CAS 浅析 - 服务端登录流程简介(2) - login-webflow.xml简介

CAS 浅析 - 服务端登录流程简介(二) - login-webflow.xml简介
声明：这只是个人见解，不代表官方。

<on-start>    <evaluate expression="initialFlowSetupAction" /></on-start>

首先他的on-start表示流程开始，开始的时候它会到你的cookie中取Ticket信息。当然，如果你没有登录过Ticket信息当然没有。
cas-servlet.xml里面有initialFlowSetupAction的配置。

<bean id="initialFlowSetupAction" />

其中主要的Code如下：

protected Event doExecute(final RequestContext context) throws Exception {        final HttpServletRequest request = WebUtils.getHttpServletRequest(context);        if (!this.pathPopulated) {            final String contextPath = context.getExternalContext().getContextPath();            final String cookiePath = StringUtils.hasText(contextPath) ? contextPath + "/" : "/";            logger.info("Setting path for cookies to: "                + cookiePath);            this.warnCookieGenerator.setCookiePath(cookiePath);            this.ticketGrantingTicketCookieGenerator.setCookiePath(cookiePath);            this.pathPopulated = true;        }        context.getFlowScope().put(            "ticketGrantingTicketId", this.ticketGrantingTicketCookieGenerator.retrieveCookieValue(request));        context.getFlowScope().put(            "warnCookieValue",            Boolean.valueOf(this.warnCookieGenerator.retrieveCookieValue(request)));        final Service service = WebUtils.getService(this.argumentExtractors,            context);        context.getFlowScope().put("service", service);        return result("success");    }

接下是判断用户是否已经登录过（也就是否存在Ticket信息）:

<decision-state id="ticketGrantingTicketExistsCheck"><if test="flowScope.ticketGrantingTicketId neq null" then="hasServiceCheck" else="gatewayRequestCheck" /></decision-state>    <decision-state id="gatewayRequestCheck"><if test="externalContext.requestParameterMap['gateway'] neq '' &amp;&amp; externalContext.requestParameterMap['gateway'] neq null &amp;&amp; flowScope.service neq null" then="gatewayServicesManagementCheck" else="generateLoginTicket" /></decision-state><decision-state id="hasServiceCheck"><if test="flowScope.service != null" then="renewRequestCheck" else="viewGenericLoginSuccess" /></decision-state><decision-state id="renewRequestCheck"><if test="externalContext.requestParameterMap['renew'] neq '' &amp;&amp; externalContext.requestParameterMap['renew'] neq null" then="generateLoginTicket" else="generateServiceTicket" /></decision-state>

如果存在Ticket则表示已经登录过。
1. 如果已经登录，就进行Ticket验证.
  (1)如果Ticket验证成功就跳转到成功页面.
  (2)如果Ticket验证失败,则重新生成Ticket.
2. 如果未登录，就进行网关验证.
  (1)如果网关验证通过就进生成登录的Ticket.
  (2)如果网关验证失败，则返回异常。

以上有两个分支都会汇到了重新生成Ticket.其它的分支则已经完成。
以下讲解重新生成Ticket之后的流程：

<action-state id="generateLoginTicket">        <evaluate expression="generateLoginTicketAction.generate(flowRequestContext)" /><transition on="generated" to="viewLoginForm" /></action-state>    <view-state id="viewLoginForm" view="casLoginView" model="credentials">        <binder>            <binding property="username" />            <binding property="password" />        </binder>        <on-entry>            <set name="viewScope.commandName" value="'credentials'" />        </on-entry><transition on="submit" bind="true" validate="true" to="realSubmit">            <evaluate expression="authenticationViaFormAction.doBind(flowRequestContext, flowScope.credentials)" />        </transition>        </view-state><action-state id="realSubmit">        <evaluate expression="authenticationViaFormAction.submit(flowRequestContext, flowScope.credentials, messageContext)" /><transition on="warn" to="warn" /><transition on="success" to="sendTicketGrantingTicket" /><transition on="error" to="generateLoginTicket" /></action-state><action-state id="sendTicketGrantingTicket">        <evaluate expression="sendTicketGrantingTicketAction" /><transition to="serviceCheck" /></action-state><decision-state id="serviceCheck"><if test="flowScope.service neq null" then="generateServiceTicket" else="viewGenericLoginSuccess" /></decision-state>

重新生成新的Ticket之后，就会跳转到登录页面。
输入登录信息之后进行登录验证，验证通过，则回填Ticket，跳转到成功页面。
验证失败则会重新生成新的Ticket.