Java JSF onchange事件

我有一个JSF应用程序，其中有一个这样的组合框

<script type="text/javascript" defer="defer">
  <!--//--><![CDATA[//><!--
    helpKey = 'APPLICATION_EDIT_DATASOURCE';

    function reapplyStyles() {}

    function selectT(data){
        if(data.status == "begin"){
            $('editForm:selectTypeButton').click();    
        }
    }

   //--><!]]>
</script>

  <h:form id="editForm">
    <h:inputHidden id="id" value="#{applicationObject.objectId}"/>
    <h:inputHidden id="type" value="#{applicationObject.object.type}"/>
    <h:inputHidden id="selectedDSForApp" value="#{applicationObject.selectedDataSourceId}"/>
    <ui:param name="activityDataSource" value="#{applicationObject.selectedDataSourceBean}"/>

    <a4j:outputPanel id="activityDataSourceRulesPanel">
    <h:panelGrid columns="2" columnClasses="padded" rowClasses="padded">

      <h:outputText value="#{msgs.transformation_rule}"/>
      <h:panelGroup>
          <h:selectOneMenu id="dsTransformationRule" value="#{activityDataSource.selectedTransformationRule}"
                           disabled="#{!sp:hasRight(facesContext, 'ManageApplication')}"
                           readonly="#{!sp:hasRight(facesContext, 'ManageApplication')}">
            <f:selectItems value="#{activityDataSource.transformationRules}"/>
          </h:selectOneMenu>
          <ui:fragment rendered="#{sp:hasRight(facesContext, 'ManageRules')}" >
              <input type="button" value="#{msgs.button_ellipsis}" class="ruleEditorBtn"
                     onclick="SailPoint.Rule.Editor.edit($('editForm:dsTransformationRule').value,
                             'ActivityTransformer',
                             $('editForm:refreshActivityDataSourceRulesButton'))" />
          </ui:fragment>
      </h:panelGroup>

      <h:outputText value="#{msgs.correlation_rule}"/>
      <h:panelGroup>
          <h:selectOneMenu id="dsCorrelationRule" value="#{activityDataSource.selectedCorrelationRule}"
                           disabled="#{!sp:hasRight(facesContext, 'ManageApplication')}"
                           readonly="#{!sp:hasRight(facesContext, 'ManageApplication')}">
            <f:selectItems value="#{activityDataSource.correlationRules}"/>
          </h:selectOneMenu>
          <ui:fragment rendered="#{sp:hasRight(facesContext, 'ManageRules')}" >
              <input type="button" value="#{msgs.button_ellipsis}" class="ruleEditorBtn"
                     onclick="SailPoint.Rule.Editor.edit($('editForm:dsCorrelationRule').value,
                             'ActivityCorrelation',
                             $('editForm:refreshActivityDataSourceRulesButton'))" />
          </ui:fragment>
      </h:panelGroup>

      <h:outputText value="#{msgs.activity_data_src_type}"/>
      <h:panelGroup>
        <a4j:outputPanel id="collectorSettings">
          <h:selectOneMenu id="collectorType"
                           value="#{activityDataSource.object.type}"
                           rendered="#{empty activityDataSource.object.id}"
                           disabled="#{!sp:hasRight(facesContext, 'ManageApplication')}"
                           readonly="#{!sp:hasRight(facesContext, 'ManageApplication')}">
                          <!--  onchange="$('editForm:selectTypeButton').click();"> -->
             <f:ajax event="change" 
                    onevent="selectT"
                    execute="@this dsTransformationRule dsCorrelationRule"
                    render="dsTransformationRule dsCorrelationRule"
                    listener="#{activityDataSource.handleCollectorTypeChange}" />
            <f:selectItem itemValue="" itemLabel="#{msgs.select_collector_type}"/>
            <f:selectItems value="#{activityDataSource.collectorTypes}"/>
          </h:selectOneMenu>
          <h:selectOneMenu id="fixedCollectorType" value="#{empty activityDataSource.object.type ? 'None' : activityDataSource.object.type}"
                           rendered="#{not empty activityDataSource.object.id}"
                           disabled="true"
                           readonly="true">
            <f:selectItem itemValue="#{empty activityDataSource.object.type ? 'None' : activityDataSource.object.type}"
                          itemLabel="#{empty activityDataSource.object.type ? msgs.none : activityDataSource.object.type}"/>
          </h:selectOneMenu>
        </a4j:outputPanel>
      </h:panelGroup>
    </h:panelGrid>
    </a4j:outputPanel>

    <a4j:outputPanel id="configSettings">
      <h:messages infoClass="formInfo" warnClass="formWarn" errorClass="formError" fatalClass="formError"/>

      <h:panelGroup  rendered="#{not empty activityDataSource.object.collector}">
        <ui:include src="#{activityDataSource.configPage}"/>
      </h:panelGroup>
    </a4j:outputPanel>
    <h:panelGroup>
      <div class="buttonRow">
        <ui:fragment rendered="#{sp:hasRight(facesContext, 'ManageApplication')}">
          <h:commandButton id="activityDataSourceSave" action="#{activityDataSource.saveAction}" value="#{msgs.button_save}" styleClass="primaryBtn"/>
        </ui:fragment>
        <h:commandButton id="activityDataSourceCancel" action="#{activityDataSource.cancelAction}" value="#{msgs.button_cancel}" styleClass="secondaryBtn"/>
      </div>
    </h:panelGroup>

    <a4j:commandButton id="refreshActivityDataSourceRulesButton"
                       style="display:none"
                       immediate="true"
                       render="activityDataSourceRulesPanel"/>

    <a4j:commandButton id="selectTypeButton" action="#{activityDataSource.selectType}" style="display:none"
                       render="configSettings, collectorSettings"
                       oncomplete="initializeSelectedConfigPage();"/>

  </h:form>

在上面的代码中，我有一个普通的onchange事件&combobox元素id=collectorType上的ajaxonchange事件

在JSF中对同一元素使用两个变更是否有任何限制

---

另外，如何将first-onchange合并到ajax-onchange。

使用

的

onevent

属性，如下所示：

<h:selectOneMenu id="collectorType"
                   value="#{activityDataSource.object.type}"
                   rendered="#{empty activityDataSource.object.id}"
                   disabled="#{!sp:hasRight(facesContext, 'ManageApplication')}"
                   readonly="#{!sp:hasRight(facesContext, 'ManageApplication')}">
     <f:ajax event="change" 
            execute="@this" 
            render="dsTransformationRule dsCorrelationRule"
            listener="#{activityDataSource.handleCollectorTypeChange}" 
            onevent="$('#editForm\\:selectTypeButton').click();"/>
    <f:selectItem itemValue="" itemLabel="#{msgs.select_collector_type}"/>
    <f:selectItems value="#{activityDataSource.collectorTypes}"/>
</h:selectOneMenu>

现在，您的

f:ajax

可以正常地

执行
和
呈现
您的选择菜单，而无需担心多次访问DTO层

<f:ajax event="change" onevent="selectT"
        execute="@this dsTransformationRule dsCorrelationRule"
        render="dsTransformationRule dsCorrelationRule"
        listener="#{activityDataSource.handleCollectorTypeChange}" />



这样，当调用
handleCollectorTypeChange
时，
\u selectedTransformationRule
和
\u selectedCorrelationRule
都将填充上一次选择的值

另一方面，如果您希望在验证或转换阶段，或直接通过在更新模型值阶段之前调用的事件侦听器方法，获取选择菜单
dsTransformationRule
和
dsCorrelationRule
的值，请检查是否有助于从组件获取值

希望这能解决你的问题，或者至少让你走上正确的方向。
这很有效。但我注意到，在调试时，bean中与我要呈现的元素相关的方法被调用了两次。怎么处理？@CODEFISH到底叫了两次什么？你的
render
属性中的那些元素是什么？我已经回答了我的问题。bean类中的这两个方法在更改事件中被调用两次。ajax更改事件位于元素id=collectorType中。@这是预期的CODEFISH，因为您在
执行
和
渲染
中对选择菜单
dsTransformationRule
和
dsCorrelationRule
进行了两次评估。尝试只使用
render
，或者您希望从ajax更改事件的下拉列表中提交值吗？是的，这就是我需要的。我希望“execute”中的这两个id首先被执行，以便它们将填充并获取vale，并为ajax调用提供数据。我该怎么办？我是JSF新手。基本上，我想在选择collectorType组合框时自动填充其他两个组合框，即dsTransformationRule和dsCorrelationRule。我从这些2 bean类方法中得到的组合框的值。
@PostConstuct
public void init() {
    initRules();
    //include another things you want to be initializaed when this page finishes constructing. 
}

private void initRules() {
    ActivityDataSourceDTO dto = getObject();
    if (dto == null)
        return;

    if (_selectedTransformationRule == null)
        _selectedTransformationRule = dto.getTransformationRule();

    if (_selectedCorrelationRule == null)
        _selectedCorrelationRule = dto.getCorrelationRule();
}

//Let the getters do no dto access, so it won't matter if they're called twice on change
public String getSelectedTransformationRule() {
    return _selectedTransformationRule;
}

public String getSelectedCorrelationRule() {
    return _selectedCorrelationRule;
}

<f:ajax event="change" onevent="selectT"
        execute="@this dsTransformationRule dsCorrelationRule"
        render="dsTransformationRule dsCorrelationRule"
        listener="#{activityDataSource.handleCollectorTypeChange}" />