弄清楚为什么在我不希望调用它们时调用JSF getter

时间：2011-08-16 12:52:20

标签： java jsf jsf-2

我正在与jsf 2合作，我遇到了一些我难以解释或理解的行为。

我有几个独立的h:form。

其中一个看起来像这样：

<h:form>
    <h:commandButton value="#{text.General_Wipe_Now}" action="#{bean.doThate}" >
        <f:ajax execute="@form" render="@form" />
    </h:commandButton>
    <h:selectBooleanCheckbox value="#{bean.ignoreErrors}">Ignore Errors</h:selectBooleanCheckbox>
</h:form>

我的问题是，无论何时按下前面提到的按钮，我都会看到其他不相关的bean成员getter（也是其他形式的部分）被调用。 （通过记录）

任何getter都没有业务逻辑，但我会喜欢理解这个原因。 通过打印stacktrace，我确保JSF确实是呼叫他们的人。

您如何建议我按照JSF了解他们被调用的原因？ 可能是什么原因？

谢谢！ 本。

更新

这是由一个正在运行且不应该运行的getter打印的堆栈跟踪。 正如评论中所讨论的那样，在这个问题中包含所有相关的细节是非常复杂的，所以我宁愿自己寻求帮助来找到答案。

java.lang.Exception
    at com.aCompanyName.applicationName.beans.aBean.getSomethingFromBean(CurrentDevice.java:382)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at javax.el.BeanELResolver.getValue(BeanELResolver.java:302)
    at javax.el.CompositeELResolver.getValue(CompositeELResolver.java:175)
    at org.apache.myfaces.el.unified.resolver.FacesCompositeELResolver.getValue(FacesCompositeELResolver.java:142)
    at com.sun.el.parser.AstValue.getValue(AstValue.java:116)
    at com.sun.el.parser.AstValue.getValue(AstValue.java:163)
    at com.sun.el.ValueExpressionImpl.getValue(ValueExpressionImpl.java:219)
    at org.apache.myfaces.view.facelets.el.TagValueExpression.getValue(TagValueExpression.java:85)
    at org.apache.myfaces.view.facelets.component.UIRepeat.getValue(UIRepeat.java:248)
    at org.apache.myfaces.view.facelets.component.UIRepeat.getDataModel(UIRepeat.java:211)
    at org.apache.myfaces.view.facelets.component.UIRepeat._validateAttributes(UIRepeat.java:530)
    at org.apache.myfaces.view.facelets.component.UIRepeat.visitTree(UIRepeat.java:763)
    at javax.faces.component.UIComponent.visitTree(UIComponent.java:797)
    at javax.faces.component.UIComponentBase.visitTree(UIComponentBase.java:992)
    at javax.faces.component.UIComponent.visitTree(UIComponent.java:797)
    at javax.faces.component.UIComponentBase.visitTree(UIComponentBase.java:992)
    at javax.faces.component.UIComponent.visitTree(UIComponent.java:797)
    at javax.faces.component.UIComponentBase.visitTree(UIComponentBase.java:992)
    at javax.faces.component.UIComponent.visitTree(UIComponent.java:797)
    at javax.faces.component.UIComponentBase.visitTree(UIComponentBase.java:992)
    at javax.faces.component.UIComponent.visitTree(UIComponent.java:797)
    at javax.faces.component.UIComponentBase.visitTree(UIComponentBase.java:992)
    at javax.faces.component.UIComponent.visitTree(UIComponent.java:797)
    at javax.faces.component.UIComponentBase.visitTree(UIComponentBase.java:992)
    at javax.faces.component.UIComponent.visitTree(UIComponent.java:797)
    at javax.faces.component.UIComponentBase.visitTree(UIComponentBase.java:992)
    at javax.faces.component.UIComponent.visitTree(UIComponent.java:797)
    at javax.faces.component.UIComponentBase.visitTree(UIComponentBase.java:992)
    at javax.faces.component.UIComponent.visitTree(UIComponent.java:797)
    at javax.faces.component.UIComponentBase.visitTree(UIComponentBase.java:992)
    at javax.faces.component.UIComponent.visitTree(UIComponent.java:797)
    at javax.faces.component.UIComponentBase.visitTree(UIComponentBase.java:992)
    at javax.faces.component.UIComponent.visitTree(UIComponent.java:797)
    at javax.faces.component.UIComponentBase.visitTree(UIComponentBase.java:992)
    at javax.faces.component.UIComponent.visitTree(UIComponent.java:797)
    at javax.faces.component.UIComponentBase.visitTree(UIComponentBase.java:992)
    at org.apache.myfaces.view.facelets.tag.ui.DebugPhaseListener._doTreeVisit(DebugPhaseListener.java:310)
    at org.apache.myfaces.view.facelets.tag.ui.DebugPhaseListener.afterPhase(DebugPhaseListener.java:286)
    at org.apache.myfaces.lifecycle.PhaseListenerManager.informPhaseListenersAfter(PhaseListenerManager.java:111)
    at org.apache.myfaces.lifecycle.LifecycleImpl.executePhase(LifecycleImpl.java:185)
    at org.apache.myfaces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:118)
    at javax.faces.webapp.FacesServlet.service(FacesServlet.java:189)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
    at org.apache.openejb.tomcat.catalina.OpenEJBValve.invoke(OpenEJBValve.java:45)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298)
    at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:852)
    at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:588)
    at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)
    at java.lang.Thread.run(Thread.java:662)

更新2

制作SSCCE，一旦有了SSCCE就会更新。

更新3

<ui:repeat>值属性似乎出现问题。 这是一个SSCCE代码，可以解释这个问题：

<h:body>
    <ui:repeat var="str" value="#{admin.SList}">
        STRING: #{str}
    </ui:repeat>

    <h:form>
        <h:commandButton value="pressie" action="#{admin.doThat}">
            <f:ajax execute="@form"/>
        </h:commandButton>
    </h:form>
</h:body>

Bean Code：

@PostConstruct
public void init()
{
    slist.add("Testing");
    slist.add("This");
    slist.add("Thing");
}

private List<String> slist = new ArrayList<String>();

public List<String> getSList(){
    logger.trace("Getting LIST");
    return slist;
}

public void doThat(){
    logger.trace("DoThat Was Run");
}

按下按钮时，会输出到日志：

2011-08-16 16:55:55,853 TRACE [http-80-2] (AdminBean.java:80) - Getting LIST
2011-08-16 16:55:55,865 TRACE [http-80-2] (AdminBean.java:85) - DoThat Was Run

为什么要运行列表？这不是多余的吗？

1 个答案:

答案 0 :(得分：1)

我不使用MyFaces，所以我不会详细说明。但值得一提的是，在Mojarra上，getter也被称为<ui:repeat>。但是，对于正在发生的事情，堆栈更加清晰。这是Thread#dumpStack()直到FacesServlet#service()：

java.lang.Exception: Stack trace
    at java.lang.Thread.dumpStack(Thread.java:1249)
    at mypackage.Bean.getList(Bean.java:21)
    at sun.reflect.GeneratedMethodAccessor51.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at javax.el.BeanELResolver.getValue(BeanELResolver.java:302)
    at com.sun.faces.el.DemuxCompositeELResolver._getValue(DemuxCompositeELResolver.java:176)
    at com.sun.faces.el.DemuxCompositeELResolver.getValue(DemuxCompositeELResolver.java:203)
    at com.sun.el.parser.AstValue.getValue(AstValue.java:116)
    at com.sun.el.parser.AstValue.getValue(AstValue.java:163)
    at com.sun.el.ValueExpressionImpl.getValue(ValueExpressionImpl.java:219)
    at com.sun.faces.facelets.el.TagValueExpression.getValue(TagValueExpression.java:109)
    at com.sun.faces.facelets.component.UIRepeat.getValue(UIRepeat.java:272)
    at com.sun.faces.facelets.component.UIRepeat.getDataModel(UIRepeat.java:248)
    at com.sun.faces.facelets.component.UIRepeat.setIndex(UIRepeat.java:442)
    at com.sun.faces.facelets.component.UIRepeat.doVisitChildren(UIRepeat.java:661)
    at com.sun.faces.facelets.component.UIRepeat.visitTree(UIRepeat.java:619)
    at javax.faces.component.UIComponent.visitTree(UIComponent.java:1600)
    at javax.faces.component.UIComponent.visitTree(UIComponent.java:1600)
    at com.sun.faces.application.view.StateManagementStrategyImpl.restoreView(StateManagementStrategyImpl.java:240)
    at com.sun.faces.application.StateManagerImpl.restoreView(StateManagerImpl.java:188)
    at com.sun.faces.application.view.ViewHandlingStrategy.restoreView(ViewHandlingStrategy.java:123)
    at com.sun.faces.application.view.FaceletViewHandlingStrategy.restoreView(FaceletViewHandlingStrategy.java:452)
    at com.sun.faces.application.view.MultiViewHandler.restoreView(MultiViewHandler.java:148)
    at javax.faces.application.ViewHandlerWrapper.restoreView(ViewHandlerWrapper.java:303)
    at com.sun.faces.lifecycle.RestoreViewPhase.execute(RestoreViewPhase.java:189)
    at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101)
    at com.sun.faces.lifecycle.RestoreViewPhase.doPhase(RestoreViewPhase.java:113)
    at com.sun.faces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:118)
    at javax.faces.webapp.FacesServlet.service(FacesServlet.java:409)
    // Remnant omitted for brevity.

因此，在状态管理需要访问整个组件树的恢复视图阶段期间会发生这种情况。 UIRepeat反过来需要在访问其子项时设置行索引。

根据UIRepeat#doVisitChildren()来源，行索引设置为-1。最终目标是只访问树中的子节点，而不是迭代模型值，也不渲染任何东西。它只需要DataModel以便能够设置行索引。 datamodel的值是您看到要调用的getter的列表。如果一切正常，则在恢复视图阶段只应调用此getter一次。但是，如果在例如渲染响应阶段期间调用它，那么您可能会担心这一点，因为它完全没必要。

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