我在大型Web应用程序中一起使用OmniFaces 1.10和Apache MyFaces 2.2.6。当应用程序在生产中运行时，我在Web服务器（Tomcat）日志中得到以下形式的虚假异常：
java.lang.NullPointerException
at org.apache.myfaces.el.unified.resolver.ManagedBeanResolver$5.put(ManagedBeanResolver.java:101)
at org.apache.myfaces.el.unified.resolver.ManagedBeanResolver.putInScope(ManagedBeanResolver.java:367)
at org.apache.myfaces.el.unified.resolver.ManagedBeanResolver.createManagedBean(ManagedBeanResolver.java:340)
at org.apache.myfaces.el.unified.resolver.ManagedBeanResolver.getValue(ManagedBeanResolver.java:296)
at javax.el.CompositeELResolver.getValue(CompositeELResolver.java:67)
at org.apache.myfaces.el.unified.resolver.FacesCompositeELResolver.getValue(FacesCompositeELResolver.java:179)
at org.apache.el.parser.AstIdentifier.getValue(AstIdentifier.java:72)
at org.apache.el.parser.AstValue.getValue(AstValue.java:147)
at org.apache.el.ValueExpressionImpl.getValue(ValueExpressionImpl.java:189)
at org.apache.myfaces.view.facelets.el.ContextAwareTagValueExpression.getValue(ContextAwareTagValueExpression.java:96)
at org.apache.myfaces.view.facelets.tag.TagAttributeImpl.getObject(TagAttributeImpl.java:431)
at org.apache.myfaces.view.facelets.tag.TagAttributeImpl.getBoolean(TagAttributeImpl.java:143)
at org.apache.myfaces.view.facelets.tag.jstl.core.ChooseWhenHandler.isTestTrue(ChooseWhenHandler.java:68)
at org.apache.myfaces.view.facelets.tag.jstl.core.ChooseHandler.apply(ChooseHandler.java:182)
at javax.faces.view.facelets.CompositeFaceletHandler.apply(CompositeFaceletHandler.java:46)
at javax.faces.view.facelets.DelegatingMetaTagHandler.applyNextHandler(DelegatingMetaTagHandler.java:55)
at org.apache.myfaces.view.facelets.tag.jsf.ComponentTagHandlerDelegate.apply(ComponentTagHandlerDelegate.java:373)
at javax.faces.view.facelets.DelegatingMetaTagHandler.apply(DelegatingMetaTagHandler.java:50)
at javax.faces.view.facelets.CompositeFaceletHandler.apply(CompositeFaceletHandler.java:46)
at org.apache.myfaces.view.facelets.tag.jsf.core.ViewHandler.apply(ViewHandler.java:195)
at javax.faces.view.facelets.CompositeFaceletHandler.apply(CompositeFaceletHandler.java:46)
at org.apache.myfaces.view.facelets.compiler.NamespaceHandler.apply(NamespaceHandler.java:59)
at javax.faces.view.facelets.CompositeFaceletHandler.apply(CompositeFaceletHandler.java:46)
at javax.faces.view.facelets.CompositeFaceletHandler.apply(CompositeFaceletHandler.java:46)
at org.apache.myfaces.view.facelets.compiler.EncodingHandler.apply(EncodingHandler.java:48)
at org.apache.myfaces.view.facelets.impl.DefaultFacelet.include(DefaultFacelet.java:520)
at org.apache.myfaces.view.facelets.impl.DefaultFacelet.include(DefaultFacelet.java:574)
at org.apache.myfaces.view.facelets.impl.DefaultFacelet.include(DefaultFacelet.java:552)
at org.apache.myfaces.view.facelets.impl.DefaultFaceletContext.includeFacelet(DefaultFaceletContext.java:240)
at org.apache.myfaces.view.facelets.tag.ui.CompositionHandler.apply(CompositionHandler.java:151)
at org.apache.myfaces.view.facelets.compiler.NamespaceHandler.apply(NamespaceHandler.java:59)
at org.apache.myfaces.view.facelets.compiler.EncodingHandler.apply(EncodingHandler.java:48)
at org.apache.myfaces.view.facelets.impl.DefaultFacelet.apply(DefaultFacelet.java:188)
at org.apache.myfaces.view.facelets.FaceletViewDeclarationLanguage.buildView(FaceletViewDeclarationLanguage.java:477)
at org.omnifaces.viewhandler.RestorableViewHandler.restoreView(RestorableViewHandler.java:80)
at org.apache.myfaces.lifecycle.RestoreViewExecutor.execute(RestoreViewExecutor.java:170)
at org.apache.myfaces.lifecycle.LifecycleImpl.executePhase(LifecycleImpl.java:196)
at org.apache.myfaces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:143)
at javax.faces.webapp.FacesServlet.service(FacesServlet.java:198)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.primefaces.webapp.filter.FileUploadFilter.doFilter(FileUploadFilter.java:72)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
我确信这是一个问题，或者至少是应用程序中的边缘情况（例如.xhtml文件错误地使用了一些bean变量）但我无法在测试用例中重现它，并且以前版本的MyFaces也不会发生这种情况和OmniFaces。
异常本身似乎是因为OmniFaces＆＃34; RestorableViewHandler＆＃34;尝试恢复视图只是为了查看它是否包含应该自动恢复的标记。当恢复的视图不包含标记时，它会抛弃（已经）恢复的视图。除了明显的性能问题，这也会触发这个NullPointerException，所以我不想要这个，因此我正在寻找一种方法来完成禁用RestorableViewHandler。我知道当我这样做时，我将无法使用标签＆＃34; enableRestorableView＆＃34;，但这没关系。
答案 0 :(得分：3)
如果不在OmniFaces源中进行黑客攻击，则无法禁用它。根据{{3}}，已经通过让<o:enableRestorableView>设置应用程序范围的属性（一旦在某处使用）来修复此问题，以便RestorableViewHandler可以决定是否尝试恢复视图。
请注意，我真的更喜欢动态注册RestorableViewHandler，但是当应用程序之前已处理过请求时，无法动态注册ViewHandler。 issue 92
此解决方案在今天的It would only cause an IllegalStateException（和1.11 snapshot，适用于2.x用户）中提供。