Servlet.service() 用于 servlet [Faces Servlet] 和错误渲染视图

Question

当我在 Eclipse 上运行动态 web 项目时，我在控制台上收到以下错误。 如何解决此错误？ 我在 NewUserBean class 中创建了 @ManagedBean(name = "newUserBean") 并且我在 xhtml 文件中调用 newUserBean。 我没有向 face-config.xml 添加任何内容

    Kas 30, 2021 11:11:06 AM com.sun.faces.application.view.FaceletViewHandlingStrategy handleRenderException
SEVERE: Error Rendering View[/index.xhtml]
javax.el.ELException: /index.xhtml: java.lang.NullPointerException
    at com.sun.faces.facelets.compiler.AttributeInstruction.write(AttributeInstruction.java:94)
    at com.sun.faces.facelets.compiler.UIInstructions.encodeBegin(UIInstructions.java:82)
    at com.sun.faces.facelets.compiler.UILeaf.encodeAll(UILeaf.java:183)
    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 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.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:199)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:543)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:139)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:81)
    at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:688)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343)
    at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:609)
    at com.sun.faces.facelets.compiler.AttributeInstruction.write(AttributeInstruction.java:89)
    ... 31 more

Kas 30, 2021 11:11:06 AM org.apache.catalina.core.StandardWrapperValve invoke
SEVERE: Servlet.service() for servlet [Faces Servlet] in context with path [/Aident] threw exception [null] with root cause
java.lang.NullPointerException
    at createBeans.NewUserBean.createUser(NewUserBean.java:159)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
    at java.lang.Thread.run(Thread.java:748)

编辑web 页面屏幕出现了，但是当我在 xhtml 文件中的注册按钮上键入 actionListener="#{newUserBean.createUser()}" 时，没有出现 web 页面，只出现一个白屏。

错误

2021 年 3 月 30 日下午 12:03:09 com.sun.faces.application.view.FaceletViewHandlingStrategy handleRenderException 严重：渲染视图时出错 [/index.xhtml]

Kas 30, 2021 12:03:09 PM com.sun.faces.context.ExceptionHandlerImpl throwIt 信息：处理尝试重置响应的错误时出现异常。

2021 年 3 月 30 日下午 12:03:09 org.apache.catalina.core.StandardWrapperValve 调用严重：Servlet.service() for servlet [Faces Servlet] 在路径 [/Aident] 的上下文中抛出异常 [null] 和根本原因