JSF 2.0 中的 UpdateModelException ClassCastException

Question

我有一个带有 ui:repeat 标签的 Facelets 页面，该标签输出 HTML 表的行，并且每行接受用户输入。这有效。我还有使用相同页面和中继器输出的第二组数据（只是不同的数据）。支持此页面的支持 bean 是 ConversationScoped。

<ui:repeat value="#{cloneBuilderBean.pageTemplate}" var="row" varStatus="status">
  <tr>
    <td>#{row.label}</td>
    <td><h:inputText value=#{row.value}/></td>
  </tr>
</ui:repeat>

我遇到的问题是当用户单击 h:commandButton“继续”到下一页时。这实际上只是重新显示当前页面，但中继器的集合已更新为一组新的数据。从我的调试来看，我什至没有到达我的操作方法，该方法应该因单击 commandButton 进入下一页而触发。下面的堆栈跟踪也没有显示任何命中我的代码的迹象。关于如何解决此错误有什么想法吗？

javax.faces.component.UpdateModelException: java.lang.ClassCastException
    at javax.faces.component.UIInput.updateModel(UIInput.java:853)
    at javax.faces.component.UIInput.processUpdates(UIInput.java:735)
    at com.sun.faces.facelets.component.UIRepeat.process(UIRepeat.java:525)
    at com.sun.faces.facelets.component.UIRepeat.processUpdates(UIRepeat.java:748)
    at javax.faces.component.UIForm.processUpdates(UIForm.java:281)
    at javax.faces.component.UIComponentBase.processUpdates(UIComponentBase.java:1242)
    at javax.faces.component.UIComponentBase.processUpdates(UIComponentBase.java:1242)
    at javax.faces.component.UIViewRoot.processUpdates(UIViewRoot.java:1231)
    at com.sun.faces.lifecycle.UpdateModelValuesPhase.execute(UpdateModelValuesPhase.java:78)
    at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101)
    at com.sun.faces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:118)
    at javax.faces.webapp.FacesServlet.service(FacesServlet.java:593)
    at org.apache.catalina.core.StandardWrapper.service(StandardWrapper.java:1539)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:343)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:217)
    at org.primefaces.webapp.filter.FileUploadFilter.doFilter(FileUploadFilter.java:79)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:256)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:217)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:279)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175)
    at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:655)
    at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:595)
    at com.sun.enterprise.web.WebPipeline.invoke(WebPipeline.java:98)
    at com.sun.enterprise.web.PESessionLockingStandardPipeline.invoke(PESessionLockingStandardPipeline.java:91)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:162)
    at org.apache.catalina.connector.CoyoteAdapter.doService(CoyoteAdapter.java:330)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:231)
    at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:174)
    at com.sun.grizzly.http.ProcessorTask.invokeAdapter(ProcessorTask.java:828)
    at com.sun.grizzly.http.ProcessorTask.doProcess(ProcessorTask.java:725)
    at com.sun.grizzly.http.ProcessorTask.process(ProcessorTask.java:1019)
    at com.sun.grizzly.http.DefaultProtocolFilter.execute(DefaultProtocolFilter.java:225)
    at com.sun.grizzly.DefaultProtocolChain.executeProtocolFilter(DefaultProtocolChain.java:137)
    at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:104)
    at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:90)
    at com.sun.grizzly.http.HttpProtocolChain.execute(HttpProtocolChain.java:79)
    at com.sun.grizzly.ProtocolChainContextTask.doCall(ProtocolChainContextTask.java:54)
    at com.sun.grizzly.SelectionKeyContextTask.call(SelectionKeyContextTask.java:59)
    at com.sun.grizzly.ContextTask.run(ContextTask.java:71)
    at com.sun.grizzly.util.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:532)
    at com.sun.grizzly.util.AbstractThreadPool$Worker.run(AbstractThreadPool.java:513)
    at java.lang.Thread.run(Thread.java:662)
Caused by: java.lang.ClassCastException
    at javax.el.ArrayELResolver.setValue(ArrayELResolver.java:257)
    at com.sun.faces.el.DemuxCompositeELResolver._setValue(DemuxCompositeELResolver.java:255)
    at com.sun.faces.el.DemuxCompositeELResolver.setValue(DemuxCompositeELResolver.java:281)
    at com.sun.el.parser.AstValue.setValue(AstValue.java:197)
    at com.sun.el.ValueExpressionImpl.setValue(ValueExpressionImpl.java:286)
    at org.jboss.weld.el.WeldValueExpression.setValue(WeldValueExpression.java:74)
    at com.sun.faces.facelets.el.TagValueExpression.setValue(TagValueExpression.java:131)
    at javax.faces.component.UIInput.updateModel(UIInput.java:818)
    ... 41 more

---

更新：相关的bean代码是这样的：

private int[] part1,part2;
private int[] currentPart; //pointer to part1 or part2
private List<SelectItem> pageTemplate;

public String openItem(String value){
    conversation.begin();

    //database dummy data...
    pageTemplate = new ArrayList(4);
    pageTemplate.add(new SelectItem("Data1"));
    pageTemplate.add(new SelectItem("Data2"));
    pageTemplate.add(new SelectItem("Data3"));
    pageTemplate.add(new SelectItem("Data4"));

    //database dummy data...
    part1 = new int[4];
    for(int i = 0; i < part1.length; i++){
        part1[i] = i+1;
    }
    currentPart = part1;

    return "page2";
}

public String next(){
    //database dummy data...
    part2 = new int[4];
    for(int i = 0; i < part2.length; i++){
        part2[i] = i+2;
    }
    currentPart = part2;
    return "page2";
}

相关的视图代码是：

<ui:repeat value="#{CloneBuilderBean.pageTemplate}" var="row" varStatus="status">
    <tr>
        <td>#{row.value}</td>
        <td width="300">
            <h:inputHidden id="val" value="#{CloneBuilderBean.currentPart[status.index]}" />
            <p:slider for="val" step="1" style="width:90%;" minValue="0" maxValue="7" />
        </td>
    </tr>
</ui:repeat>

<h:commandButton value="display part 2" action="#{CloneBuilderBean.next()}"/>

Answer 1

由：java.lang.ClassCastException引起
在 javax.el.ArrayELResolver.setValue(ArrayELResolver.java:257)

我重现了您的问题。事实证明，#{CloneBuilderBean.currentPart[status.index]} 是使用 Integer 而不是 int 设置的。当我用 Integer[] 替换 int[] 时，它对我有用。

当我尝试在 Tomcat 7.0.19 而不是 Glassfish 3.1.1 上重现您的问题时，我从其 EL 解析器中得到了更清晰的异常：

由以下原因引起：java.lang.ClassCastException：无法将 [java.lang.Integer] 类型的对象添加到 [int] 类型的对象数组
在 javax.el.ArrayELResolver.setValue(ArrayELResolver.java:96)