cas5.3.14的login-webflow.xml分析

<?xml version="1.0" encoding="UTF-8"?>
<flow xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
      xmlns="http://www.springframework.org/schema/webflow"
      xsi:schemaLocation="http://www.springframework.org/schema/webflow
                          http://www.springframework.org/schema/webflow/spring-webflow.xsd">
    <action-state id="initializeLoginForm">
        <evaluate expression="initializeLoginAction" />
        <transition on="success" to="viewLoginForm"/>
    </action-state>

    <view-state id="viewLoginForm" view="casLoginView" model="credential">
        <binder>
            <binding property="username" required="true"/>
            <binding property="password" required="true"/>
        </binder>
        <transition on="submit" bind="true" validate="true" to="realSubmit" history="invalidate"/>
    </view-state>

    <action-state id="realSubmit">
        <evaluate expression="authenticationViaFormAction"/>
        <transition on="warn" to="warn"/>
        <transition on="success" to="createTicketGrantingTicket"/>
        <transition on="successWithWarnings" to="showAuthenticationWarningMessages"/>
        <transition on="authenticationFailure" to="handleAuthenticationFailure"/>
        <transition on="error" to="initializeLoginForm"/>
    </action-state>
    <end-state id=""/>

</flow>

首先说明一下，expression的值：可以有两种，一种是调用pojo的方法，一种是调用flow的Action，或者是实现multiAction的类 ，在文档中有说明 

登录成功后，在调用 authenticationViaFormAction进行一系列的验证后，会有返回值，根据返回值 在transition中配置，然后跳转，to后面跟着的应该是一个state的id,但是却没有找到createTicketGrantingTicket 的state。然后去跟源码,原来这个state是在配置文件中使用程序创建的，并不xml的配置中，源码如下：在DefaultLoginWebflowConfigurer配置文件中可以rh看到，创建了一个action-state，并且设置了两个transition,成功会跳转到sendTicketGrantingTicket

 /**
     * Create create ticket granting ticket action.
     *
     * @param flow the flow
     */
    protected void createCreateTicketGrantingTicketAction(final Flow flow) {
        final ActionState action = createActionState(flow, CasWebflowConstants.STATE_ID_CREATE_TICKET_GRANTING_TICKET,
            CasWebflowConstants.ACTION_ID_CREATE_TICKET_GRANTING_TICKET);
        createTransitionForState(action, CasWebflowConstants.TRANSITION_ID_SUCCESS, CasWebflowConstants.STATE_ID_SEND_TICKET_GRANTING_TICKET);
        createTransitionForState(action, CasWebflowConstants.TRANSITION_ID_SUCCESS_WITH_WARNINGS, CasWebflowConstants.VIEW_ID_SHOW_AUTHN_WARNING_MSGS);
    }

在创建action-state的方法可以看到

    @Override
    public ActionState createActionState(final Flow flow, final String name, final Action... actions) {
        if (containsFlowState(flow, name)) {
            LOGGER.debug("Flow [{}] already contains a definition for state id [{}]", flow.getId(), name);
            return getTransitionableState(flow, name, ActionState.class);
        }
        final ActionState actionState = new ActionState(flow, name);
        LOGGER.debug("Created action state [{}]", actionState.getId());
        actionState.getActionList().addAll(actions);
        LOGGER.debug("Added action to the action state [{}] list of actions: [{}]", actionState.getId(), actionState.getActionList());
        return actionState;
    }

   /**
     * Create action state action state.
     *
     * @param flow   the flow
     * @param name   the name
     * @param action the action
     * @return the action state
     */
    public ActionState createActionState(final Flow flow, final String name, final String action) {
        return createActionState(flow, name, createEvaluateAction(action));
    }

然后进入，createEvaluateAction可以看到

   @Override
    public EvaluateAction createEvaluateAction(final String expression) {
        if (this.flowBuilderServices == null) {
            LOGGER.error("Flow builder services is not configured correctly.");
            return null;
        }
        final ParserContext ctx = new FluentParserContext();
        final Expression action = this.flowBuilderServices.getExpressionParser().parseExpression(expression, ctx);
        final EvaluateAction newAction = new EvaluateAction(action, null);
        LOGGER.debug("Created evaluate action for expression [{}]", action.getExpressionString());
        return newAction;
    }

这里是为刚才创建的action-state创建了一个evaluate,expression是createTicketGrantingTicketAction,到这为止就可以明白，

        <transition on="success" to="createTicketGrantingTicket"/>这句最终其实是去调用了createTicketGrantingTicketAction，在这个类中的doExecute方法有具体的业务逻辑，来生成tgt

    /**                                  
     * Due to a bug in mod-auth-cas and possibly other clients in the way tickets are parsed,
     * the ticket id body is sanitized to remove the character "_", replacing it with "-" instead.
     * This might be revisited in the future and removed, once at least mod-auth-cas fixes
     * the issue.
     * @param prefix The prefix we want attached to the ticket.
     * @return the ticket id
     */
    @Override
    public String getNewTicketId(final String prefix) {
        final String number = this.numericGenerator.getNextNumberAsString();
        final String ticketBody = this.randomStringGenerator.getNewString().replace('_', '-');
        return prefix + '-' + number + '-' + ticketBody + StringUtils.defaultString(this.suffix);
    }

。