org.omnifaces.facesviews.FacesViewsForwardingFilter的NullPointerException

Question

我在WildFly 8.2上运行Java 7应用程序。我使用OmniFaces 1.8.1。我在日志文件中看到了与NullPointerExceptions相关的FacesViewsForwardingFilter

2015-02-11 15:42:22,870 ERROR [io.undertow.request] (default task-12) UT005023: Exception handling request to /login: java.lang.NullPointerException
        at org.omnifaces.facesviews.FacesViewsForwardingFilter.doFilter(FacesViewsForwardingFilter.java:122) [omnifaces-1.8.1.jar:1.8.1-20140603]
        at org.omnifaces.filter.HttpFilter.doFilter(HttpFilter.java:77) [omnifaces-1.8.1.jar:1.8.1-20140603]
        at io.undertow.servlet.core.ManagedFilter.doFilter(ManagedFilter.java:60) [undertow-servlet-1.1.0.Final.jar:1.1.0.Final]
        at io.undertow.servlet.handlers.FilterHandler$FilterChainImpl.doFilter(FilterHandler.java:132) [undertow-servlet-1.1.0.Final.jar:1.1.0.Final]

2015-02-11 15:42:31,524 ERROR [io.undertow.request] (default task-15) UT005023: Exception handling request to /search.xhtml: java.lang.NullPointerException
        at org.omnifaces.facesviews.FacesViewsForwardingFilter.doFilter(FacesViewsForwardingFilter.java:153) [omnifaces-1.8.1.jar:1.8.1-20140603]
        at org.omnifaces.filter.HttpFilter.doFilter(HttpFilter.java:77) [omnifaces-1.8.1.jar:1.8.1-20140603]
        at io.undertow.servlet.core.ManagedFilter.doFilter(ManagedFilter.java:60) [undertow-servlet-1.1.0.Final.jar:1.1.0.Final]

在服务器启动期间，我看到了以下内容：

2015-02-11 12:28:35,667 ERROR [io.undertow.request] (default task-3) UT005023: Exception handling request to /terms/index: java.lang.IllegalStateException: Illegal attempt to set ViewHandler after a response has been rendered.
        at com.sun.faces.application.ApplicationImpl.setViewHandler(ApplicationImpl.java:583) [jsf-impl-2.2.8-jbossorg-1.jar:]
        at javax.faces.application.ApplicationWrapper.setViewHandler(ApplicationWrapper.java:288) [jboss-jsf-api_2.2_spec-2.2.8.jar:2.2.8]
        at org.jboss.as.jsf.injection.weld.ForwardingApplication.setViewHandler(ForwardingApplication.java:367) [wildfly-jsf-injection-8.2.0.Final.jar:8.2.0.Final]
        at org.omnifaces.facesviews.FacesViewsForwardingFilter.init(FacesViewsForwardingFilter.java:95) [omnifaces-1.8.1.jar:1.8.1-20140603]
        at io.undertow.servlet.core.LifecyleInterceptorInvocation.proceed(LifecyleInterceptorInvocation.java:111) [undertow-servlet-1.1.0.Final.jar:1.1.0.Final]
        at org.wildfly.extension.undertow.security.RunAsLifecycleInterceptor.init(RunAsLifecycleInterceptor.java:85)

web.xml中的相关配置是：

<servlet>
    <servlet-name>facesServlet</servlet-name>
    <servlet-class>javax.faces.webapp.FacesServlet</servlet-class>
    <load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
    <servlet-name>facesServlet</servlet-name>
    <url-pattern>*.html</url-pattern>
    <url-pattern>*.xhtml</url-pattern>
    <url-pattern>/javax.faces.resource/*</url-pattern>
</servlet-mapping>
<context-param>
    <param-name>org.omnifaces.FACES_VIEWS_SCAN_PATHS</param-name>
    <param-value>/*.xhtml</param-value>
</context-param>

这是如何造成的，我如何解决呢？

Answer 1

这些NPEs表明过滤器的初始化失败了。您应该能够在日志中的早期，在服务器启动期间找到线索。

2015-02-11 12:28:35,667错误io.undertow.request UT005023:对/terms/索引的异常处理请求: java.lang.IllegalStateException:在发出响应后非法尝试设置ViewHandler。

IllegalStateException是一个有用的提示。FacesViewsViewHandler是在OmniFaces 1.x中通过FacesViewsForwardingFilter延迟初始化的，该FacesViewsForwardingFilter在OmniFaces匹配的/*.xhtml上进行了第一次请求。但是，如果在筛选器之前调用FacesServlet，则该异常将失败。您有一个可疑的*.html映射，它将触发FacesServlet而不触发过滤器。您有一个简单的HTML页面作为欢迎文件吗？为什么不把它重命名为*.xhtml呢？

在任何情况下，初始化排序错误都是固定 2.0中的OmniFaces。因此，升级应该可以。