如何解决Failed to start component [StandardEngine[Catalina].StandardHost[127.0.0.1].StandardContext[]]问题

调试web项目，项目部署到tomcat，报如下错误：

 java.util.concurrent.ExecutionException: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[127.0.0.1].StandardContext[]]
     at java.util.concurrent.FutureTask.report(FutureTask.java:122)
     at java.util.concurrent.FutureTask.get(FutureTask.java:192)
     at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:911)
     at org.apache.catalina.core.StandardHost.startInternal(StandardHost.java:890)
     at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
     at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1403)
     at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1393)
     at java.util.concurrent.FutureTask.run(FutureTask.java:266)
     at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
     at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
     at java.lang.Thread.run(Thread.java:745)
 Caused by: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[127.0.0.1].StandardContext[]]
     at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:167)
     ... 6 more
 Caused by: org.apache.catalina.LifecycleException: Failed to start component [org.apache.catalina.webresources.StandardRoot@1df93418]
     at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:167)
     at org.apache.catalina.core.StandardContext.resourcesStart(StandardContext.java:4842)
     at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:4974)
     at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
     ... 6 more
 Caused by: java.lang.IllegalArgumentException: The main resource set specified [C:\Users\Lzj\.IntelliJIdea2016.2\system\tomcat\Unnamed_question\webapps\call] is not valid
     at org.apache.catalina.webresources.StandardRoot.createMainResourceSet(StandardRoot.java:732)
     at org.apache.catalina.webresources.StandardRoot.startInternal(StandardRoot.java:690)
     at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
     ... 9 more
 
 22-Oct-2017 17:00:28.227 严重 [main] org.apache.catalina.core.ContainerBase.startInternal A child container failed during start
  java.util.concurrent.ExecutionException: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[127.0.0.1]]
     at java.util.concurrent.FutureTask.report(FutureTask.java:122)
     at java.util.concurrent.FutureTask.get(FutureTask.java:192)
     at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:911)
     at org.apache.catalina.core.StandardEngine.startInternal(StandardEngine.java:262)
     at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
     at org.apache.catalina.core.StandardService.startInternal(StandardService.java:422)
     at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
     at org.apache.catalina.core.StandardServer.startInternal(StandardServer.java:791)
     at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
     at org.apache.catalina.startup.Catalina.start(Catalina.java:655)
     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:355)
     at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:495)
 Caused by: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[127.0.0.1]]
     at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:167)
     at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1403)
     at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1393)
     at java.util.concurrent.FutureTask.run(FutureTask.java:266)
     at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
     at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
     at java.lang.Thread.run(Thread.java:745)
 Caused by: org.apache.catalina.LifecycleException: A child container failed during start
     at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:919)
     at org.apache.catalina.core.StandardHost.startInternal(StandardHost.java:890)
     at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
     ... 6 more
 
 22-Oct-2017 17:00:28.230 严重 [main] org.apache.catalina.startup.Catalina.start The required Server component failed to start so Tomcat is unable to start.
  org.apache.catalina.LifecycleException: Failed to start component [StandardServer[8005]]
     at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:167)
     at org.apache.catalina.startup.Catalina.start(Catalina.java:655)
     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:355)
     at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:495)
 Caused by: org.apache.catalina.LifecycleException: Failed to start component [StandardService[Catalina]]
     at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:167)
     at org.apache.catalina.core.StandardServer.startInternal(StandardServer.java:791)
     at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
     ... 7 more
 Caused by: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina]]
     at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:167)
     at org.apache.catalina.core.StandardService.startInternal(StandardService.java:422)
     at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
     ... 9 more
 Caused by: org.apache.catalina.LifecycleException: A child container failed during start
     at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:919)
     at org.apache.catalina.core.StandardEngine.startInternal(StandardEngine.java:262)
     at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
     ... 11 more

最后发现是tomcat安装目录/conf/server.xml配置的问题：

因为我之前配置了:

    <Engine>
      <Host name="127.0.0.1" debug="0" appBase="webapps" unpackWARs="true" autoDeploy="true" xmlValidation="false"  xmlNamespaceAware="false">
        <Context path="" docBase="call" debug="0" reloadable="true" crossContext="true"/>
        <Logger className="org.apache.catalina.logger.FileLogger" directory="logs" prefix="tot_log." suffix=".txt" timestamp="true"/>
      </Host>
    </Engine>

将这个Host节点注释，问题解决。