java.lang.NullPointerException在org.springframework.faces.webflow.FlowViewStateManager.saveView

Question

我在Tomcat 7.0.22中使用JSF 2.1，Spring 3.0.5，Spring Web Flow 2.3.0開始了一個項目。 當我把SWF JAR文件（綁定，臉，JS，js.resources和一個Webflow）在類路徑中，我不能導航到任何網頁，我得到這個：

SEVERE: Error Rendering View[/login.xhtml] 
java.lang.NullPointerException 
    at org.springframework.faces.webflow.FlowViewStateManager.saveView(FlowViewStateManager.java:181) 
    at com.sun.faces.application.view.WriteBehindStateWriter.flushToWriter(WriteBehindStateWriter.java:225) 
    at com.sun.faces.application.view.FaceletViewHandlingStrategy.renderView(FaceletViewHandlingStrategy.java:418) 
    at com.sun.faces.application.view.MultiViewHandler.renderView(MultiViewHandler.java:131) 
    at org.springframework.faces.webflow.FlowViewHandler.renderView(FlowViewHandler.java:99) 
    at javax.faces.application.ViewHandlerWrapper.renderView(ViewHandlerWrapper.java:288) 
    at org.springframework.faces.webflow.FlowViewHandler.renderView(FlowViewHandler.java:99) 
    at com.sun.faces.lifecycle.RenderResponsePhase.execute(RenderResponsePhase.java:121) 
    at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101) 
    at com.sun.faces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:139) 
    at javax.faces.webapp.FacesServlet.service(FacesServlet.java:594) 
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:304) .... 

當我刪除這些JAR文件，那麼所有頁面將被正確渲染。這是如何造成的，我該如何解決這個問題？

Answer 1

這是SWF中的一個錯誤。另見SWF issue 1461。它已在SWF 2.3.1中得到修復。所以，升級到SWF 2.3.1應該可以解決這個問題。