首先Spring Security的认证功能是依赖Filter实现的，当然在认证功能基础上还提供了一些安全的验证等都是依赖Filter来实现完成的，如下截图Spring Security提供了13个功能Filter，并且是按照如下顺序依次执行的。当然配合Spring web的Filter注入实现，Spring Security提供了另外一个Filter的实现类FilterChainProxy，其对外包装了以下13个Filter，其实13个Filter是在接口SecurityFilterChain的实现类DefaultSecurityFilterChain中通过List保存的。
接下来我们依次介绍一下这个13个Filter。
1、WebAsyncManagerIntegrationFilter
接下来我们依次介绍一下这个13个Filter。
1、WebAsyncManagerIntegrationFilter
public final class WebAsyncManagerIntegrationFilter extends OncePerRequestFilter {
private static final Object CALLABLE_INTERCEPTOR_KEY = new Object();
@Override
protected void doFilterInternal(HttpServletRequest request,
HttpServletResponse response, FilterChain filterChain)
throws ServletException, IOException {
WebAsyncManager asyncManager = WebAsyncUtils.getAsyncManager(request);
SecurityContextCallableProcessingInterceptor securityProcessingInterceptor = (SecurityContextCallableProcessingInterceptor) asyncManager
.getCallableInterceptor(CALLABLE_INTERCEPTOR_KEY);
if (securityProcessingInterceptor == null) {
asyncManager.registerCallableInterceptor(CALLABLE_INTERCEPTOR_KEY,
new SecurityContextCallableProcessingInterceptor());
}
filterChain.doFilter(request, response);
}
}
根据请求封装获取WebAsyncManager
从WebAsyncManager获取/注册SecurityContextCallableProcessingInterceptor
2、SecurityContextPersistenceFilter
两个主要职责：请求来临时，创建SecurityContext安全上下文信息，请求结束时清空SecurityContextHolder。
public class SecurityContextPersistenceFilter extends GenericFilterBean {
static final String FILTER_APPLIED = "__spring_security_scpf_applied";
private SecurityContextRepository repo;
private boolean forceEagerSessionCreation = false;
public SecurityContextPersistenceFilter() {
this(new HttpSessionSecurityContextRepository());
}
public SecurityContextPersistenceFilter(SecurityContextRepository repo) {
this.repo = repo;
}
public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain)
throws IOException, ServletException {
HttpServletRequest request = (HttpServletRequest) req;
HttpServletResponse response = (HttpServletResponse) res;
//判断是否已经处理过
if (request.getAttribute(FILTER_APPLIED) != null) {
// ensure that filter is only applied once per request
chain.doFilter(request, response);
return;
}
final boolean debug = logger.isDebugEnabled();
request.setAttribute(FILTER_APPLIED, Boolean.TRUE);
if (forceEagerSessionCreation) {
HttpSession session = request.getSession();
if (debug && session.isNew()) {
logger.debug("Eagerly created session: " + session.getId());
}
}
HttpRequestResponseHolder holder = new HttpRequestResponseHolder(request,
response);
//获取SecurityContext
SecurityContext contextBeforeChainExecution = repo.loadContext(holder);
try {
SecurityContextHolder.setContext(contextBeforeChainExecution);
chain.doFilter(holder.getRequest(), holder.getResponse());
}
finally {
//结束后清理SecurityContext
SecurityContext contextAfterChainExecution = SecurityContextHolder
.getContext();
// Crucial removal of SecurityContextHolder contents - do this before anything
// else.
SecurityContextHolder.clearContext();
repo.saveContext(contextAfterChainExecution, holder.getRequest(),
holder.getResponse());
request.removeAttribute(FILTER_APPLIED);
if (debug) {
logger.debug("SecurityContextHolder now cleared, as request processing completed");
}
}
}
public void setForceEagerSessionCreation(boolean forceEagerSessionCreation) {
this.forceEagerSessionCreation = forceEagerSessionCreation;
}
}
3、HeaderWriterFilter
用来给http响应添加一些Header,比如X-Frame-Options, X-XSS-Protection*，X-Content-Type-Options.
public class HeaderWriterFilter extends OncePerRequestFilter {
/**
* Collection of {@link HeaderWriter} instances to write out the headers to the
* response.
*/
private final List<HeaderWriter> headerWriters;
/**
* Creates a new instance.
*
* @param headerWriters the {@link HeaderWriter} instances to write out headers to the
* {@link HttpServletResponse}.
*/
public HeaderWriterFilter(List<HeaderWriter> headerWriters) {
Assert.notEmpty(headerWriters, "headerWriters cannot be null or empty");
this.headerWriters = headerWriters;
}
@Override
protected void doFilterInternal(HttpServletRequest request,
HttpServletResponse response, FilterChain filterChain)
throws ServletException, IOException {
HeaderWriterResponse headerWriterResponse = new HeaderWriterResponse(request,
response, this.headerWriters);
try {
filterChain.doFilter(request, headerWriterResponse);
}
finally {
headerWriterResponse.writeHeaders();
}
}
static class HeaderWriterResponse extends OnCommittedResponseWrapper {
private final HttpServletRequest request;
private final List<HeaderWriter> headerWriters;
HeaderWriterResponse(HttpServletRequest request, HttpServletResponse response,
List<HeaderWriter> headerWriters) {
super(response);
this.request = request;
this.headerWriters = headerWriters;
}
/*
* (non-Javadoc)
*
* @see org.springframework.security.web.util.OnCommittedResponseWrapper#
* onResponseCommitted()
*/
@Override
protected void onResponseCommitted() {
writeHeaders();
this.disableOnResponseCommitted();
}
protected void writeHeaders() {
if (isDisableOnResponseCommitted()) {
return;
}
for (HeaderWriter headerWriter : this.headerWriters) {
headerWriter.writeHeaders(this.request, getHttpResponse());
}
}
private HttpServletResponse getHttpResponse() {
return (HttpServletResponse) getResponse();
}
}
}
4、LogoutFilter
退出拦截器，退出的简单操作就是删除Session，根据Spring Security初始化配置的退出地址来匹配请求。
public class LogoutFilter extends GenericFilterBean {
// ~ Instance fields
// ================================================================================================
private RequestMatcher logoutRequestMatcher;
private final List<LogoutHandler> handlers;
private final LogoutSuccessHandler logoutSuccessHandler;
// ~ Constructors
// ===================================================================================================
/**
* Constructor which takes a <tt>LogoutSuccessHandler</tt> instance to determine the
* target destination after logging out. The list of <tt>LogoutHandler</tt>s are
* intended to perform the actual logout functionality (such as clearing the security
* context, invalidating the session, etc.).
*/
public LogoutFilter(LogoutSuccessHandler logoutSuccessHandler,
LogoutHandler... handlers) {
Assert.notEmpty(handlers, "LogoutHandlers are required");
this.handlers = Arrays.asList(handlers);
Assert.notNull(logoutSuccessHandler, "logoutSuccessHandler cannot be null");
this.logoutSuccessHandler = logoutSuccessHandler;
setFilterProcessesUrl("/logout");
}
public LogoutFilter(String logoutSuccessUrl, LogoutHandler... handlers) {
Assert.notEmpty(handlers, "LogoutHandlers are required");
this.handlers = Arrays.asList(handlers);
Assert.isTrue(
!StringUtils.hasLength(logoutSuccessUrl)
|| UrlUtils.isValidRedirectUrl(logoutSuccessUrl),
logoutSuccessUrl + " isn't a valid redirect URL");
SimpleUrlLogoutSuccessHandler urlLogoutSuccessHandler = new SimpleUrlLogoutSuccessHandler();
if (StringUtils.hasText(logoutSuccessUrl)) {
urlLogoutSuccessHandler.setDefaultTargetUrl(logoutSuccessUrl);
}
logoutSuccessHandler = urlLogoutSuccessHandler;
setFilterProcessesUrl("/logout");
}
// ~ Methods
// ========================================================================================================
public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain)
throws IOException, ServletException {
HttpServletRequest request = (HttpServletRequest) req;
HttpServletResponse response = (HttpServletResponse) res;
//判断是不是退出请求
if (requiresLogout(request, response)) {
Authentication auth = SecurityContextHolder.getContext().getAuthentication();
if (logger.isDebugEnabled()) {
logger.debug("Logging out user '" + auth
+ "' and transferring to logout destination");
}
for (LogoutHandler handler : handlers) {
//在logoutHandler中进行删除session操作
handler.logout(request, response, auth);
}
logoutSuccessHandler.onLogoutSuccess(request, response, auth);
return;
}
chain.doFilter(request, response);
}
/**
* Allow subclasses to modify when a logout should take place.
*
* @param request the request
* @param response the response
*
* @return <code>true</code> if logout should occur, <code>false</code> otherwise
*/
protected boolean requiresLogout(HttpServletRequest request,
HttpServletResponse response) {
return logoutRequestMatcher.matches(request);
}
public void setLogoutRequestMatcher(RequestMatcher logoutRequestMatcher) {
Assert.notNull(logoutRequestMatcher, "logoutRequestMatcher cannot be null");
this.logoutRequestMatcher = logoutRequestMatcher;
}
public void setFilterProcessesUrl(String filterProcessesUrl) {
this.logoutRequestMatcher = new AntPathRequestMatcher(filterProcessesUrl);
}
}
当判断请求是退出时，会调用LogoutHandler的logout删除session，具体实现在SecurityContextLogoutHandler的logout方法中。
public void logout(HttpServletRequest request, HttpServletResponse response,
Authentication authentication) {
Assert.notNull(request, "HttpServletRequest required");
if (invalidateHttpSession) {
//设置session无效
HttpSession session = request.getSession(false);
if (session != null) {
logger.debug("Invalidating session: " + session.getId());
session.invalidate();
}
}
if (clearAuthentication) {
SecurityContext context = SecurityContextHolder.getContext();
context.setAuthentication(null);
}
//清理信息
SecurityContextHolder.clearContext();
}
5、UsernamePasswordAuthenticationFilter
用户名和密码校验Filter，是特别重要的一个Filter，我们会在用户登录验证博客中专门进行分析学习一下，当然这个Filter只会对配置的登录请求/login进行业务处理，其他请求不做任何业务处理，其处理逻辑在父类AbstractAuthenticationProcessingFilter中。
public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain)
throws IOException, ServletException {
HttpServletRequest request = (HttpServletRequest) req;
HttpServletResponse response = (HttpServletResponse) res;
//首先判断是不是登录请求，不是登录请求则直接跳过
if (!requiresAuthentication(request, response)) {
chain.doFilter(request, response);
return;
}
//是登录请求进行校验工作
//省略部分代码
authResult = attemptAuthentication(request, response);
//省略部分代码
}
6、DefaultLoginPageGeneratingFilter
当是登录地址请求，登录失败请求或者登出请求则跳转到登录页面。
public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain)
throws IOException, ServletException {
HttpServletRequest request = (HttpServletRequest) req;
HttpServletResponse response = (HttpServletResponse) res;
boolean loginError = isErrorPage(request);
boolean logoutSuccess = isLogoutSuccess(request);
//登录请求，登录错误请求或者登出请求则返回登录页面
if (isLoginUrlRequest(request) || loginError || logoutSuccess) {
String loginPageHtml = generateLoginPageHtml(request, loginError,
logoutSuccess);
response.setContentType("text/html;charset=UTF-8");
response.setContentLength(loginPageHtml.length());
response.getWriter().write(loginPageHtml);
return;
}
chain.doFilter(request, response);
}
7、BasicAuthenticationFilter
处理BASIC authentication认证方式，简单理解和UsernamePasswordAuthenticationFilter类似，不过UsernamePasswordAuthenticationFilter是通过表单提交的，而Authorization认证方式是将用户名密码数据添加到请求header中罢了。
@Override
protected void doFilterInternal(HttpServletRequest request,
HttpServletResponse response, FilterChain chain)
throws IOException, ServletException {
final boolean debug = this.logger.isDebugEnabled();
//请求头中获取Authorization
String header = request.getHeader("Authorization");
//如果不存在或者不是以Basic开头直接跳过处理
if (header == null || !header.startsWith("Basic ")) {
chain.doFilter(request, response);
return;
}
//从header中获取相关用户名密码数据进行验证
try {
String[] tokens = extractAndDecodeHeader(header, request);
assert tokens.length == 2;
String username = tokens[0];
if (debug) {
this.logger
.debug("Basic Authentication Authorization header found for user '"
+ username + "'");
}
if (authenticationIsRequired(username)) {
UsernamePasswordAuthenticationToken authRequest = new UsernamePasswordAuthenticationToken(
username, tokens[1]);
authRequest.setDetails(
this.authenticationDetailsSource.buildDetails(request));
Authentication authResult = this.authenticationManager
.authenticate(authRequest);
if (debug) {
this.logger.debug("Authentication success: " + authResult);
}
SecurityContextHolder.getContext().setAuthentication(authResult);
this.rememberMeServices.loginSuccess(request, response, authResult);
onSuccessfulAuthentication(request, response, authResult);
}
}
catch (AuthenticationException failed) {
SecurityContextHolder.clearContext();
if (debug) {
this.logger.debug("Authentication request for failed: " + failed);
}
this.rememberMeServices.loginFail(request, response);
onUnsuccessfulAuthentication(request, response, failed);
if (this.ignoreFailure) {
chain.doFilter(request, response);
}
else {
this.authenticationEntryPoint.commence(request, response, failed);
}
return;
}
chain.doFilter(request, response);
}
8、RequestCacheAwareFilter
内部维护了一个RequestCache，用于缓存request请求
public class RequestCacheAwareFilter extends GenericFilterBean {
private RequestCache requestCache;
public RequestCacheAwareFilter() {
this(new HttpSessionRequestCache());
}
public RequestCacheAwareFilter(RequestCache requestCache) {
Assert.notNull(requestCache, "requestCache cannot be null");
this.requestCache = requestCache;
}
public void doFilter(ServletRequest request, ServletResponse response,
FilterChain chain) throws IOException, ServletException {
HttpServletRequest wrappedSavedRequest = requestCache.getMatchingRequest(
(HttpServletRequest) request, (HttpServletResponse) response);
chain.doFilter(wrappedSavedRequest == null ? request : wrappedSavedRequest,
response);
}
}
9、SecurityContextHolderAwareRequestFilter
此过滤器对ServletRequest进行了一次包装，使得request具有更加丰富的API
public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain)
throws IOException, ServletException {
chain.doFilter(this.requestFactory.create((HttpServletRequest) req,
(HttpServletResponse) res), res);
}
10、AnonymousAuthenticationFilter
匿名身份过滤器，这个过滤器个人认为很重要，需要将它与UsernamePasswordAuthenticationFilter 放在一起比较理解，spring security为了兼容未登录的访问，也走了一套认证流程，只不过是一个匿名的身份。
public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain)
throws IOException, ServletException {
if (SecurityContextHolder.getContext().getAuthentication() == null) {
//创建一个匿名身份
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);
}
protected Authentication createAuthentication(HttpServletRequest request) {
AnonymousAuthenticationToken auth = new AnonymousAuthenticationToken(key,
principal, authorities);
auth.setDetails(authenticationDetailsSource.buildDetails(request));
return auth;
}
11、SessionManagementFilter
和session相关的过滤器，内部维护了一个SessionAuthenticationStrategy，两者组合使用，常用来防止session-fixation protection attack，以及限制同一用户开启多个会话的数量
public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain)
throws IOException, ServletException {
HttpServletRequest request = (HttpServletRequest) req;
HttpServletResponse response = (HttpServletResponse) res;
if (request.getAttribute(FILTER_APPLIED) != null) {
chain.doFilter(request, response);
return;
}
request.setAttribute(FILTER_APPLIED, Boolean.TRUE);
if (!securityContextRepository.containsContext(request)) {
Authentication authentication = SecurityContextHolder.getContext()
.getAuthentication();
if (authentication != null && !trustResolver.isAnonymous(authentication)) {
// The user has been authenticated during the current request, so call the
// session strategy
try {
sessionAuthenticationStrategy.onAuthentication(authentication,
request, response);
}
catch (SessionAuthenticationException e) {
// The session strategy can reject the authentication
logger.debug(
"SessionAuthenticationStrategy rejected the authentication object",
e);
SecurityContextHolder.clearContext();
failureHandler.onAuthenticationFailure(request, response, e);
return;
}
// Eagerly save the security context to make it available for any possible
// re-entrant
// requests which may occur before the current request completes.
// SEC-1396.
securityContextRepository.saveContext(SecurityContextHolder.getContext(),
request, response);
}
else {
// No security context or authentication present. Check for a session
// timeout
if (request.getRequestedSessionId() != null
&& !request.isRequestedSessionIdValid()) {
if (logger.isDebugEnabled()) {
logger.debug("Requested session ID "
+ request.getRequestedSessionId() + " is invalid.");
}
if (invalidSessionStrategy != null) {
invalidSessionStrategy
.onInvalidSessionDetected(request, response);
return;
}
}
}
}
chain.doFilter(request, response);
}
12、ExceptionTranslationFilter
ExceptionTranslationFilter异常转换过滤器位于整个springSecurityFilterChain的后方，用来转换整个链路中出现的异常，将其转化，顾名思义，转化以意味本身并不处理。一般其只处理两大类异常：AccessDeniedException访问异常和AuthenticationException认证异常。这个过滤器非常重要，因为它将Java中的异常和HTTP的响应连接在了一起，这样在处理异常时，我们不用考虑密码错误该跳到什么页面，账号锁定该如何，只需要关注自己的业务逻辑，抛出相应的异常便可。如果该过滤器检测到AuthenticationException，则将会交给内部的AuthenticationEntryPoint去处理，如果检测到AccessDeniedException，需要先判断当前用户是不是匿名用户，如果是匿名访问，则和前面一样运行AuthenticationEntryPoint，否则会委托给AccessDeniedHandler去处理，而AccessDeniedHandler的默认实现，是AccessDeniedHandlerImpl。所以ExceptionTranslationFilter内部的AuthenticationEntryPoint是至关重要的，顾名思义：认证的入口点。
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;
}
//捕捉一些异常处理，身份校验判断错误会抛出异常，由这里处理
catch (Exception ex) {
// Try to extract a SpringSecurityException from the stacktrace
Throwable[] causeChain = throwableAnalyzer.determineCauseChain(ex);
RuntimeException ase = (AuthenticationException) throwableAnalyzer
.getFirstThrowableOfType(AuthenticationException.class, causeChain);
if (ase == null) {
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);
}
}
}
13、FilterSecurityInterceptor
个人理解任务这个拦截器是Spring Security中最重要的，首先这个拦截器就是进行角色相关的处理，也是登录结果是否成功最后一个判断的拦截器，针对不需要认证和需要认证的请求会进行不同的验证处理，同样在登录博客中会对其做的功能进行详细的说明。
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);
}
//在执行请求调用之前进行验证处理
InterceptorStatusToken token = super.beforeInvocation(fi);
try {
fi.getChain().doFilter(fi.getRequest(), fi.getResponse());
}
finally {
super.finallyInvocation(token);
}
super.afterInvocation(token, null);
}
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