { if (logger.isDebugEnabled()) { logger.debug("SecurityContextHolder not populated with anonymous token, as it already contained: '" + SecurityContextHolder.getContext().getAuthentication() + "'"); } } chain.doFilter(req, res); } #3.创建匿名的AnonymousAuthenticationToken protected Authentication createAuthentication(HttpServletRequest request) { AnonymousAuthenticationToken auth = new AnonymousAuthenticationToken(key, principal, authorities); auth.setDetails(authenticationDetailsSource.buildDetails(request)); return auth; } /** * Creates a filter with a principal named "anonymousUser" and the single authority * "ROLE_ANONYMOUS". * * @param key the key to identify tokens created by this filter */ ##.创建一个用户名为anonymousUser 授权为ROLE_ANONYMOUS public AnonymousAuthenticationFilter(String key) { this(key, "anonymousUser", AuthorityUtils.createAuthorityList("ROLE_ANONYMOUS")); } 复制代码 判断 SecurityContextHolder 中 Authentication 为否为空； 如果空则为当前的 SecurityContextHolder 中添加一个匿名的 AnonymousAuthenticationToken （用户名为 anonymousUser 的AnonymousAuthenticationToken） ExceptionTranslationFilterExceptionTranslationFilter 异常处理过滤器,该过滤器用来处理在系统认证授权过程中抛出的异常（也就是下一个过滤器 FilterSecurityInterceptor ）,主要是处理 AuthenticationException 和 AccessDeniedException 。
public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) throws IOException, ServletException { HttpServletRequest request = (HttpServletRequest) req; HttpServletResponse response = (HttpServletResponse) res; try { chain.doFilter(request, response); logger.debug("Chain processed normally"); } catch (IOException ex) { throw ex; } catch (Exception ex) { // Try to extract a SpringSecurityException from the stacktrace #.判断是不是AuthenticationException Throwable[] causeChain = throwableAnalyzer.determineCauseChain(ex); RuntimeException ase = (AuthenticationException) throwableAnalyzer .getFirstThrowableOfType(AuthenticationException.class, causeChain); if (ase == null) { #. 判断是不是AccessDeniedException ase = (AccessDeniedException) throwableAnalyzer.getFirstThrowableOfType( AccessDeniedException.class, causeChain); } if (ase != null) { handleSpringSecurityException(request, response, chain, ase); } else { // Rethrow ServletExceptions and RuntimeExceptions as-is if (ex instanceof ServletException) { throw (ServletException) ex; } else if (ex instanceof RuntimeException) { throw (RuntimeException) ex; } // Wrap other Exceptions. This shouldn't actually happen // as we've already covered all the possibilities for doFilter throw new RuntimeException(ex); } } } 复制代码 FilterSecurityInterceptor此过滤器为认证授权过滤器链中最后一个过滤器，该过滤器之后就是请求真正的 /persons 服务
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException { FilterInvocation fi = new FilterInvocation(request, response, chain); invoke(fi); } public void invoke(FilterInvocation fi) throws IOException, ServletException { if ((fi.getRequest() != null) && (fi.getRequest().getAttribute(FILTER_APPLIED) != null) && observeOncePerRequest) { // filter already applied to this request and user wants us to observe // once-per-request handling, so don't re-do security checking fi.getChain().doFilter(fi.getRequest(), fi.getResponse()); } else { // first time this request being called, so perform security checking if (fi.getRequest() != null) { fi.getRequest().setAttribute(FILTER_APPLIED, Boolean.TRUE); } #1. before invocation重要 InterceptorStatusToken token = super.beforeInvocation(fi); try { #2. 可以理解开始请求真正的 /persons 服务 fi.getChain().doFilter(fi.getRequest(), fi.getResponse()); } finally { super.finallyInvocation(token); } #3. after Invocation super.afterInvocation(token, null); } } 复制代码 before invocation重要 请求真正的 /persons 服务 after Invocation三个部分中，最重要的是 #1，该过程中会调用 AccessDecisionManager 来验证当前已认证成功的用户是否有权限访问该资源；
AccessDecisionManager: beforeInvocation protected InterceptorStatusToken beforeInvocation(Object object) { ... Collection<ConfigAttribute> attributes = this.obtainSecurityMetadataSource() .getAttributes(object); ... Authentication authenticated = authenticateIfRequired(); // Attempt authorization try { #1.重点 this.accessDecisionManager.decide(authenticated, object, attributes); } catch (AccessDeniedException accessDeniedException) { publishEvent(new AuthorizationFailureEvent(object, attributes, authenticated,accessDeniedException)); throw accessDeniedException; } ... } 复制代码authenticated 就是当前认证的 Authentication ，那么object 和attributes又是什么呢？
attributes和object 是什么？ Collection<ConfigAttribute> attributes = this.obtainSecurityMetadataSource() .getAttributes(object); 复制代码调试
我们发现 object 为当前请求的 url:/persons , 那么 getAttributes
方法就是使用当前的访问资源路径去匹配我们自己定义的匹配规则。
protected void configure(HttpSecurity http) throws Exception { http.formLogin()//使用表单登录，不再使用默认httpBasic方式 .loginPage(SecurityConstants.DEFAULT_UNAUTHENTICATION_URL)//如果请求的URL需要认证则跳转的URL .loginProcessingUrl(SecurityConstants.DEFAULT_SIGN_IN_PROCESSING_URL_FORM)//处理表单中自定义的登录URL .and() .authorizeRequests().antMatchers(SecurityConstants.DEFAULT_UNAUTHENTICATION_URL, SecurityConstants.DEFAULT_SIGN_IN_PROCESSING_URL_FORM, SecurityConstants.DEFAULT_REGISTER_URL, "/**/*.js", "/**/*.css", "/**/*.jpg", "/**/*.png", "/**/*.woff2") .permitAll()//以上的请求都不需要认证 .anyRequest()//剩下的请求 .authenticated()//都需要认证 .and() .csrf().disable()//关闭csrd拦截 ; } 复制代码0-7 返回 permitALL 即不需要认证 , 8 对应 anyRequest 返回 authenticated 即当前请求需要认证;
可以看到当前的 authenticated 为匿名 AnonymousAuthentication 用户名为 anonymousUser AccessDecisionManager 是如何授权的？
Spring Security默认使用 AffirmativeBased 实现 AccessDecisionManager 的 decide 方法来实现授权
public void decide(Authentication authentication, Object object, Collection<ConfigAttribute> configAttributes) throws AccessDeniedException { int deny = 0; #1.调用AccessDecisionVoter 进行vote(投票) for (AccessDecisionVoter voter : getDecisionVoters()) { int result = voter.vote(authentication, object, configAttributes); if (logger.isDebugEnabled()) { logger.debug("Voter: " + voter + ", returned: " + result); } switch (result) { #1.1只要有voter投票为ACCESS_GRANTED，则通过 直接返回 case AccessDecisionVoter.ACCESS_GRANTED://1 return; @#1.2只要有voter投票为ACCESS_DENIED，则记录一下 case AccessDecisionVoter.ACCESS_DENIED://-1 deny++; break; default: break; } } if (deny > 0) { #2.如果有两个及以上AccessDecisionVoter(姑且称之为投票者吧)都投ACCESS_DENIED，则直接就不通过了 throw new AccessDeniedException(messages.getMessage( "AbstractAccessDecisionManager.accessDenied", "Access is denied")); } // To get this far, every AccessDecisionVoter abstained checkAllowIfAllAbstainDecisions(); } 复制代码 调用AccessDecisionVoter 进行vote(投票) 只要有投通过（ACCESS_GRANTED）票，则直接判为通过。 如果没有投通过则 deny++ ,最后判断if（deny>0 抛出AccessDeniedException（未授权） WebExpressionVoter.vote() public int vote(Authentication authentication, FilterInvocation fi, Collection<ConfigAttribute> attributes) { assert authentication != null; assert fi != null; assert attributes != null; WebExpressionConfigAttribute weca = findConfigAttribute(attributes); if (weca == null) { return ACCESS_ABSTAIN; } EvaluationContext ctx = expressionHandler.createEvaluationContext(authentication, fi); ctx = weca.postProcess(ctx, fi); return ExpressionUtils.evaluateAsBoolean(weca.getAuthorizeExpression(), ctx) ? ACCESS_GRANTED : ACCESS_DENIED; } 复制代码到此位置 authentication 当前用户信息， fl 当前访问的资源路径及 attributes 当前资源路径的决策（即是否需要认证）。剩下就是判断当前用户的角色 Authentication.authorites 是否权限访问决策访问当前资源fi。
