博主之前一直使用了cas客户端进行用户的单点登录操作，决定进行源码分析来看cas的整个流程，以便以后出现了问题还不知道是什么原因导致的
cas主要的形式就是通过过滤器的形式来实现的，来，贴上示例配置：
<listener><listener-class>org.jasig.cas.client.session.SingleSignOutHttpSessionListenerlistener-class>listener> <filter><filter-name>SSO Logout Filterfilter-name><filter-class>org.jasig.cas.client.session.SingleSignOutFilterfilter-class>filter> <filter-mapping> <filter-name>SSO Logout Filterfilter-name> <url-pattern>/*url-pattern>filter-mapping> <filter> <filter-name>SSO Authentication Filterfilter-name> <filter-class>org.jasig.cas.client.authentication.AuthenticationFilterfilter-class> <init-param><param-name>SSOServerUrlparam-name><param-value>/ssoparam-value> init-param> <init-param><param-name>SSOLoginUrlparam-name><param-value>/App.ResourceCloud/Src/index.phpparam-value> init-param> <init-param> <param-name>serverNameparam-name><param-value>http://127.0.0.1:9000param-value> init-param> <init-param><param-name>needAttributeparam-name><param-value>trueparam-value> init-param> <init-param><param-name>excludedURLsparam-name><param-value>/site2\.jspparam-value> init-param>filter><filter-mapping> <filter-name>SSO Authentication Filterfilter-name> <url-pattern>/TyrzLogin/*url-pattern>filter-mapping> <filter> <filter-name>SSO Ticket Validation Filterfilter-name> <filter-class>org.jasig.cas.client.validation.Cas20ProxyReceivingTicketValidationFilterfilter-class> <init-param><param-name>serverNameparam-name> <param-value>http://127.0.0.1:9000param-value> init-param> <init-param><param-name>needAttributeparam-name> <param-value>trueparam-value> init-param> <init-param><param-name>SSOServerUrlPrefixparam-name> <param-value>/ssoparam-value> init-param>filter> <filter-mapping> <filter-name>SSO Ticket Validation Filterfilter-name> <url-pattern>/*url-pattern>filter-mapping>
博主用的不是官方的cas的jar包，是第三方要求的又再次封装的jar包，不过就是属性，获取用户信息的逻辑多了点，其他的还是官方的源码，博主懒 的下载官方的jar在进行一步一步的debug看源码了。
基本配置是添加4个过滤器,请求的时候可以进行拦截进行查看，最后一个是jfinal的开发框架，类似spring，不用管
以上是jetty抓到请求时，进行获取过滤的流程，只关注cas的这四个，里面涉及到了缓存过滤器(节点类型存储)
全部进行路径URL匹配完之后，会获取到需要进行执行的过滤器，SSO Logout Filter->SSO Authentication Filter->SSO Ticket Validation Filter->CAS Assertion Thread Local Filter
那我们就来一个一个看看，每个过滤器都做了哪些事。
SSO Logout Filter，从名字上看，应该是个退出的流程操作。来源码附上：
public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {HttpServletRequest request = (HttpServletRequest)servletRequest; HttpServletResponse response = (HttpServletResponse)servletResponse; //查看请求中是否带有ticket参数 if (!handler.isTokenRequest(request) && !CommonUtils.isNotBlank(request.getParameter("ticket"))) {//如果没有的ticket参数，查看是否是退出请求 if (handler.isLogoutRequest(request)) {if (this.sessionMappingStorage != null && !this.sessionMappingStorage.getClass().equals(HashMapBackedSessionMappingStorage.class)) {//是退出请求，直接销毁session，直接return，不会在执行其他过滤器handler.destroySession(request, response);return;} this.log.trace("Ignoring URI " + request.getRequestURI()); } else {handler.recordSession(request); } ///继续执行下一个执行器 filterChain.doFilter(servletRequest, servletResponse); }
AuthenticationFilter,该过滤器主要做法：
public final void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {String requestedUrl = ((HttpServletRequest)servletRequest).getServletPath(); boolean isExcludedUrl = false; //这里会获取到xml中的排除需要过滤的URL配置 if (this.excludedRequestUrlPatterns != null && this.excludedRequestUrlPatterns.length > 0) {Pattern[] arr$ = this.excludedRequestUrlPatterns; int len$ = arr$.length; for(int i$ = 0; i$ < len$; ++i$) {Pattern p = arr$[i$];if (isExcludedUrl = p.matcher(requestedUrl).matches()) {break;} } } HttpServletRequest request = (HttpServletRequest)servletRequest; HttpServletResponse response = (HttpServletResponse)servletResponse; //如果当前URL是被排除，不需要校验cas单点登录的话，直接跳过当前过滤器，进行下一步 if (this.isIgnoreSSO() && isExcludedUrl) {filterChain.doFilter(request, response); } else {//如果当前不被排除在外，查看白名单URL，也可以直接跳过该过滤器 boolean isWhiteUrl = false; if (this.whiteRequestUrlPatterns != null && this.whiteRequestUrlPatterns.length > 0) {Pattern[] arr$ = this.whiteRequestUrlPatterns;int len$ = arr$.length;for(int i$ = 0; i$ < len$; ++i$) {Pattern p = arr$[i$];if (isWhiteUrl = p.matcher(requestedUrl).matches()) {break;}} } if (isWhiteUrl) {filterChain.doFilter(request, response); } else {//如果都没匹配上，说明该URL是需要进行校验查看的HttpSession session = request.getSession(false);//从session中取出改属性值，查看当前session是否已经认证过了。如果认证过了了，可以跳过该过滤器Assertion assertion = session != null ? (Assertion)session.getAttribute("_const_cas_assertion_") : null;//第一次请求的时候，改对象一定为null，因为没人登录过if (assertion != null) {filterChain.doFilter(request, response);} else {String serviceUrl = this.constructServiceUrl(request, response);String ticket = CommonUtils.safeGetParameter(request, this.getArtifactParameterName());//查看是否session中有_const_cas_gateway_该属性值，第一次登录也没有boolean wasGatewayed = this.gatewayStorage.hasGatewayedAlready(request, serviceUrl);//如果都没有if (!CommonUtils.isNotBlank(ticket) && !wasGatewayed) {String encodedService; //查看是否是cas服务器return回调我们的这个接口请求，该属性值在下面，也就是第一次登录的时候，设置的 if (request.getSession().getAttribute("casreturn") != null) {request.getSession().removeAttribute("casreturn"); if (isExcludedUrl) {filterChain.doFilter(request, response); } else {encodedService = Base64.encodeBase64String(serviceUrl.getBytes()); encodedService = encodedService.replaceAll("[\\s*\t\n\r]", ""); if (!this.SSOLoginUrl.startsWith("https://") && !this.SSOLoginUrl.startsWith("http://")) {this.SSOLoginUrl = this.getServerName() + (this.getServerName().endsWith("/") ? "" : "/") + this.SSOLoginUrl; } //-------------@这里---------------------- //一直以为是所有校验都没有参数后，在下面才是跳转到登录页，，没想到，直接回调了，并没有让用户去登陆，而是在这里才去调用登录页 //让用户去登陆。大坑 response.sendRedirect(CommonUtils.joinUrl(this.SSOLoginUrl, "nextpage=" + encodedService)); } } else {//第一次登录的时候是这里，他会将你xml中的cas服务器地址拼接成login登录地址，我们当前请求的URL编码之后，会被cas登录成功后回调使用 encodedService = this.SSOServerUrl + "/login?service=" + URLEncoder.encode(serviceUrl, "UTF-8") + "&redirect=true"; //并且设置cas服务器回调标识 request.getSession().setAttribute("casreturn", true); //第一次登录的时候，只能到这里了，因为ticket参数，或则session中_const_cas_assertion_属性都没有，只能去cas服务器请求登录， //这里有个坑，，没想到在这里没有直接出现登录页，而是调用cas服务器地址后，直接返回来了，而且会在@那里再去调用登录地址 response.sendRedirect(encodedService); //其他的事情后续就不要再debug了，已经跟我们cas没有啥关系了，博主，debug了半天越看越懵，才发现是服务在做其他的事情， // 我们的登录页面早就已经出现了 }} else {filterChain.doFilter(request, response);}} } } }
上面的还有一个坑，就是，在用户登录成功后，回调我们的地址，第一次并不会带给我们ticket参数，而且还会走
encodedService = this.SSOServerUrl + "/login?service=" + URLEncoder.encode(serviceUrl, "UTF-8") + "&redirect=true";
这个逻辑，并且附上casreturn属性，然后，cas服务器这回才会把ticket参数返回给我们的接口，剩下的就是下一个过滤器的事情了，慢慢来：
好了，这次有ticket了，我们来看下一个过滤器SSO Ticket Validation Filter
public final void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {//这里做了点事，是否为代理，博主没用这个，默认代理为null，返回true if (this.preFilter(servletRequest, servletResponse, filterChain)) {HttpServletRequest request = (HttpServletRequest)servletRequest; HttpServletResponse response = (HttpServletResponse)servletResponse; //获取ticket请求参数 String ticket = CommonUtils.safeGetParameter(request, this.getArtifactParameterName()); //到这里了，分为三种情况， //有ticket，因为你已经登录了，cas服务器登录成功返回给你了，接下来进行校验 //无ticket，可能你没有配置第一个过滤器，溜进来了 //无ticket，ticket已经校验成功后跳转回来了，用户属性已经设置到session中了，所以这次请求没有ticket了，不用去校验 if (CommonUtils.isNotBlank(ticket)) {if (this.log.isDebugEnabled()) {this.log.debug("Attempting to validate ticket: " + ticket);}try {//开始ticket票据校验，这才是这个ticket过滤器真正要做的//constructServiceUrl这个方法不用管，就是拼接一下URL路径，把我的APPID啥的拼接上去//validate做了挺多事，请看下一个类注释，这里先过去(大概逻辑就是去cas服务器验证ticket)Assertion assertion = this.ticketValidator.validate(ticket, this.constructServiceUrl(request, response));if (this.log.isDebugEnabled()) {this.log.debug("Successfully authenticated user: " + assertion.getPrincipal().getName());}//看到这里没有，就是在第一个过滤器进行校验的参数，如果ticket验证成功，就会往request，及session设置属性，该属性就是_const_cas_assertion_//该属性值则是一个用户信息maprequest.setAttribute("_const_cas_assertion_", assertion);if (this.useSession) {request.getSession().setAttribute("_const_cas_assertion_", assertion);}//空方法，不用管this.onSuccessfulValidation(request, response, assertion);//ticket验证成功后，在进行跳转，这次是跳到我们自己的请求地址if (this.redirectAfterValidation) {this.log.debug("Redirecting after successful ticket validation."); response.sendRedirect(this.constructServiceUrl(request, response)); return;}} catch (TicketValidationException var8) {response.setStatus(403);this.log.warn(var8, var8);this.onFailedValidation(request, response);if (this.exceptionOnValidationFailure) {throw new ServletException(var8);}return;} } filterChain.doFilter(request, response); } }
里面的ticket验证逻辑在此：
public Assertion validate(String ticket, String service) throws TicketValidationException {//此处是拼接好要调用的URL ///sso/，该路径是在web.xml中改ticket过滤器进行配置的SSOServerUrlPrefix ///sso/serviceValidate?needAttribute=true&ticket=ST-28699-qdyblKpRwc5LpLk57dRM-&service=http%3A%2F%2F127.0.0.1%3A9000%2Fdsideal_yy%2FdsTyrzLogin%2FssoLogin%3FloginType%3Dweb%26from%3Dew%26appId%3D00000&appKey=00000 String validationUrl = this.constructValidationUrl(ticket, service); if (this.log.isDebugEnabled()) {this.log.debug("Constructing validation url: " + validationUrl); } try {this.log.debug("Retrieving response from server."); //这里不用看，就是发起请求调用上面的接口，查看ticket有效性 String serverResponse = this.retrieveResponseFromServer(new URL(validationUrl), ticket); if (serverResponse == null) {throw new TicketValidationException("The CAS server returned no response."); } else {if (this.log.isDebugEnabled()) {this.log.debug("Server response: " + serverResponse);}//这个不用看了，就是解析返回的cas数据，然后获取里面的用户信息，并封装成mapreturn this.parseResponseFromServer(serverResponse); } } catch (MalformedURLException var5) {throw new TicketValidationException(var5); } }
因为ticket验证成功后并没有直接到下一个过滤器，而是从新请求了一次，这次不会有ticket参数了，因为session中已经有属性了，就在前几个过滤器中进行判断，在都走一次，然后才会到下面这个过滤器
public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {HttpServletRequest request = (HttpServletRequest)servletRequest; HttpSession session = request.getSession(false); Assertion assertion = (Assertion)((Assertion)(session == null ? request.getAttribute("_const_cas_assertion_") : session.getAttribute("_const_cas_assertion_"))); try {//该过滤器的作用就是，把用户对象从session中拿出来，放到AssertionHolder里面，从而在代码中获取对象信息的时候， //直接调用该对象即可 AssertionHolder.setAssertion(assertion); filterChain.doFilter(servletRequest, servletResponse); } finally {AssertionHolder.clear(); } }
至此，cas的登录流程全部走完，不知道大家看懂多少，花了博主大概一天的时间才把源码理解通，ticket返回示例给大家一下，还有代码调用：
失败示例：<cas:serviceResponse xmlns:cas='http://www.yale.edu/tp/cas'> <cas:authenticationFailure code='INVALID_TICKET'> ticket 'ST-28699-qdyblKpRwc5LpLk57dRM-' not recognized cas:authenticationFailure>cas:serviceResponse>成功示例：<cas:serviceResponse xmlns:cas='http://www.yale.edu/tp/cas'> <cas:authenticationSuccess> <cas:user>testcas:user> <cas:attributes><cas:multipleId>test-test-test-test-testcas:multipleId><cas:userId>testcas:userId><cas:loginName>testcas:loginName> cas:attributes> cas:authenticationSuccess>cas:serviceResponse>
代码调用示例：
Assertion assertion = AssertionHolder.getAssertion(); String openId = assertion.getPrincipal().getName(); Map<String, Object> attributes = assertion.getPrincipal().getAttributes(); String userId = attributes.get("userId").toString(); String loginName = attributes.get("loginName").toString(); System.out.println("openId:"+openId); System.out.println("userId:"+userId); System.out.println("loginName:"+loginName);
原创不易，转载请说明出处，谢谢！
