Question

我创建了一个简单的xhtml页面，其中包含以下代码（如Primefaces showcase）：

    <body>
    <div>My test</div>

    <h:form>
        <p:messages showDetail="true"/>
        <p:captcha label="Captcha" />
    </h:form>

</body>

加载此页面，我会遇到以下例外情况：

exception

javax.servlet.ServletException: Expression cannot be null
root cause

javax.el.ELException: Expression cannot be null

我的范围是在表单中使用验证码组件，并检查用户是否通过按钮（提交）进行了检查。

这是完整的堆栈跟踪：

严重：错误渲染视图[/test.xhtml] javax.el.ELException：表达式不能为null at com.sun.el.lang.ExpressionBuilder.createNodeInternal（ExpressionBuilder.java:172）在com.sun.el.lang.ExpressionBuilder.build（ExpressionBuilder.java:237） at com.sun.el.lang.ExpressionBuilder.createValueExpression（ExpressionBuilder.java:295） at com.sun.el.ExpressionFactoryImpl.createValueExpression（ExpressionFactoryImpl.java:112）在org.jboss.weld.util.el.ForwardingExpressionFactory.createValueExpression（ForwardingExpressionFactory.java:53）在org.jboss.weld.el.WeldExpressionFactory.createValueExpression（WeldExpressionFactory.java:48） at com.sun.faces.application.ApplicationImpl.evaluateExpressionGet（ApplicationImpl.java:446）在javax.faces.application.ApplicationWrapper.evaluateExpressionGet（ApplicationWrapper.java:684）在org.primefaces.component.captcha.CaptchaRenderer.getPublicKey（CaptchaRenderer.java:87）在org.primefaces.component.captcha.CaptchaRenderer.encodeEnd（CaptchaRenderer.java:50）在javax.faces.component.UIComponentBase.encodeEnd（UIComponentBase.java:919）在javax.faces.component.UIComponent.encodeAll（UIComponent.java:1863）在javax.faces.render.Renderer.encodeChildren（Renderer.java:176）在javax.faces.component.UIComponentBase.encodeChildren（UIComponentBase.java:889）在javax.faces.component.UIComponent.encodeAll（UIComponent.java:1856）在javax.faces.component.UIComponent.encodeAll（UIComponent.java:1859）在com.sun.faces.application.view.FaceletViewHandlingStrategy.renderView（FaceletViewHandlingStrategy.java:456） at com.sun.faces.application.view.MultiViewHandler.renderView（MultiViewHandler.java:133）在javax.faces.application.ViewHandlerWrapper.renderView（ViewHandlerWrapper.java:337） at com.sun.faces.lifecycle.RenderResponsePhase.execute（RenderResponsePhase.java:120）在com.sun.faces.lifecycle.Phase.doPhase（Phase.java:101）在com.sun.faces.lifecycle.LifecycleImpl.render（LifecycleImpl.java:219）在javax.faces.webapp.FacesServlet.service（FacesServlet.java:647）在org.apache.catalina.core.StandardWrapper.service（StandardWrapper.java:1682）在org.apache.catalina.core.StandardWrapperValve.invoke（StandardWrapperValve.java:318） at org.apache.catalina.core.StandardContextValve.invoke（StandardContextValve.java:160）在org.apache.catalina.core.StandardPipeline.doInvoke（StandardPipeline.java:734）在org.apache.catalina.core.StandardPipeline.invoke（StandardPipeline.java:673）在com.sun.enterprise.web.WebPipeline.invoke（WebPipeline.java:99）在org.apache.catalina.core.StandardHostValve.invoke（StandardHostValve.java:174）在org.apache.catalina.connector.CoyoteAdapter.doService（CoyoteAdapter.java:415）在org.apache.catalina.connector.CoyoteAdapter.service（CoyoteAdapter.java:282） at com.sun.enterprise.v3.services.impl.ContainerMapper $ HttpHandlerCallable.call（ContainerMapper.java:459） at com.sun.enterprise.v3.services.impl.ContainerMapper.service（ContainerMapper.java:167）在org.glassfish.grizzly.http.server.HttpHandler.runService（HttpHandler.java:201）在org.glassfish.grizzly.http.server.HttpHandler.doHandle（HttpHandler.java:175）在org.glassfish.grizzly.http.server.HttpServerFilter.handleRead（HttpServerFilter.java:235）在org.glassfish.grizzly.filterchain.ExecutorResolver $ 9.execute（ExecutorResolver.java:119）在org.glassfish.grizzly.filterchain.DefaultFilterChain.executeFilter（DefaultFilterChain.java:284）在org.glassfish.grizzly.filterchain.DefaultFilterChain.executeChainPart（DefaultFilterChain.java:201）在org.glassfish.grizzly.filterchain.DefaultFilterChain.execute（DefaultFilterChain.java:133）在org.glassfish.grizzly.filterchain.DefaultFilterChain.process（DefaultFilterChain.java:112）在org.glassfish.grizzly.ProcessorExecutor.execute（ProcessorExecutor.java:77）在org.glassfish.grizzly.nio.transport.TCPNIOTransport.fireIOEvent（TCPNIOTransport.java:561）在org.glassfish.grizzly.strategies.AbstractIOStrategy.fireIOEvent（AbstractIOStrategy.java:112）在org.glassfish.grizzly.strategies.WorkerThreadIOStrategy.run0（WorkerThreadIOStrategy.java:117）在org.glassfish.grizzly.strategies.WorkerThreadIOStrategy.access $ 100（WorkerThreadIOStrategy.java:56）在org.glassfish.grizzly.strategies.WorkerThreadIOStrategy $ WorkerThreadRunnable.run（WorkerThreadIOStrategy.java:137）在org.glassfish.grizzly.threadpool.AbstractThreadPool $ Worker.doWork（AbstractThreadPool.java:565）在org.glassfish.grizzly.threadpool.AbstractThreadPool $ Worker.run（AbstractThreadPool.java:545）在java.lang.Thread.run（Thread.java:748）信息：找到ExceptionQueuedEvent：true 严重：javax.el.ELException：Expression不能为null at com.sun.el.lang.ExpressionBuilder.createNodeInternal（ExpressionBuilder.java:172）在com.sun.el.lang.ExpressionBuilder.build（ExpressionBuilder.java:237） at com.sun.el.lang.ExpressionBuilder.createValueExpression（ExpressionBuilder.java:295） at com.sun.el.ExpressionFactoryImpl.createValueExpression（ExpressionFactoryImpl.java:112）在org.jboss.weld.util.el.ForwardingExpressionFactory.createValueExpression（ForwardingExpressionFactory.java:53）在org.jboss.weld.el.WeldExpressionFactory.createValueExpression（WeldExpressionFactory.java:48） at com.sun.faces.application.ApplicationImpl.evaluateExpressionGet（ApplicationImpl.java:446）在javax.faces.application.ApplicationWrapper.evaluateExpressionGet（ApplicationWrapper.java:684）在org.primefaces.component.captcha.CaptchaRenderer.getPublicKey（CaptchaRenderer.java:87）在org.primefaces.component.captcha.CaptchaRenderer.encodeEnd（CaptchaRenderer.java:50）在javax.faces.component.UIComponentBase.encodeEnd（UIComponentBase.java:919）在javax.faces.component.UIComponent.encodeAll（UIComponent.java:1863）在javax.faces.render.Renderer.encodeChildren（Renderer.java:176）在javax.faces.component.UIComponentBase.encodeChildren（UIComponentBase.java:889）在javax.faces.component.UIComponent.encodeAll（UIComponent.java:1856）在javax.faces.component.UIComponent.encodeAll（UIComponent.java:1859）在com.sun.faces.application.view.FaceletViewHandlingStrategy.renderView（FaceletViewHandlingStrategy.java:456） at com.sun.faces.application.view.MultiViewHandler.renderView（MultiViewHandler.java:133）在javax.faces.application.ViewHandlerWrapper.renderView（ViewHandlerWrapper.java:337） at com.sun.faces.lifecycle.RenderResponsePhase.execute（RenderResponsePhase.java:120）在com.sun.faces.lifecycle.Phase.doPhase（Phase.java:101）在com.sun.faces.lifecycle.LifecycleImpl.render（LifecycleImpl.java:219）在javax.faces.webapp.FacesServlet.service（FacesServlet.java:647）在org.apache.catalina.core.StandardWrapper.service（StandardWrapper.java:1682）在org.apache.catalina.core.StandardWrapperValve.invoke（StandardWrapperValve.java:318） at org.apache.catalina.core.StandardContextValve.invoke（StandardContextValve.java:160）在org.apache.catalina.core.StandardPipeline.doInvoke（StandardPipeline.java:734）在org.apache.catalina.core.StandardPipeline.invoke（StandardPipeline.java:673）在com.sun.enterprise.web.WebPipeline.invoke（WebPipeline.java:99）在org.apache.catalina.core.StandardHostValve.invoke（StandardHostValve.java:174）在org.apache.catalina.connector.CoyoteAdapter.doService（CoyoteAdapter.java:415）在org.apache.catalina.connector.CoyoteAdapter.service（CoyoteAdapter.java:282） at com.sun.enterprise.v3.services.impl.ContainerMapper $ HttpHandlerCallable.call（ContainerMapper.java:459） at com.sun.enterprise.v3.services.impl.ContainerMapper.service（ContainerMapper.java:167）在org.glassfish.grizzly.http.server.HttpHandler.runService（HttpHandler.java:201）在org.glassfish.grizzly.http.server.HttpHandler.doHandle（HttpHandler.java:175）在org.glassfish.grizzly.http.server.HttpServerFilter.handleRead（HttpServerFilter.java:235）在org.glassfish.grizzly.filterchain.ExecutorResolver $ 9.execute（ExecutorResolver.java:119）在org.glassfish.grizzly.filterchain.DefaultFilterChain.executeFilter（DefaultFilterChain.java:284）在org.glassfish.grizzly.filterchain.DefaultFilterChain.executeChainPart（DefaultFilterChain.java:201）在org.glassfish.grizzly.filterchain.DefaultFilterChain.execute（DefaultFilterChain.java:133）在org.glassfish.grizzly.filterchain.DefaultFilterChain.process（DefaultFilterChain.java:112）在org.glassfish.grizzly.ProcessorExecutor.execute（ProcessorExecutor.java:77）在org.glassfish.grizzly.nio.transport.TCPNIOTransport.fireIOEvent（TCPNIOTransport.java:561）在org.glassfish.grizzly.strategies.AbstractIOStrategy.fireIOEvent（AbstractIOStrategy.java:112）在org.glassfish.grizzly.strategies.WorkerThreadIOStrategy.run0（WorkerThreadIOStrategy.java:117）在org.glassfish.grizzly.strategies.WorkerThreadIOStrategy.access $ 100（WorkerThreadIOStrategy.java:56）在org.glassfish.grizzly.strategies.WorkerThreadIOStrategy $ WorkerThreadRunnable.run（WorkerThreadIOStrategy.java:137）在org.glassfish.grizzly.threadpool.AbstractThreadPool $ Worker.doWork（AbstractThreadPool.java:565）在org.glassfish.grizzly.threadpool.AbstractThreadPool $ Worker.run（AbstractThreadPool.java:545）在java.lang.Thread.run（Thread.java:748）警告：StandardWrapperValve [Faces Servlet]：用于servlet的Servlet.service（）Faces Servlet抛出异常

Answer 1

您必须转到https://www.google.com/recaptcha/admin

获取私钥和公钥，然后使用

在web.xml中注册

<context-param>
        <param-name>primefaces.PUBLIC_CAPTCHA_KEY</param-name>
        <param-value>PUBLIC_KEY</param-value>
</context-param>

<context-param>
        <param-name>primefaces.PRIVATE_CAPTCHA_KEY</param-name>
        <param-value>PRIVATE_KEY</param-value>
</context-param>

Primefaces 5：验证码不适用于＆＃39; javax.servlet.ServletException：表达式不能为空＆＃39;

1 个答案: