Spring Web Flow :流程,基于Spring MVC 的DispatchServlet

使用方法

• 配置命名空間,目前不支持java方式的配置

<?xml version="1.0" encoding="UTF-8"?>
<flow xmlns="http://www.springframework.org/schema/beans"
      xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
      xmlns="http://www.springframework.org/schema/webflow"
      xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/webflow
                          http://www.springframework.org/schema/webflow/spring-webflow.xsd">

• 流程執行器,負責創建和執行流程執行器webflowContext.xml

    <webflow:flow-executor id="logoutFlowExecutor" flow-registry="logoutFlowRegistry">
        <webflow:flow-execution-attributes>
            <webflow:always-redirect-on-pause value="false"/>
            <webflow:redirect-in-same-state value="false"/>
        </webflow:flow-execution-attributes>
    </webflow:flow-executor>

• 配置流程注冊器,加載流程定義,并讓執行器能夠使用它們.webflowContext.xml

    <webflow:flow-registry id="logoutFlowRegistry" flow-builder-services="builder" base-path="/WEB-INF/webflow">
        <webflow:flow-location-pattern value="/logout/*-webflow.xml"/>
    </webflow:flow-registry>

也可以用 <webflow:flow-location path=""/>指定一個絕對路徑,而不用webflow:flow-location-pattern 和base-path

• 配置服務構造器webflowContext.xml

    <webflow:flow-builder-services id="builder"
                                   development="true"
                                   view-factory-creator="viewFactoryCreator"
                                   expression-parser="expressionParser"/>

• 處理流程請求cas-servlet.xml
FlowHandlerMapping 幫助DispatchServlet將請求發送給Spring Web Flow

    <!-- logout webflow configuration -->
    <bean id="logoutFlowHandlerMapping" class="org.springframework.webflow.mvc.servlet.FlowHandlerMapping"
          p:flowRegistry-ref="logoutFlowRegistry" p:order="3">
        <property name="interceptors">
            <array value-type="org.springframework.web.servlet.HandlerInterceptor">
                <ref bean="localeChangeInterceptor"/>
            </array>
        </property>
    </bean>

FlowHandlerMapping的工作僅僅是將請求重定向給 Spring Web Flow
響應請求的是FlowHandlerAdapter 等同于Spring MVC的控制器,處理請求.配置如下:cas-servlet.xml

    <bean id="logoutHandlerAdapter" class="org.jasig.cas.web.flow.SelectiveFlowHandlerAdapter"
          p:supportedFlowId="logout" p:flowExecutor-ref="logoutFlowExecutor"
          p:flowUrlHandler-ref="logoutFlowUrlHandler"/>

    <bean id="logoutFlowUrlHandler" class="org.jasig.cas.web.flow.CasDefaultFlowUrlHandler"
          p:flowExecutionKeyParameter="RelayState"/>

流程的組件

如果流程是旅行,那么狀態就是路途上的城鎮,風景點,轉移就是公路,流程數據就像一路買的紀念品和記憶

• 狀態

• 視圖狀態:

 <view-state id="redirectToFrontApp" view="externalRedirect:#{currentEvent.attributes.logoutUrl}&amp;RelayState=#{flowExecutionContext.key}">
   <transition on="next" to="frontLogout" />
 </view-state>

屬性解釋
id:在流程內標識這個狀態,(邏輯視圖名)
view:展現的邏輯視圖名
model:表單所綁定的對象

    <view-state id="viewLoginForm" view="casLoginView" model="credential" >
        <binder>
            <binding property="username" required="true" />
            <binding property="password" required="true"/>
            <binding property="captcha"/>
            <!--
            <binding property="rememberMe" />
            -->
        </binder>
        <on-entry>
            <set name="viewScope.commandName" value="'credential'"/>

            <!--
            <evaluate expression="samlMetadataUIParserAction" />
            -->
        </on-entry>
<!--         <transition on="submit" bind="true" validate="true" to="realSubmit"/> -->
        <transition on="submit" bind="true" validate="true" to="validate"/>
    </view-state>

• 行為狀態
  例子:

  <action-state id="frontLogout">
    <evaluate expression="frontChannelLogoutAction" />
    <transition on="finish" to="finishLogout" />
    <transition on="redirectApp" to="redirectToFrontApp" />
  </action-state>
或
    <action-state id="validate">
        <evaluate expression="captchaVaditeAuthenticationViaFormAction.validate(flowRequestContext, flowScope.credential, messageContext)"/>
        <transition on="error" to="initializeLogin"/>
        <transition on="valid" to="realSubmit"/>
    </action-state>

屬性解釋:
evaluate:行為狀態要做的事情
expression : 調用那個Action,并計算結果.用SpEL表達式

• 決策狀態
  決定分支

    <decision-state id="serviceCheck">
        <if test="flowScope.service != null" then="generateServiceTicket" else="viewGenericLoginSuccess"/>
    </decision-state>

test是SpEL表達式,返回結果必須是Boolean格式,可以調指定bean(一般是Action)中的一個方法.

• 子流程狀態

<subflow-state id="order" subflow="pizza/order">
   <input name="order" value="order"/>
   <transition on="orderCreated" to=" payment" /> 
</subflow-state>

• 結束狀態

<end-state id="redirectView" view="externalRedirect:#{requestScope.response.url}"/>
或
<end-state id="viewRedirectToUnauthorizedUrlView" view="externalRedirect:#{flowScope.unauthorizedRedirectUrl}"/>

view:如果是externalRedirect:前綴,將重定向到流程的外部頁面;如果是flowRedirect:前綴,將重定向到另一個流程中

• 轉移

    <transition on="finish" to="finishLogout" />
    <transition on="front" to="frontLogout" />

Action中返回的寫法

       if (needFrontSlo) {
           return new Event(this, FRONT_EVENT);
       } else {
           // otherwise, finish the logout process
           return new Event(this, FINISH_EVENT);
       }

如果只有to屬性,則是默認的轉移狀態
異常轉移

<transition to="viewServiceErrorView"
                    on-exception="org.springframework.webflow.execution.repository.NoSuchFlowExecutionException"/>

全局轉移 將重復寫的共用的轉移抽取出來

    <global-transitions>
        <transition to="viewLoginForm" on-exception="org.jasig.cas.services.UnauthorizedSsoServiceException"/>
        <transition to="viewServiceErrorView"
                    on-exception="org.springframework.webflow.execution.repository.NoSuchFlowExecutionException"/>
        <transition to="serviceUnauthorizedCheck" on-exception="org.jasig.cas.services.UnauthorizedServiceException"/>
        <transition to="serviceUnauthorizedCheck" on-exception="org.jasig.cas.services.UnauthorizedServiceForPrincipalException" />
    </global-transitions>

• 流程數據

• 聲明變量

<var name="credential" class="org.jasig.cas.authentication.RememberMeUsernamePasswordCredential" />
或
<evaluate result="viewScope.toppingsList" expression="T(com.springinaction.pizza.domain.Topping).asList()"/>
#viewScope 視圖作用域
或
<set name="flowScope.pizza" value="new com.springinaction.pizza.domain.Pizza()"/>
#flowScope 流程作用域

var定義的可以在流程的任意狀態訪問.
作用域

1. flowScope
2. requestParameters
3. flowRequestContext
4. requestScope
5. requestScope.response.responseType.name() == 'POST'"

開始狀態:默認是第一個流程定義文件中的第一個狀態,也可以用 start-state

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

            <input type="hidden" name="execution" value="${flowExecutionKey}" />
            <input type="hidden" name="_eventId" value="submit" />

-### 實例

-### 保護Web流程

<view-state id="restricted"> <secured attributes="ROLE_ADMIN" match="all"/>
</view-state>

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