AnonymousAuthenticationFilter过滤器对应的类路径为 

org.springframework.security.web.authentication.AnonymousAuthenticationFilter 

AnonymousAuthenticationFilter过滤器是在UsernamePasswordAuthenticationFilter、BasicAuthenticationFilter、RememberMeAuthenticationFilter这些过滤器后面的，所以如果这三个过滤器都没有认证成功，则为当前的SecurityContext中添加一个经过匿名认证的token，但是通过servlet的getRemoteUser等方法是获取不到登录账号的。因为SecurityContextHolderAwareRequestFilter过滤器在AnonymousAuthenticationFilter前面。 

Java代码  

1. //省略了日志部分  
2. public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain)  
3.         throws IOException, ServletException {  
4.     //applyAnonymousForThisRequest永远返回ture  
5.     if (applyAnonymousForThisRequest((HttpServletRequest) req)) {  
6.         //如果当前SecurityContext中没有认证实体  
7.         if (SecurityContextHolder.getContext().getAuthentication() == null) {  
8.             //产生一个匿名认证实体，并保存到SecurityContext中  
9.             SecurityContextHolder.getContext().setAuthentication(createAuthentication((HttpServletRequest) req));  
10.         } else {  
11.         }  
12.     }  
13.   
14.     chain.doFilter(req, res);  
15. }  
16.   
17. protected Authentication createAuthentication(HttpServletRequest request) {  
18.     //产生匿名认证token，注意这里的key、userAttribute是通过解析标签注入的  
19.     AnonymousAuthenticationToken auth = new AnonymousAuthenticationToken(key, userAttribute.getPassword(),  
20.             userAttribute.getAuthorities());  
21.     auth.setDetails(authenticationDetailsSource.buildDetails(request));  
22.   
23.     return auth;  
24. }  

anonymous标签配置为。 

Xml代码  

1. <anonymous granted-authority=“ROLE_ANONYMOUS” enabled=“true” username=“test”/>  

这里username属性容易混淆，username默认为anonymousUser，实际上是注入到UserAttribute的password变量中的。 

granted-authority属性注入到UserAttribute的authorities授权列表