console窗口错误输出：
严重: A child container failed during start java.util.concurrent.ExecutionException: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost].StandardContext[/syncW]] at java.util.concurrent.FutureTask.report(Unknown Source) at java.util.concurrent.FutureTask.get(Unknown Source) at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:1119) at org.apache.catalina.core.StandardHost.startInternal(StandardHost.java:819) at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:145) at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1571) at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1561) at java.util.concurrent.FutureTask.run(Unknown Source) at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source) at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source) at java.lang.Thread.run(Unknown Source) Caused by: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost].StandardContext[/syncW]] at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:162) ... 6 more Caused by: java.lang.NoClassDefFoundError: Lorg/apache/logging/log4j/Logger; at java.lang.Class.getDeclaredFields0(Native Method) at java.lang.Class.privateGetDeclaredFields(Unknown Source) at java.lang.Class.getDeclaredFields(Unknown Source) at org.apache.catalina.util.Introspection.getDeclaredFields(Introspection.java:106) at org.apache.catalina.startup.WebAnnotationSet.loadFieldsAnnotation(WebAnnotationSet.java:270) at org.apache.catalina.startup.WebAnnotationSet.loadApplicationFilterAnnotations(WebAnnotationSet.java:109) at org.apache.catalina.startup.WebAnnotationSet.loadApplicationAnnotations(WebAnnotationSet.java:64) at org.apache.catalina.startup.ContextConfig.applicationAnnotationsConfig(ContextConfig.java:417) at org.apache.catalina.startup.ContextConfig.configureStart(ContextConfig.java:891) at org.apache.catalina.startup.ContextConfig.lifecycleEvent(ContextConfig.java:388) at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:117) at org.apache.catalina.util.LifecycleBase.fireLifecycleEvent(LifecycleBase.java:90) at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5522) at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:145) ... 6 more Caused by: java.lang.ClassNotFoundException: org.apache.logging.log4j.Logger at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1892) at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1735) ... 20 more 五月 03, 2017 11:27:59 下午 org.apache.catalina.core.ContainerBase startInternal 严重: A child container failed during start java.util.concurrent.ExecutionException: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost]] at java.util.concurrent.FutureTask.report(Unknown Source) at java.util.concurrent.FutureTask.get(Unknown Source) at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:1119) at org.apache.catalina.core.StandardEngine.startInternal(StandardEngine.java:300) at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:145) at org.apache.catalina.core.StandardService.startInternal(StandardService.java:444) at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:145) at org.apache.catalina.core.StandardServer.startInternal(StandardServer.java:758) at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:145) at org.apache.catalina.startup.Catalina.start(Catalina.java:693) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) at java.lang.reflect.Method.invoke(Unknown Source) at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:294) at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:428) Caused by: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost]] at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:162) at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1571) at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1561) at java.util.concurrent.FutureTask.run(Unknown Source) at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source) at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source) at java.lang.Thread.run(Unknown Source) Caused by: org.apache.catalina.LifecycleException: A child container failed during start at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:1127) at org.apache.catalina.core.StandardHost.startInternal(StandardHost.java:819) at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:145) ... 6 more 五月 03, 2017 11:27:59 下午 org.apache.catalina.startup.Catalina start 严重: 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:162) at org.apache.catalina.startup.Catalina.start(Catalina.java:693) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) at java.lang.reflect.Method.invoke(Unknown Source) at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:294) at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:428) Caused by: org.apache.catalina.LifecycleException: Failed to start component [StandardService[Catalina]] at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:162) at org.apache.catalina.core.StandardServer.startInternal(StandardServer.java:758) at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:145) ... 7 more Caused by: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina]] at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:162) at org.apache.catalina.core.StandardService.startInternal(StandardService.java:444) at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:145) ... 9 more Caused by: org.apache.catalina.LifecycleException: A child container failed during start at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:1127) at org.apache.catalina.core.StandardEngine.startInternal(StandardEngine.java:300) at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:145) ... 11 more 五月 03, 2017 11:27:59 下午 org.apache.coyote.AbstractProtocol pause 信息: Pausing ProtocolHandler ["http-apr-8080"] 五月 03, 2017 11:27:59 下午 org.apache.coyote.AbstractProtocol pause 信息: Pausing ProtocolHandler ["ajp-apr-8009"] 五月 03, 2017 11:27:59 下午 org.apache.catalina.core.StandardService stopInternal 信息: Stopping service Catalina 五月 03, 2017 11:27:59 下午 org.apache.coyote.AbstractProtocol destroy 信息: Destroying ProtocolHandler ["http-apr-8080"] 五月 03, 2017 11:27:59 下午 org.apache.coyote.AbstractProtocol destroy 信息: Destroying ProtocolHandler ["ajp-apr-8009"]其实根本问题在于：
Caused by: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost].StandardContext[/syncW]] at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:162) ... 6 more Caused by: java.lang.NoClassDefFoundError: Lorg/apache/logging/log4j/Logger; at java.lang.Class.getDeclaredFields0(Native Method) at java.lang.Class.privateGetDeclaredFields(Unknown Source) at java.lang.Class.getDeclaredFields(Unknown Source) at org.apache.catalina.util.Introspection.getDeclaredFields(Introspection.java:106) at org.apache.catalina.startup.WebAnnotationSet.loadFieldsAnnotation(WebAnnotationSet.java:270) at org.apache.catalina.startup.WebAnnotationSet.loadApplicationFilterAnnotations(WebAnnotationSet.java:109) at org.apache.catalina.startup.WebAnnotationSet.loadApplicationAnnotations(WebAnnotationSet.java:64) at org.apache.catalina.startup.ContextConfig.applicationAnnotationsConfig(ContextConfig.java:417) at org.apache.catalina.startup.ContextConfig.configureStart(ContextConfig.java:891) at org.apache.catalina.startup.ContextConfig.lifecycleEvent(ContextConfig.java:388) at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:117) at org.apache.catalina.util.LifecycleBase.fireLifecycleEvent(LifecycleBase.java:90) at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5522) at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:145) ... 6 more Caused by: java.lang.ClassNotFoundException: org.apache.logging.log4j.Logger at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1892) at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1735) ... 20 more注意到org.apache.logging.log4j.logger中出现错误，其实是找不到所用到的类。 解决方法： 在WEB-INF里面的lib文件夹中缺少对Struts2的log4j-api-2.7.jar的引用，将log4j-api-2.7.jar放进去后运行成功。
在网上也有很多人出现过“在Eclipse中tomcat不部署项目启动正常，部署一个项目启动报异常”的问题，可能引起这个问题的原因不尽相同，但是只要在输出错误信息中探索应该可以找到原因，要坚持与之斗争。
