尝试运行 Apache MyFaces 2.0.2 应用程序时出现未知 NullPointerException答案

【问题标题】：Unknown NullPointerException when trying to run Apache MyFaces 2.0.2 application尝试运行 Apache MyFaces 2.0.2 应用程序时出现未知 NullPointerException
【发布时间】：2012-09-15 07:02:37
【问题描述】：

我正在尝试运行基于Apache MyFaces 2.0.2 和Apache Trinindad 2.0.1 构建的示例JSF 2.0 应用程序。我在weblogic 11g 上运行。我在无法调试的特立尼达内部类中遇到NullPointerException。这是一个例外

javax.faces.FacesException: java.lang.NullPointerException
    at org.apache.myfaces.shared_impl.context.ExceptionHandlerImpl.wrap(ExceptionHandlerImpl.java:241)
    at org.apache.myfaces.shared_impl.context.ExceptionHandlerImpl.handle(ExceptionHandlerImpl.java:156)
    at org.apache.myfaces.lifecycle.LifecycleImpl.executePhase(LifecycleImpl.java:191)
    at org.apache.myfaces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:118)
    at javax.faces.webapp.FacesServlet.service(FacesServlet.java:189)
    at weblogic.servlet.internal.StubSecurityHelper$ServletServiceAction.run(StubSecurityHelper.java:227)
    at weblogic.servlet.internal.StubSecurityHelper.invokeServlet(StubSecurityHelper.java:125)
    at weblogic.servlet.internal.ServletStubImpl.execute(ServletStubImpl.java:300)
    at weblogic.servlet.internal.TailFilter.doFilter(TailFilter.java:26)
    at weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:56)
    at com.others.CacheFilter.doFilter(CacheFilter.java:56)
    at weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:56)
    at weblogic.servlet.internal.RequestEventsFilter.doFilter(RequestEventsFilter.java:27)
    at weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:56)
    at weblogic.servlet.internal.WebAppServletContext$ServletInvocationAction.wrapRun(WebAppServletContext.java:3715)
    at weblogic.servlet.internal.WebAppServletContext$ServletInvocationAction.run(WebAppServletContext.java:3681)
    at weblogic.security.acl.internal.AuthenticatedSubject.doAs(AuthenticatedSubject.java:321)
    at weblogic.security.service.SecurityManager.runAs(SecurityManager.java:120)
    at weblogic.servlet.internal.WebAppServletContext.securedExecute(WebAppServletContext.java:2277)
    at weblogic.servlet.internal.WebAppServletContext.execute(WebAppServletContext.java:2183)
    at weblogic.servlet.internal.ServletRequestImpl.run(ServletRequestImpl.java:1454)
    at weblogic.work.ExecuteThread.execute(ExecuteThread.java:207)
    at weblogic.work.ExecuteThread.run(ExecuteThread.java:176)
Caused by: java.lang.NullPointerException
    at java.util.concurrent.ConcurrentHashMap.get(ConcurrentHashMap.java:768)
    at org.apache.myfaces.trinidadinternal.application.ViewDeclarationLanguageFactoryImpl._getInternalView(ViewDeclarationLanguageFactoryImpl.java:104)
    at org.apache.myfaces.trinidadinternal.application.ViewDeclarationLanguageFactoryImpl.getViewDeclarationLanguage(ViewDeclarationLanguageFactoryImpl.java:79)
    at org.apache.myfaces.application.ViewHandlerImpl.getViewDeclarationLanguage(ViewHandlerImpl.java:157)
    at javax.faces.application.ViewHandlerWrapper.getViewDeclarationLanguage(ViewHandlerWrapper.java:128)
    at org.apache.myfaces.lifecycle.RestoreViewExecutor.execute(RestoreViewExecutor.java:150)
    at org.apache.myfaces.lifecycle.LifecycleImpl.executePhase(LifecycleImpl.java:171)
    ... 20 more

在生命周期RESTOREVIEW PHASE 之后遇到此错误。这是我的web.xml。

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5">
  <display-name>/*appname*/</display-name>
  <context-param>
    <param-name>javax.faces.PROJECT_STAGE</param-name>
    <param-value>Development</param-value>
  </context-param>
  <context-param>
    <description>State saving method: 'client' or 'server' (=default). See JSF Specification 2.5.2</description>
    <param-name>javax.faces.STATE_SAVING_METHOD</param-name>
    <param-value>client</param-value>
  </context-param>
  <context-param>
    <param-name>org.apache.myfaces.ALLOW_JAVASCRIPT</param-name>
    <param-value>true</param-value>
  </context-param>
  <context-param>
    <param-name>org.apache.myfaces.PRETTY_HTML</param-name>
    <param-value>true</param-value>
  </context-param>
  <context-param>
    <param-name>org.apache.myfaces.DETECT_JAVASCRIPT</param-name>
    <param-value>false</param-value>
  </context-param>
  <context-param>
    <param-name>org.apache.myfaces.AUTO_SCROLL</param-name>
    <param-value>true</param-value>
  </context-param>
 <context-param>
  <param-name>facelets.SKIP_COMMENTS</param-name> 
  <param-value>true</param-value> 
 </context-param>
 <context-param>
    <param-name>javax.faces.DEFAULT_SUFFIX</param-name>
    <param-value>.xhtml</param-value>
  </context-param>
    <context-param>
    <param-name>javax.faces.FACELETS_VIEW_MAPPINGS</param-name>
    <param-value>.xhtml</param-value>
  </context-param>
  <context-param>
    <param-name>org.apache.myfaces.ERROR_HANDLING</param-name>
    <param-value>false</param-value>
  </context-param>
  <context-param>
     <param-name>javax.faces.PARTIAL_STATE_SAVING_METHOD</param-name>
     <param-value>false</param-value>
  </context-param>
 <servlet>
    <servlet-name>Faces Servlet</servlet-name>
    <servlet-class>javax.faces.webapp.FacesServlet</servlet-class>
    <load-on-startup>1</load-on-startup>
  </servlet>
  <servlet-mapping>
    <servlet-name>Faces Servlet</servlet-name>
    <url-pattern>*.xhtml</url-pattern>
  </servlet-mapping>

  <servlet>
    <servlet-name>resources</servlet-name>
    <servlet-class>org.apache.myfaces.trinidad.webapp.ResourceServlet</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>resources</servlet-name>
    <url-pattern>/adf/*</url-pattern>
  </servlet-mapping>

  <filter>
    <filter-name>trinidad</filter-name>
    <filter-class>org.apache.myfaces.trinidad.webapp.TrinidadFilter</filter-class>
  </filter>
  <filter-mapping>
    <filter-name>trinidad</filter-name>
    <servlet-name>faces</servlet-name>
  </filter-mapping>
    <error-page>
    <exception-type>java.lang.Exception</exception-type>
    <location>/others/Error.xhtml</location>
</error-page>
    <error-page>
    <exception-type>java.lang.NullPointerException</exception-type>
    <location>/others/Error.xhtml</location>
</error-page>
</web-app>

这是我的faces-config.xml

<?xml version="1.0" encoding="UTF-8"?>

<faces-config
    xmlns="http://java.sun.com/xml/ns/javaee"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-facesconfig_2_0.xsd"
    version="2.0">

<application>
    <locale-config>
        <default-locale>en</default-locale>
        <supported-locale>en</supported-locale>
    </locale-config>
    <resource-bundle>
            <base-name>messages</base-name>
            <var>msgs</var>
        </resource-bundle>
    <default-render-kit-id>
        org.apache.myfaces.trinidad.core
    </default-render-kit-id>  
  </application>

    <lifecycle>
        <phase-listener>com.others.LifeCycleListener</phase-listener>
    </lifecycle>

</faces-config>

这是我正在尝试访问的Home.xhtml

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml"
    xmlns:ui="http://java.sun.com/jsf/facelets"
    xmlns:h="http://java.sun.com/jsf/html"
    xmlns:f="http://java.sun.com/jsf/core"
    xmlns:tr="http://myfaces.apache.org/trinidad"
    xmlns:trh="http://myfaces.apache.org/trinidad/html">

<h:body>
<ui:composition template="../Templates/homelayout.xhtml">

    <ui:define name="pagetitle">Home</ui:define>


    <ui:define name="bodycontent">
        <h:outputText value="This is an output text"/>
        <h:outputText value="This is an output text"/>
        <h:outputText value="This is an output text"/>
        <h:outputText value="This is an output text"/>
        <h:outputText value="This is an output text"/>
    </ui:define>

</ui:composition>

</h:body>

这是我的文件夹结构快照

有人可以解释一下 Nullpointer 异常的原因吗？还有怎么解决的？

提前致谢。

更新：我删除了旧的 MyFaces 2.0.2 罐子并添加了 MyFaces 2.0.14 罐子。我还在web.xml 中添加了一个错误页面以获取完整的错误信息。这是它现在抛出的异常消息。

java.lang.NullPointerException
    at java.util.concurrent.ConcurrentHashMap.get(ConcurrentHashMap.java:768)
    at org.apache.myfaces.trinidadinternal.application.ViewDeclarationLanguageFactoryImpl._getInternalView(ViewDeclarationLanguageFactoryImpl.java:104)
    at org.apache.myfaces.trinidadinternal.application.ViewDeclarationLanguageFactoryImpl.getViewDeclarationLanguage(ViewDeclarationLanguageFactoryImpl.java:79)
    at org.apache.myfaces.application.ViewHandlerImpl.getViewDeclarationLanguage(ViewHandlerImpl.java:158)
    at javax.faces.application.ViewHandlerWrapper.getViewDeclarationLanguage(ViewHandlerWrapper.java:128)
    at org.apache.myfaces.lifecycle.RestoreViewExecutor.execute(RestoreViewExecutor.java:151)
    at org.apache.myfaces.lifecycle.LifecycleImpl.executePhase(LifecycleImpl.java:171)
    at org.apache.myfaces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:118)
    at javax.faces.webapp.FacesServlet.service(FacesServlet.java:189)
    at weblogic.servlet.internal.StubSecurityHelper$ServletServiceAction.run(StubSecurityHelper.java:227)
    at weblogic.servlet.internal.StubSecurityHelper.invokeServlet(StubSecurityHelper.java:125)
    at weblogic.servlet.internal.ServletStubImpl.execute(ServletStubImpl.java:300)
    at weblogic.servlet.internal.TailFilter.doFilter(TailFilter.java:26)
    at weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:56)
    at com.others.CacheFilter.doFilter(CacheFilter.java:56)
    at weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:56)
    at weblogic.servlet.internal.RequestEventsFilter.doFilter(RequestEventsFilter.java:27)
    at weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:56)
    at weblogic.servlet.internal.WebAppServletContext$ServletInvocationAction.wrapRun(WebAppServletContext.java:3715)
    at weblogic.servlet.internal.WebAppServletContext$ServletInvocationAction.run(WebAppServletContext.java:3681)
    at weblogic.security.acl.internal.AuthenticatedSubject.doAs(AuthenticatedSubject.java:321)
    at weblogic.security.service.SecurityManager.runAs(SecurityManager.java:120)
    at weblogic.servlet.internal.WebAppServletContext.securedExecute(WebAppServletContext.java:2277)
    at weblogic.servlet.internal.WebAppServletContext.execute(WebAppServletContext.java:2183)
    at weblogic.servlet.internal.ServletRequestImpl.run(ServletRequestImpl.java:1454)
    at weblogic.work.ExecuteThread.execute(ExecuteThread.java:207)
    at weblogic.work.ExecuteThread.run(ExecuteThread.java:176)

【问题讨论】：

MyFaces 2.0.2 是一个非常旧的版本。请尝试更新版本。
您可以尝试使用 Trinidad 的 Maven 原型 myfaces.apache.org/build-tools/archetypes/… 设置您的项目
@lu4242 - 我添加了新版本的 MyFaces jar，还添加了一个错误页面来获取实际的错误信息。相应地更新了问题。请帮助。
Stracktrace 建议 viewId 是 null。
您的 Trinidad 过滤器已映射到一个不存在的 servlet 名称。您将它映射到<servlet-name>faces</servlet-name>，但您实际的JSF servlet 的名称为<servlet-name>Faces Servlet</servlet-name>。也许这就是根本原因？（我无法从理论或经验中证实这一点，因为我从未使用过特立尼达，而且例外情况非常糟糕）。相应地修复过滤器映射并重试。

标签： jsf jsf-2 myfaces trinidad

【解决方案1】：

终于解决了。

感谢 BalusC 指出 web.xml 中的类型错误。

解决方案：

在将faces servlet 映射更改为.xhtml 后，我试图通过以下方式访问我的应用程序。

http://hostname/contextname/faces/others/Home.xhtml

现在我刚刚从网址中删除了faces 并开始像这样访问我的应用程序

http://hostname/contextname/others/Home.xhtml

令我惊讶的是，它没有给出任何异常并显示了我的主页。

【讨论】：