Myfaces 2.2、Spring webflow 2.4.6 的 NullPointerException

【问题标题】：NullPointerException with Myfaces 2.2, Spring webflow 2.4.6Myfaces 2.2、Spring webflow 2.4.6 的 NullPointerException
【发布时间】：2017-09-27 17:11:10
【问题描述】：

我在 WebSphere 应用服务器上运行 PrimeFaces 5.3 和 Spring 4.3.11。我们正在迁移到使用 Apache MyFaces 2.2 作为 JSF 实现的新版本的 WebSphere。

迁移后，我在使用 Spring Web Flow 的网页上收到 NullPointerException。请查看下面的堆栈跟踪。

在 Stack Overflow 上有一个关于类似问题的讨论。它建议将 JVM 参数 org.apache.el.parser.COERCE_TO_ZERO 设置为 true。但是设置此参数会在其他网页上产生不同的功能问题。

欢迎提出任何建议。

非常感谢。

<<< stack trace >>>>

[9/26/17 17:36:21:141 EDT] 000001b4 PrimeExceptio E   <Null Message>
                                 java.lang.NullPointerException
    at org.apache.myfaces.view.facelets.tag.TagAttributeImpl.getBoolean(TagAttributeImpl.java:143)
    at org.apache.myfaces.view.facelets.tag.jstl.core.IfHandler.apply(IfHandler.java:110)
    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:375)
    at javax.faces.view.facelets.DelegatingMetaTagHandler.apply(DelegatingMetaTagHandler.java:50)
    at org.apache.myfaces.view.facelets.tag.ui.CompositionHandler.apply(CompositionHandler.java:161)
    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.include(DefaultFacelet.java:526)
    at org.apache.myfaces.view.facelets.impl.DefaultFacelet.include(DefaultFacelet.java:580)
    at org.apache.myfaces.view.facelets.impl.DefaultFacelet.include(DefaultFacelet.java:558)
    at org.apache.myfaces.view.facelets.impl.DefaultFaceletContext.includeFacelet(DefaultFaceletContext.java:240)
    at org.apache.myfaces.view.facelets.tag.ui.IncludeHandler.apply(IncludeHandler.java:228)
    at javax.faces.view.facelets.DelegatingMetaTagHandler.applyNextHandler(DelegatingMetaTagHandler.java:55)
    at org.apache.myfaces.view.facelets.tag.jsf.ComponentTagHandlerDelegate.apply(ComponentTagHandlerDelegate.java:375)
    at javax.faces.view.facelets.DelegatingMetaTagHandler.apply(DelegatingMetaTagHandler.java:50)
    at org.apache.myfaces.view.facelets.tag.composite.CompositeComponentResourceTagHandler.apply(CompositeComponentResourceTagHandler.java:725)
    at org.apache.myfaces.view.facelets.impl.DefaultFaceletContext$CompositeComponentTemplateManager.apply(DefaultFaceletContext.java:707)
    at org.apache.myfaces.view.facelets.impl.DefaultFaceletContext.includeCompositeComponentDefinition(DefaultFaceletContext.java:666)
    at org.apache.myfaces.view.facelets.tag.composite.InsertChildrenHandler.apply(InsertChildrenHandler.java:78)
    at javax.faces.view.facelets.CompositeFaceletHandler.apply(CompositeFaceletHandler.java:46)
    at org.apache.myfaces.view.facelets.tag.composite.ImplementationHandler.apply(ImplementationHandler.java:67)
    at javax.faces.view.facelets.CompositeFaceletHandler.apply(CompositeFaceletHandler.java:46)
    at org.apache.myfaces.view.facelets.tag.composite.CompositeComponentDefinitionTagHandler.apply(CompositeComponentDefinitionTagHandler.java:257)
    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.applyCompositeComponent(DefaultFacelet.java:614)
    at org.apache.myfaces.view.facelets.impl.DefaultFaceletContext.applyCompositeComponent(DefaultFaceletContext.java:795)
    at org.apache.myfaces.view.facelets.tag.composite.CompositeComponentResourceTagHandler.applyCompositeComponentFacelet(CompositeComponentResourceTagHandler.java:443)
    at org.apache.myfaces.view.facelets.tag.composite.CompositeComponentResourceTagHandler.applyNextHandler(CompositeComponentResourceTagHandler.java:216)
    at org.apache.myfaces.view.facelets.tag.jsf.ComponentTagHandlerDelegate.apply(ComponentTagHandlerDelegate.java:375)
    at javax.faces.view.facelets.DelegatingMetaTagHandler.apply(DelegatingMetaTagHandler.java:50)
    at org.apache.myfaces.view.facelets.tag.ui.CompositionHandler.apply(CompositionHandler.java:161)
    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.include(DefaultFacelet.java:526)
    at org.apache.myfaces.view.facelets.impl.DefaultFacelet.include(DefaultFacelet.java:580)
    at org.apache.myfaces.view.facelets.impl.DefaultFacelet.include(DefaultFacelet.java:558)
    at org.apache.myfaces.view.facelets.impl.DefaultFaceletContext.includeFacelet(DefaultFaceletContext.java:240)
    at org.apache.myfaces.view.facelets.tag.ui.IncludeHandler.apply(IncludeHandler.java:228)
    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:375)
    at javax.faces.view.facelets.DelegatingMetaTagHandler.apply(DelegatingMetaTagHandler.java:50)
    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:375)
    at javax.faces.view.facelets.DelegatingMetaTagHandler.apply(DelegatingMetaTagHandler.java:50)
    at org.apache.myfaces.view.facelets.tag.ui.DefineHandler.applyDefinition(DefineHandler.java:86)
    at org.apache.myfaces.view.facelets.tag.ui.CompositionHandler.apply(CompositionHandler.java:178)
    at org.apache.myfaces.view.facelets.impl.TemplateContextImpl$TemplateManagerImpl.apply(TemplateContextImpl.java:193)
    at org.apache.myfaces.view.facelets.impl.TemplateContextImpl.includeDefinition(TemplateContextImpl.java:136)
    at org.apache.myfaces.view.facelets.impl.DefaultFaceletContext.includeDefinition(DefaultFaceletContext.java:476)
    at org.apache.myfaces.view.facelets.tag.ui.InsertHandler.apply(InsertHandler.java:94)
    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:375)
    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 org.apache.myfaces.view.facelets.compiler.EncodingHandler.apply(EncodingHandler.java:48)
    at org.apache.myfaces.view.facelets.impl.DefaultFacelet.include(DefaultFacelet.java:526)
    at org.apache.myfaces.view.facelets.impl.DefaultFacelet.include(DefaultFacelet.java:580)
    at org.apache.myfaces.view.facelets.impl.DefaultFacelet.include(DefaultFacelet.java:558)
    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:194)
    at org.apache.myfaces.view.facelets.FaceletViewDeclarationLanguage.buildView(FaceletViewDeclarationLanguage.java:477)
    at org.apache.myfaces.lifecycle.RenderResponseExecutor.execute(RenderResponseExecutor.java:78)
    at org.apache.myfaces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:267)
    at org.springframework.faces.support.LifecycleWrapper.render(LifecycleWrapper.java:54)
    at org.springframework.faces.webflow.JsfView.render(JsfView.java:87)
    at org.springframework.webflow.engine.ViewState.render(ViewState.java:293)
    at org.springframework.webflow.engine.ViewState.refresh(ViewState.java:242)
    at org.springframework.webflow.engine.ViewState.resume(ViewState.java:220)
    at org.springframework.webflow.engine.Flow.resume(Flow.java:537)
    at org.springframework.webflow.engine.impl.FlowExecutionImpl.resume(FlowExecutionImpl.java:259)
    at org.springframework.webflow.executor.FlowExecutorImpl.resumeExecution(FlowExecutorImpl.java:169)
    at org.springframework.webflow.mvc.servlet.FlowHandlerAdapter.handle(FlowHandlerAdapter.java:253)
    at org.springframework.faces.webflow.JsfFlowHandlerAdapter.handle(JsfFlowHandlerAdapter.java:57)
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:967)
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:901)
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:970)
    at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:861)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:687)
    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:846)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:790)
    at com.ibm.ws.webcontainer.servlet.ServletWrapper.service(ServletWrapper.java:1235)
    at com.ibm.ws.webcontainer.servlet.ServletWrapper.handleRequest(ServletWrapper.java:779)
    at com.ibm.ws.webcontainer.servlet.ServletWrapper.handleRequest(ServletWrapper.java:478)
    at com.ibm.ws.webcontainer.servlet.ServletWrapperImpl.handleRequest(ServletWrapperImpl.java:178)
    at com.ibm.ws.webcontainer.filter.WebAppFilterChain.invokeTarget(WebAppFilterChain.java:143)
    at com.ibm.ws.webcontainer.filter.WebAppFilterChain.doFilter(WebAppFilterChain.java:96)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:317)
    at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:127)
    at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:91)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:331)
    at org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:114)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:331)
    at org.springframework.security.web.authentication.preauth.AbstractPreAuthenticatedProcessingFilter.doFilter(AbstractPreAuthenticatedProcessingFilter.java:121)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:331)
    at org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:105)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:331)
    at org.springframework.security.web.FilterChainProxy.doFilterInternal(FilterChainProxy.java:214)
    at org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:177)
    at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:346)
    at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:262)
    at com.ibm.ws.webcontainer.filter.FilterInstanceWrapper.doFilter(FilterInstanceWrapper.java:197)
    at com.ibm.ws.webcontainer.filter.WebAppFilterChain.doFilter(WebAppFilterChain.java:90)
    at com.ibm.ws.webcontainer.filter.WebAppFilterManager.doFilter(WebAppFilterManager.java:969)
    at com.ibm.ws.webcontainer.filter.WebAppFilterManager.invokeFilters(WebAppFilterManager.java:1109)
    at com.ibm.ws.webcontainer.servlet.CacheServletWrapper.handleRequest(CacheServletWrapper.java:82)
    at com.ibm.ws.webcontainer.WebContainer.handleRequest(WebContainer.java:963)
    at com.ibm.ws.webcontainer.WSWebContainer.handleRequest(WSWebContainer.java:1817)
    at com.ibm.ws.webcontainer.channel.WCChannelLink.ready(WCChannelLink.java:382)
    at com.ibm.ws.http.channel.inbound.impl.HttpInboundLink.handleDiscrimination(HttpInboundLink.java:465)
    at com.ibm.ws.http.channel.inbound.impl.HttpInboundLink.handleNewRequest(HttpInboundLink.java:532)
    at com.ibm.ws.http.channel.inbound.impl.HttpInboundLink.processRequest(HttpInboundLink.java:318)
    at com.ibm.ws.http.channel.inbound.impl.HttpICLReadCallback.complete(HttpICLReadCallback.java:88)
    at com.ibm.ws.tcp.channel.impl.AioReadCompletionListener.futureCompleted(AioReadCompletionListener.java:175)
    at com.ibm.io.async.AbstractAsyncFuture.invokeCallback(AbstractAsyncFuture.java:217)
    at com.ibm.io.async.AsyncChannelFuture.fireCompletionActions(AsyncChannelFuture.java:161)
    at com.ibm.io.async.AsyncFuture.completed(AsyncFuture.java:138)
    at com.ibm.io.async.ResultHandler.complete(ResultHandler.java:204)
    at com.ibm.io.async.ResultHandler.runEventProcessingLoop(ResultHandler.java:775)
    at com.ibm.io.async.ResultHandler$2.run(ResultHandler.java:905)
    at com.ibm.ws.util.ThreadPool$Worker.run(ThreadPool.java:1909)

【问题讨论】：

  • 你能提供你提到的堆栈溢出问题的链接吗？
  • 无需在标题中添加所有“标签”。而是添加与强制问题相关的内容。而且堆栈跟踪中没有任何与 PrimeFaces 相关的内容。
  • 这里是其他堆栈溢出问题的链接stackoverflow.com/questions/19690794/…

标签： jsf nullpointerexception spring-webflow


【解决方案1】：

我能够通过创建扩展默认 ELResolver 的新类来解决此问题。

这里提到了这种方法http://balusc.omnifaces.org/2015/10/the-empty-string-madness.html?m=1

public class EmptyToNullStringELResolver extends ELResolver {

@Override
public Class<?> getCommonPropertyType(ELContext context, Object base) {
    return String.class;
}

@Override
public Object convertToType(ELContext context, Object value, Class<?> 
          targetType) {
    if (value == null && targetType == String.class) {
        context.setPropertyResolved(true);
    }

    if (value == null && targetType == Boolean.class) {
        context.setPropertyResolved(true);
        return false;
    }
    return value;
}

【讨论】：

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