Tomcat 部署：无法找到实现 AppShellConfigurator 的单个类

Question

在 tomcat 中部署 vaadin 应用程序期间，出现异常：

06-Mar-2022 17:54:53.990 GRAVE [main] org.apache.catalina.startup.HostConfig.deployWAR Error durante el despliegue del archivo [/u01/tomcat/apache-t$
        java.lang.IllegalStateException: Error starting child
                at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:720)
                at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:690)
                at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:705)
                at org.apache.catalina.startup.HostConfig.deployWAR(HostConfig.java:978)
                at org.apache.catalina.startup.HostConfig$DeployWar.run(HostConfig.java:1849)
                at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
                at java.util.concurrent.FutureTask.run(FutureTask.java:266)
                at org.apache.tomcat.util.threads.InlineExecutorService.execute(InlineExecutorService.java:75)
                at java.util.concurrent.AbstractExecutorService.submit(AbstractExecutorService.java:112)
                at org.apache.catalina.startup.HostConfig.deployWARs(HostConfig.java:773)
                at org.apache.catalina.startup.HostConfig.deployApps(HostConfig.java:427)
                at org.apache.catalina.startup.HostConfig.start(HostConfig.java:1576)

              at org.apache.catalina.util.LifecycleBase.setState(LifecycleBase.java:366)
                at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:936)
                at org.apache.catalina.core.StandardHost.startInternal(StandardHost.java:841)
                at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
                at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1384)
                at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1374)
                at java.util.concurrent.FutureTask.run(FutureTask.java:266)
                at org.apache.tomcat.util.threads.InlineExecutorService.execute(InlineExecutorService.java:75)
                at java.util.concurrent.AbstractExecutorService.submit(AbstractExecutorService.java:134)
                at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:909)
                at org.apache.catalina.core.StandardEngine.startInternal(StandardEngine.java:262)
                at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
                at org.apache.catalina.core.StandardService.startInternal(StandardService.java:421)
                at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
                at org.apache.catalina.core.StandardServer.startInternal(StandardServer.java:930)
                at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
                at org.apache.catalina.startup.Catalina.start(Catalina.java:633)
                at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
                at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
                at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
                at java.lang.reflect.Method.invoke(Method.java:498)
                at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:343)
                at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:474)
        Caused by: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost].StandardConte$
                at org.apache.catalina.util.LifecycleBase.handleSubClassException(LifecycleBase.java:440)
                at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:198)
                at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:717)
                ... 37 more
        Caused by: com.vaadin.flow.server.InvalidApplicationConfigurationException:

Unable to find a single class implementing `AppShellConfigurator` from the following candidates:
Unable to find a single class implementing `AppShellConfigurator` from the following candidates:
  com.example.application.Application
  com.example.application.views.MainLayout$AppShell

                at com.vaadin.flow.server.AppShellRegistry.setShell(AppShellRegistry.java:140)
                at com.vaadin.flow.server.startup.VaadinAppShellInitializer.lambda$init$1(VaadinAppShellInitializer.java:134)
                at java.util.stream.ForEachOps$ForEachOp$OfRef.accept(ForEachOps.java:184)
                at java.util.stream.SortedOps$SizedRefSortingSink.end(SortedOps.java:352)
                at java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:483)
                at java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:472)
                at java.util.stream.ForEachOps$ForEachOp.evaluateSequential(ForEachOps.java:151)
                at java.util.stream.ForEachOps$ForEachOp$OfRef.evaluateSequential(ForEachOps.java:174)
                at java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
                at java.util.stream.ReferencePipeline.forEach(ReferencePipeline.java:418)
                at com.vaadin.flow.server.startup.VaadinAppShellInitializer.init(VaadinAppShellInitializer.java:132)
                at com.vaadin.flow.server.startup.VaadinAppShellInitializer.initialize(VaadinAppShellInitializer.java:79)
                at com.vaadin.flow.server.startup.VaadinServletContextStartupInitializer.process(VaadinServletContextStartupInitializer.java:42)
                at com.vaadin.flow.server.startup.ClassLoaderAwareServletContainerInitializer.lambda$onStartup$2(ClassLoaderAwareServletCo ....

OS : Linux 服务器：9.0.30.0 Vaadin：V 22.0.2

使用 vaadin 14 版本时，我没有遇到这个问题。

Answer 1

如 文档，

整个 Vaadin 应用程序必须有一个应用程序 shell，因此不能有多个类实现 AppShellConfigurator。

您的应用程序有两个实现 AppShellConfigurator 的类。

确保您的应用程序只有一个实现 AppShellConfigurator 的类，并将注释移至该类：@Viewport、@PageTitle、<代码>@BodySize、@Meta、@Inline、@PWA 和 @Push。