JSF自定义EL函数仅在第一次加载页面时起作用

我创建了一个（基于JSP的）自定义EL函数，用于呈现的标记中。函数将返回一个布尔值，以决定是否需要在页面上呈现页面组件。 我使用将其导入jsp页面

在第一次加载jsp页面时，一切都很完美。单击按钮后，表单将提交，然后我会收到类似“未找到的类加载器：实现EL函数的类”和“未找到函数”的错误。这是怎么回事？什么是修复

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实现该函数的类（com.util.WebContextLoader）作为实用程序类包含在war中

下面是堆栈跟踪

09:22:31,112 ERROR [STDERR] java.lang.ClassNotFoundException: No ClassLoaders found for: com.util.WebContextLoader
09:22:31,112 ERROR [STDERR]     at org.jboss.mx.loading.LoadMgr3.beginLoadTask(LoadMgr3.java:212)
09:22:31,112 ERROR [STDERR]     at org.jboss.mx.loading.RepositoryClassLoader.loadClassImpl(RepositoryClassLoader.java:521)
09:22:31,112 ERROR [STDERR]     at org.jboss.mx.loading.RepositoryClassLoader.loadClass(RepositoryClassLoader.java:415)
09:22:31,112 ERROR [STDERR]     at java.lang.ClassLoader.loadClass(ClassLoader.java:248)
09:22:31,112 ERROR [STDERR]     at java.lang.Class.forName0(Native Method)
09:22:31,112 ERROR [STDERR]     at java.lang.Class.forName(Class.java:169)
09:22:31,112 ERROR [STDERR]     at org.apache.el.lang.FunctionMapperImpl$Function.getMethod(FunctionMapperImpl.java:147)
09:22:31,112 ERROR [STDERR]     at org.apache.el.lang.FunctionMapperImpl.resolveFunction(FunctionMapperImpl.java:53)
09:22:31,112 ERROR [STDERR]     at org.apache.el.parser.AstFunction.getValue(AstFunction.java:71)
09:22:31,112 ERROR [STDERR]     at org.apache.el.ValueExpressionImpl.getValue(ValueExpressionImpl.java:186)
09:22:31,112 ERROR [STDERR]     at org.apache.jasper.el.JspValueExpression.getValue(JspValueExpression.java:101)
09:22:31,112 ERROR [STDERR]     at javax.faces.component.UIComponentBase.isRendered(UIComponentBase.java:390)
09:22:31,112 ERROR [STDERR]     at javax.faces.component.UIComponentBase.processDecodes(UIComponentBase.java:1018)
09:22:31,112 ERROR [STDERR]     at javax.faces.component.UIForm.processDecodes(UIForm.java:209)
09:22:31,112 ERROR [STDERR]     at javax.faces.component.UIComponentBase.processDecodes(UIComponentBase.java:1026)
09:22:31,112 ERROR [STDERR]     at javax.faces.component.UIViewRoot.processDecodes(UIViewRoot.java:540)
09:22:31,112 ERROR [STDERR]     at com.sun.faces.lifecycle.ApplyRequestValuesPhase.execute(ApplyRequestValuesPhase.java:78)
09:22:31,112 ERROR [STDERR]     at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:100)
09:22:31,112 ERROR [STDERR]     at com.sun.faces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:118)
09:22:31,112 ERROR [STDERR]     at javax.faces.webapp.FacesServlet.service(FacesServlet.java:265)
09:22:31,112 ERROR [STDERR]     at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
09:22:31,112 ERROR [STDERR]     at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
09:22:31,112 ERROR [STDERR]     at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
09:22:31,112 ERROR [STDERR]     at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
09:22:31,112 ERROR [STDERR]     at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
09:22:31,112 ERROR [STDERR]     at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
09:22:31,112 ERROR [STDERR]     at org.jboss.web.tomcat.filters.ReplyHeaderFilter.doFilter(ReplyHeaderFilter.java:96)
09:22:31,112 ERROR [STDERR]     at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
09:22:31,112 ERROR [STDERR]     at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
09:22:31,112 ERROR [STDERR]     at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:230)
09:22:31,112 ERROR [STDERR]     at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175)
09:22:31,112 ERROR [STDERR]     at org.jboss.web.tomcat.security.SecurityAssociationValve.invoke(SecurityAssociationValve.java:182)
09:22:31,112 ERROR [STDERR]     at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:432)
09:22:31,112 ERROR [STDERR]     at org.jboss.web.tomcat.security.JaccContextValve.invoke(JaccContextValve.java:84)
09:22:31,112 ERROR [STDERR]     at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
09:22:31,112 ERROR [STDERR]     at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
09:22:31,112 ERROR [STDERR]     at org.jboss.web.tomcat.service.jca.CachedConnectionValve.invoke(CachedConnectionValve.java:157)
09:22:31,112 ERROR [STDERR]     at org.apache.catalina.authenticator.SingleSignOn.invoke(SingleSignOn.java:420)
09:22:31,112 ERROR [STDERR]     at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
09:22:31,112 ERROR [STDERR]     at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:262)
09:22:31,112 ERROR [STDERR]     at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:844)
09:22:31,112 ERROR [STDERR]     at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:583)
09:22:31,112 ERROR [STDERR]     at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:446)
09:22:31,112 ERROR [STDERR]     at java.lang.Thread.run(Thread.java:619)


09:22:31,112 WARN  [lifecycle] org.apache.jasper.el.JspELException: /register.jsp(45,2) '#{g:displayPageComponent('registrationPage', 'regUnit')}' Function 'g:displayPageComponent' not found
javax.faces.FacesException: org.apache.jasper.el.JspELException: /register.jsp(45,2) '#{g:displayPageComponent('registrationPage', 'regUnit')}' Function 'g:displayPageComponent' not found
    at javax.faces.component.UIComponentBase.isRendered(UIComponentBase.java:393)
    at javax.faces.component.UIComponentBase.processDecodes(UIComponentBase.java:1018)
    at javax.faces.component.UIForm.processDecodes(UIForm.java:209)
    at javax.faces.component.UIComponentBase.processDecodes(UIComponentBase.java:1026)
    at javax.faces.component.UIViewRoot.processDecodes(UIViewRoot.java:540)
    at com.sun.faces.lifecycle.ApplyRequestValuesPhase.execute(ApplyRequestValuesPhase.java:78)
    at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:100)
    at com.sun.faces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:118)
    at javax.faces.webapp.FacesServlet.service(FacesServlet.java:265)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at org.jboss.web.tomcat.filters.ReplyHeaderFilter.doFilter(ReplyHeaderFilter.java:96)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:230)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175)
    at org.jboss.web.tomcat.security.SecurityAssociationValve.invoke(SecurityAssociationValve.java:182)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:432)
    at org.jboss.web.tomcat.security.JaccContextValve.invoke(JaccContextValve.java:84)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
    at org.jboss.web.tomcat.service.jca.CachedConnectionValve.invoke(CachedConnectionValve.java:157)
    at org.apache.catalina.authenticator.SingleSignOn.invoke(SingleSignOn.java:420)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:262)
    at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:844)
    at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:583)
    at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:446)
    at java.lang.Thread.run(Thread.java:619)
Caused by: org.apache.jasper.el.JspELException: /register.jsp(45,2) '#{g:displayPageComponent('registrationPage', 'regUnit')}' Function 'g:displayPageComponent' not found
    at org.apache.jasper.el.JspValueExpression.getValue(JspValueExpression.java:107)
    at javax.faces.component.UIComponentBase.isRendered(UIComponentBase.java:390)
    ... 34 more

java.lang.ClassNotFoundException:未找到com.util.WebContextLoader的类加载器

函数类显然有一个名为

com.util.WebContextLoader

的依赖项，该依赖项在其直接类路径邻域中不可用

---

这种情况的间歇性发生表明类路径被散布在类路径上的重复类/库所污染，这些类/库是由不同的类加载器加载的。我开始清理类路径。清除

JRE/lib

、

JRE/lib/ext

和

server/lib

中所有特定于webapp的类/lib

我在这些线程中找到了这个问题的解决方案

解决方案是通过向pom添加以下依赖项，将jasper-el-6.0.18.jar放到war的/web inf/lib文件夹中

org.apache.tomcat 碧玉 6.0.18

---

此依赖关系还将包括“el-api-6.0.18.jar”（请参阅），我们需要排除它

请编辑问题以包含整个stacktrace。请告诉我函数类的确切位置。请同时注册您的Stackoverflow帐户，这是您的第二个帐户，您已经失去了所有历史和声誉！您的第一个帐户在这里：我将web.xml中的javax.faces.STATE\u SAVING\u方法从客户机更改为服务器，这就解决了我目前的问题。我不确定是否要长期保持该设置（可能会对性能产生影响？）。我将web.xml中的javax.faces.STATE\u SAVING\u方法从客户机更改为服务器，这暂时解决了我的问题。我不确定我是否希望长期保持这种设置（可能会对性能产生一些影响？）。很有趣。它基本上只是将组件树存储在客户端而不是服务器端。组件树仍然需要在服务器端恢复（JSF生命周期的第一阶段）。我看不出这是如何解决类加载问题的。也许在同一时刻还有更多的问题是你意外/无意中解决的。现在它可以工作了，试着将它设置回服务器并重新部署/重新启动，看看它是否仍然可以工作。许多人已经发布了关于EL函数类加载问题的帖子。看起来像是JBoss的问题。