Question

我正在尝试使用netbeans运行jsf应用程序并在URLEncode中具有NullPointerException的这个例外。我认为Servlet存在一些问题，但我不知道如何修复它来源：https://github.com/agoncal/agoncal-application-petstore-ee6

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="3.0" 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-app_3_0.xsd">


    <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>

    <welcome-file-list>
        <welcome-file>index.html</welcome-file>
    </welcome-file-list>

java.lang.NullPointerException
        at java.net.URLEncoder.encode(URLEncoder.java:204)
        at com.sun.faces.context.UrlBuilder.addValuesToParameter(UrlBuilder.java:318)
        at com.sun.faces.context.UrlBuilder.addParameters(UrlBuilder.java:127)
        at com.sun.faces.context.ExternalContextImpl.encodeBookmarkableURL(ExternalContextImpl.java:1054)
        at com.sun.faces.application.view.MultiViewHandler.getBookmarkableURL(MultiViewHandler.java:407)
        at javax.faces.application.ViewHandlerWrapper.getBookmarkableURL(ViewHandlerWrapper.java:272)
        at org.jboss.weld.jsf.ConversationAwareViewHandler.getBookmarkableURL(ConversationAwareViewHandler.java:132)
        at com.sun.faces.renderkit.html_basic.OutcomeTargetRenderer.getEncodedTargetURL(OutcomeTargetRenderer.java:194)
        at com.sun.faces.renderkit.html_basic.OutcomeTargetLinkRenderer.renderAsActive(OutcomeTargetLinkRenderer.java:158)
        at com.sun.faces.renderkit.html_basic.OutcomeTargetLinkRenderer.encodeBegin(OutcomeTargetLinkRenderer.java:96)
        at javax.faces.component.UIComponentBase.encodeBegin(UIComponentBase.java:864)
        at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1854)
        at javax.faces.render.Renderer.encodeChildren(Renderer.java:176)
        at javax.faces.component.UIComponentBase.encodeChildren(UIComponentBase.java:889)
        at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1856)
        at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1859)
        at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1859)
        at com.sun.faces.application.view.FaceletViewHandlingStrategy.renderView(FaceletViewHandlingStrategy.java:456)
        at com.sun.faces.application.view.MultiViewHandler.renderView(MultiViewHandler.java:133)
        at javax.faces.application.ViewHandlerWrapper.renderView(ViewHandlerWrapper.java:337)
        at com.sun.faces.lifecycle.RenderResponsePhase.execute(RenderResponsePhase.java:120)
        at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101)
        at com.sun.faces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:219)
        at javax.faces.webapp.FacesServlet.service(FacesServlet.java:647)
        at org.apache.catalina.core.StandardWrapper.service(StandardWrapper.java:1682)
        at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:318)
        at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:160)
        at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:734)
        at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:673)
        at com.sun.enterprise.web.WebPipeline.invoke(WebPipeline.java:99)
        at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:174)
        at org.apache.catalina.connector.CoyoteAdapter.doService(CoyoteAdapter.java:415)
        at 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)
        at org.glassfish.grizzly.http.server.HttpHandler.runService(HttpHandler.java:201)
        at org.glassfish.grizzly.http.server.HttpHandler.doHandle(HttpHandler.java:175)
        at org.glassfish.grizzly.http.server.HttpServerFilter.handleRead(HttpServerFilter.java:235)
        at org.glassfish.grizzly.filterchain.ExecutorResolver$9.execute(ExecutorResolver.java:119)
        at org.glassfish.grizzly.filterchain.DefaultFilterChain.executeFilter(DefaultFilterChain.java:284)
        at org.glassfish.grizzly.filterchain.DefaultFilterChain.executeChainPart(DefaultFilterChain.java:201)
        at org.glassfish.grizzly.filterchain.DefaultFilterChain.execute(DefaultFilterChain.java:133)
        at org.glassfish.grizzly.filterchain.DefaultFilterChain.process(DefaultFilterChain.java:112)
        at org.glassfish.grizzly.ProcessorExecutor.execute(ProcessorExecutor.java:77)
        at org.glassfish.grizzly.nio.transport.TCPNIOTransport.fireIOEvent(TCPNIOTransport.java:561)
        at org.glassfish.grizzly.strategies.AbstractIOStrategy.fireIOEvent(AbstractIOStrategy.java:112)
        at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy.run0(WorkerThreadIOStrategy.java:117)
        at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy.access$100(WorkerThreadIOStrategy.java:56)
        at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy$WorkerThreadRunnable.run(WorkerThreadIOStrategy.java:137)
        at org.glassfish.grizzly.threadpool.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:565)
        at org.glassfish.grizzly.threadpool.AbstractThreadPool$Worker.run(AbstractThreadPool.java:545)
        at java.lang.Thread.run(Thread.java:745)

    Warning:   StandardWrapperValve[Faces Servlet]: Servlet.service() for servlet Faces Servlet threw exception
    java.lang.NullPointerException
        at java.net.URLEncoder.encode(URLEncoder.java:204)
        at com.sun.faces.context.UrlBuilder.addValuesToParameter(UrlBuilder.java:318)
        at com.sun.faces.context.UrlBuilder.addParameters(UrlBuilder.java:127)
        at com.sun.faces.context.ExternalContextImpl.encodeBookmarkableURL(ExternalContextImpl.java:1054)
        at com.sun.faces.application.view.MultiViewHandler.getBookmarkableURL(MultiViewHandler.java:407)
        at javax.faces.application.ViewHandlerWrapper.getBookmarkableURL(ViewHandlerWrapper.java:272)
        at org.jboss.weld.jsf.ConversationAwareViewHandler.getBookmarkableURL(ConversationAwareViewHandler.java:132)
        at com.sun.faces.renderkit.html_basic.OutcomeTargetRenderer.getEncodedTargetURL(OutcomeTargetRenderer.java:194)
        at com.sun.faces.renderkit.html_basic.OutcomeTargetLinkRenderer.renderAsActive(OutcomeTargetLinkRenderer.java:158)
        at com.sun.faces.renderkit.html_basic.OutcomeTargetLinkRenderer.encodeBegin(OutcomeTargetLinkRenderer.java:96)
        at javax.faces.component.UIComponentBase.encodeBegin(UIComponentBase.java:864)
        at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1854)
        at javax.faces.render.Renderer.encodeChildren(Renderer.java:176)
        at javax.faces.component.UIComponentBase.encodeChildren(UIComponentBase.java:889)
        at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1856)
        at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1859)
        at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1859)
        at com.sun.faces.application.view.FaceletViewHandlingStrategy.renderView(FaceletViewHandlingStrategy.java:456)
        at com.sun.faces.application.view.MultiViewHandler.renderView(MultiViewHandler.java:133)
        at javax.faces.application.ViewHandlerWrapper.renderView(ViewHandlerWrapper.java:337)
        at com.sun.faces.lifecycle.RenderResponsePhase.execute(RenderResponsePhase.java:120)
        at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101)
        at com.sun.faces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:219)
        at javax.faces.webapp.FacesServlet.service(FacesServlet.java:647)
        at org.apache.catalina.core.StandardWrapper.service(StandardWrapper.java:1682)
        at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:318)
        at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:160)
        at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:734)
        at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:673)
        at com.sun.enterprise.web.WebPipeline.invoke(WebPipeline.java:99)
        at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:174)
        at org.apache.catalina.connector.CoyoteAdapter.doService(CoyoteAdapter.java:415)
        at 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)
        at org.glassfish.grizzly.http.server.HttpHandler.runService(HttpHandler.java:201)
        at org.glassfish.grizzly.http.server.HttpHandler.doHandle(HttpHandler.java:175)
        at org.glassfish.grizzly.http.server.HttpServerFilter.handleRead(HttpServerFilter.java:235)
        at org.glassfish.grizzly.filterchain.ExecutorResolver$9.execute(ExecutorResolver.java:119)
        at org.glassfish.grizzly.filterchain.DefaultFilterChain.executeFilter(DefaultFilterChain.java:284)
        at org.glassfish.grizzly.filterchain.DefaultFilterChain.executeChainPart(DefaultFilterChain.java:201)
        at org.glassfish.grizzly.filterchain.DefaultFilterChain.execute(DefaultFilterChain.java:133)
        at org.glassfish.grizzly.filterchain.DefaultFilterChain.process(DefaultFilterChain.java:112)
        at org.glassfish.grizzly.ProcessorExecutor.execute(ProcessorExecutor.java:77)
        at org.glassfish.grizzly.nio.transport.TCPNIOTransport.fireIOEvent(TCPNIOTransport.java:561)
        at org.glassfish.grizzly.strategies.AbstractIOStrategy.fireIOEvent(AbstractIOStrategy.java:112)
        at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy.run0(WorkerThreadIOStrategy.java:117)
        at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy.access$100(WorkerThreadIOStrategy.java:56)
        at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy$WorkerThreadRunnable.run(WorkerThreadIOStrategy.java:137)
        at org.glassfish.grizzly.threadpool.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:565)
        at org.glassfish.grizzly.threadpool.AbstractThreadPool$Worker.run(AbstractThreadPool.java:545)
        at java.lang.Thread.run(Thread.java:745)

当我去index.xhtml

时

Answer 1

从下到上阅读堆栈跟踪并选择相关的线条以了解流程。

    at javax.faces.webapp.FacesServlet.service(FacesServlet.java:647)

因此，调用FacesServlet并为请求提供服务。

    at com.sun.faces.lifecycle.RenderResponsePhase.execute(RenderResponsePhase.java:120

因此，执行渲染响应阶段。

    at com.sun.faces.application.view.FaceletViewHandlingStrategy.renderView(FaceletViewHandlingStrategy.java:456)

因此将呈现Facelets（XHTML）文件。

    at com.sun.faces.renderkit.html_basic.OutcomeTargetLinkRenderer.encodeBegin(OutcomeTargetLinkRenderer.java:96)

因此，正在呈现<h:link>。

    at com.sun.faces.renderkit.html_basic.OutcomeTargetRenderer.getEncodedTargetURL(OutcomeTargetRenderer.java:194)

因此，它需要呈现目标URL。

    at com.sun.faces.context.UrlBuilder.addParameters(UrlBuilder.java:127)

因此，该链接具有<f:param>值，需要将其添加到目标网址。

    at java.net.URLEncoder.encode(URLEncoder.java:204)

他们需要进行URL编码。

java.lang.NullPointerException

但是，value <f:param>的{{1}}似乎是<h:link>。

我想你现在明白了吗？

Answer 2

从GlassFish 4.0（NetBeans 7）迁移到GlassFish 4.1（NetBeans 8）时出现了这样的问题。究其原因是<f:param>应该没有空值。在GlassFish 4.0中，这不是问题，只是参数未添加到生成的链接。但是，当NullPointerException中的值为null时，GlassFish 4.1具有不同的jsf实现，并且<f:param>失败。

作为我接下来做的修复。而不是<f:param value="#{myBean.field}"/> 我用了<f:param value="#{not empty myBean.field ? myBean.field : ''}"/> 仅使用属性rendered无济于事。或者它可以用<c:if>舍入，如：

<c:if test="#{not empty myBean.field}">
    <f:param value="#{myBean.field}"/>
</c:if>

Answer 3

我通过对f：param使用disable参数解决了这个问题。该代码适用于Payara 5（基于Glassfish）。

<h:link outcome="nextpage" value="click here">
    <f:param name="id" value="#{myBean.id}" disable="#{empty myBean.id}"/>
</h:link>

如果参数“ id”为null或为空，则不会将其添加到网址中。

如果参数为空时该链接没有意义，您也可以禁用整个链接，它将变成常规文本（），请注意，禁用h：link的参数而不是disable：

<h:link outcome="nextpage" value="click here" disabled="#{empty myBean.id}">
    <f:param name="id" value="#{myBean.id}"/>
</h:link>

两种解决方案都避免在URLEncoder.encode上出现NullPointerException。

java.net.URLEncoder.encode的java.lang.NullPointerException，地址为com.sun.faces.context.UrlBuilder.addValuesToParameter

3 个答案: