动态动作状态问题

Question

我在使用 Spring Webflow 时遇到问题。我的流程 XML 定义是：

<?xml version="1.0" encoding="UTF-8"?>
<flow xmlns="http://www.springframework.org/schema/webflow"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://www.springframework.org/schema/webflow
        http://www.springframework.org/schema/webflow/spring-webflow-2.0.xsd" parent="changeLang">

    <input name="hash" required="true"/>

    <action-state id="decideAction">
        <set name="flowScope.goTo" value ="verifyActionService.verifyHash(hash)" />
        <transition to="${goTo}" ></transition> 
    </action-state>

    <view-state id="correctVerify" view="registered" model="userAddressesForm">
        <transition on="addPhoneNumber" to="correctVerify">
            <evaluate expression="verifyActionService.addPhoneNumber(userAddressesForm)" />
        </transition>
        <transition on="deletePhoneNumber" to="correctVerify">
            <evaluate expression="verifyActionService.deletePhoneNumber(userAddressesForm, requestParameters.deleteNumber)" />
        </transition>
    </view-state>

    <view-state id="notCorrectVerify" view="register"></view-state>

</flow>

verifyHash 方法返回一个等于“ CorrectVerify”的状态 id，如下所示：

public String verifyHash(String hash) {
    return "correctVerify";
}

当我运行它时，出现如下错误：

at java.lang.Thread.run(Thread.java:662)
Caused by: java.lang.IllegalArgumentException: Cannot find state with id '${goTo}' in flow 'verify' -- Known state ids are 'array<String>['decideAction', 'correctVerify', 'notCorrectVerify', 'start']'
at org.springframework.webflow.engine.Flow.getStateInstance(Flow.java:348)
at org.springframework.webflow.engine.support.DefaultTargetStateResolver.resolveTargetState(DefaultTargetStateResolver.java:60)
at org.springframework.webflow.engine.Transition.execute(Transition.java:217)
at org.springframework.webflow.engine.impl.FlowExecutionImpl.execute(FlowExecutionImpl.java:391)
at org.springframework.webflow.engine.impl.RequestControlContextImpl.execute(RequestControlContextImpl.java:214)
at org.springframework.webflow.engine.TransitionableState.handleEvent(TransitionableState.java:119)

有人可以帮助我吗？

Answer 1

transition 的 to 属性采用字符串文字。如果想要组合字符串文字和 EL，则需要使用模板表达式：

<transition to="#{goTo}"/>

有关两种不同类型表达式的信息可以在 文档的此部分。

另外，您确定需要从服务层返回视图状态名称吗？ 的一般模式是使用 调用方法，然后根据 的结果定义到不同状态的不同转换>...类似于 switch 语句。看看这个部分关于行动状态。