LogoutFilter过滤器对应的类路径为
org.springframework.security.web.authentication.logout.LogoutFilter
通过这个类的源码可以看出,这个类有两个构造函数
- 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;
- }
- 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;
- }
这两个构造函数的参数,是从哪里传递的呢?没错,就是之前解析http标签通过创建LogoutFilter过滤器的bean定义时通过构造参数注入进来的。下面的部分源码为LogoutFilter的bean定义
- public BeanDefinition parse(Element element, ParserContext pc) {
- String logoutUrl = null;
- String successHandlerRef = null;
- String logoutSuccessUrl = null;
- String invalidateSession = null;
- BeanDefinitionBuilder builder = BeanDefinitionBuilder.rootBeanDefinition(LogoutFilter.class);
- if (element != null) {
- //分别解析logout标签的属性
- Object source = pc.extractSource(element);
- builder.getRawBeanDefinition().setSource(source);
- logoutUrl = element.getAttribute(ATT_LOGOUT_URL);
- successHandlerRef = element.getAttribute(ATT_LOGOUT_HANDLER);
- WebConfigUtils.validateHttpRedirect(logoutUrl, pc, source);
- logoutSuccessUrl = element.getAttribute(ATT_LOGOUT_SUCCESS_URL);
- WebConfigUtils.validateHttpRedirect(logoutSuccessUrl, pc, source);
- invalidateSession = element.getAttribute(ATT_INVALIDATE_SESSION);
- }
- if (!StringUtils.hasText(logoutUrl)) {
- logoutUrl = DEF_LOGOUT_URL;
- }
- //向LogoutFilter中注入属性值filterProcessesUrl
- builder.addPropertyValue(“filterProcessesUrl”, logoutUrl);
- if (StringUtils.hasText(successHandlerRef)) {
- if (StringUtils.hasText(logoutSuccessUrl)) {
- pc.getReaderContext().error(“Use “ + ATT_LOGOUT_URL + ” or “ + ATT_LOGOUT_HANDLER + “, but not both”,
- pc.extractSource(element));
- }
- //如果successHandlerRef不为空,就通过构造函数注入到LogoutFilter中
- builder.addConstructorArgReference(successHandlerRef);
- } else {
- // Use the logout URL if no handler set
- if (!StringUtils.hasText(logoutSuccessUrl)) {
- //如果logout-success-url没有定义,则采用默认的/
- logoutSuccessUrl = DEF_LOGOUT_SUCCESS_URL;
- }
- //通过构造函数注入logoutSuccessUrl值
- builder.addConstructorArgValue(logoutSuccessUrl);
- }
- if (!StringUtils.hasText(invalidateSession)) {
- invalidateSession = DEF_INVALIDATE_SESSION;
- }
- //默认Logout的Handler是SecurityContextLogoutHandler
- ManagedList handlers = new ManagedList();
- SecurityContextLogoutHandler sclh = new SecurityContextLogoutHandler();
- if (“true”.equals(invalidateSession)) {
- sclh.setInvalidateHttpSession(true);
- } else {
- sclh.setInvalidateHttpSession(false);
- }
- handlers.add(sclh);
- //如果有remember me服务,需要添加remember的handler
- if (rememberMeServices != null) {
- handlers.add(new RuntimeBeanReference(rememberMeServices));
- }
- //继续将handlers通过构造参数注入到LogoutFilter的bean中
- builder.addConstructorArgValue(handlers);
- return builder.getBeanDefinition();
- }
此时应该能知道,在LogoutFilter的bean实例化时,两个类变量logoutSuccessUrl、List<LogoutHandler> handlers已经通过构造函数注入到LogoutFilter的实例中来了。
接下来,继续看doFilter部分的源码
- public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain)
- throws IOException, ServletException {
- HttpServletRequest request = (HttpServletRequest) req;
- HttpServletResponse response = (HttpServletResponse) res;
- //判断是否需要退出,主要通过请求的url是否是filterProcessesUrl值来识别
- if (requiresLogout(request, response)) {
- //通过SecurityContext实例获取认证信息
- Authentication auth = SecurityContextHolder.getContext().getAuthentication();
- if (logger.isDebugEnabled()) {
- logger.debug(“Logging out user ‘” + auth + “‘ and transferring to logout destination”);
- }
- //循环LogoutHandler处理退出任务
- for (LogoutHandler handler : handlers) {
- handler.logout(request, response, auth);
- }
- //退出成功后,进行redirect操作
- logoutSuccessHandler.onLogoutSuccess(request, response, auth);
- return;
- }
- chain.doFilter(request, response);
- }
这时,可能会产生疑问。上一个过滤器SecurityContextPersistenceFilter不是只产生了一个空的SecurityContext么?就是一个没有认证信息的SecurityContext实例
- Authentication auth = SecurityContextHolder.getContext().getAuthentication();
这个返回的不是null么?产生这个疑问,肯定是被SecurityContextPersistenceFilter过滤器分析时误导的。实际上,每个过滤器只处理自己负责的事情,LogoutFilter只负责拦截j_spring_security_logout这个url(如果没有配置logout的url),其他的url全部跳过。其实退出功能肯定是登录到应用之后才会使用到的,登录对应的Filter肯定会把认证信息添加到SecurityContext中去的,后面再分析。
继续看LogoutHandler是如何处理退出任务的
- for (LogoutHandler handler : handlers) {
- handler.logout(request, response, auth);
- }
这里的handler至少有一个SecurityContextLogoutHandler,
如果有remember me服务,就还有一个Handler。remember me的handler有两种,
如果配置了持久化信息,如(token-repository-ref、data-source-ref属性)这种的handler为:org.springframework.security.web.authentication.rememberme.PersistentTokenBasedRememberMeServices
如果没有配置,那么handler就是:org.springframework.security.web.authentication.rememberme.TokenBasedRememberMeServices
先来看SecurityContextLogoutHandler
- //完成两个任务1.让session失效;2.清除SecurityContext实例
- public void logout(HttpServletRequest request, HttpServletResponse response, Authentication authentication) {
- Assert.notNull(request, “HttpServletRequest required”);
- if (invalidateHttpSession) {
- HttpSession session = request.getSession(false);
- if (session != null) {
- session.invalidate();
- }
- }
- SecurityContextHolder.clearContext();
- }
再来看remember me的handler
1.配置了持久化属性时的handler:PersistentTokenBasedRememberMeServices
- //也完成两个任务1.清除cookie;2.从持久化中清除remember me数据
- public void logout(HttpServletRequest request, HttpServletResponse response, Authentication authentication) {
- super.logout(request, response, authentication);
- if (authentication != null) {
- //如果定义了token-repository-ref属性,则通过依赖的持久化bean清除
- //如果定义了data-source-ref属性,直接通过
- //JdbcTokenRepositoryImpl清除数据,也就是执行delete操作
- tokenRepository.removeUserTokens(authentication.getName());
- }
- }
2.未配置持久化属性的handler:TokenBasedRememberMeServices
这个handler没有覆盖父类的logout方法,所以直接调用父类的logout方法,仅仅清除cookie
退出成功后执行onLogoutSuccess操作,完成redirect
- logoutSuccessHandler.onLogoutSuccess(request, response, auth);
这个语句是直接redirect到logout标签中的logout-success-url属性定义的url
至此,整个logoutFilter任务已经完成了,总结一下,主要任务为
1.从SecurityContext中获取Authentication,然后调用每个handler处理logout
2.退出成功后跳转到指定的url