解决Tomcat v8.0 Server at localhost failed to start.

SEVERE: A child container failed during start。

java.util.concurrent.ExecutionException: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost].StandardContext[/appserver]]

at java.util.concurrent.FutureTask$Sync.innerGet(Unknown Source)

at java.util.concurrent.FutureTask.get(Unknown Source)

at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:917)

at org.apache.catalina.core.StandardHost.startInternal(StandardHost.java:871)

at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)

at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1409)

at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1399)

at java.util.concurrent.FutureTask$Sync.innerRun(Unknown Source)

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[/appserver]]

at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:154)

... 7 more

Caused by: java.lang.IllegalArgumentException: Invalid <url-pattern> a/app in servlet mapping

at org.apache.catalina.core.StandardContext.addServletMapping(StandardContext.java:3075)

at org.apache.catalina.core.StandardContext.addServletMapping(StandardContext.java:3050)

at org.apache.catalina.startup.ContextConfig.configureContext(ContextConfig.java:1372)

at org.apache.catalina.startup.ContextConfig.webConfig(ContextConfig.java:1176)

at org.apache.catalina.startup.ContextConfig.configureStart(ContextConfig.java:771)

at org.apache.catalina.startup.ContextConfig.lifecycleEvent(ContextConfig.java:305)

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:5065)

at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)

... 7 more

十月 14, 2015 5:15:02 下午 org.apache.catalina.core.ContainerBase startInternal

SEVERE: 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$Sync.innerGet(Unknown Source)

at java.util.concurrent.FutureTask.get(Unknown Source)

at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:917)

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:439)

at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)

at org.apache.catalina.core.StandardServer.startInternal(StandardServer.java:769)

at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)

at org.apache.catalina.startup.Catalina.start(Catalina.java:625)

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:351)

at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:485)

Caused by: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost]]

at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:154)

at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1409)

at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1399)

at java.util.concurrent.FutureTask$Sync.innerRun(Unknown Source)

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:925)

at org.apache.catalina.core.StandardHost.startInternal(StandardHost.java:871)

at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)

... 7 more

十月 14, 2015 5:15:02 下午 org.apache.catalina.startup.Catalina start

SEVERE: 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:154)

at org.apache.catalina.startup.Catalina.start(Catalina.java:625)

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:351)

at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:485)

Caused by: org.apache.catalina.LifecycleException: Failed to start component [StandardService[Catalina]]

at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:154)

at org.apache.catalina.core.StandardServer.startInternal(StandardServer.java:769)

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:154)

at org.apache.catalina.core.StandardService.startInternal(StandardService.java:439)

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:925)

at org.apache.catalina.core.StandardEngine.startInternal(StandardEngine.java:262)

at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)

... 11 more

十月 14, 2015 5:15:02 下午 org.apache.coyote.AbstractProtocol pause

INFO: Pausing ProtocolHandler ["http-nio-8080"]

十月 14, 2015 5:15:02 下午 org.apache.coyote.AbstractProtocol pause

INFO: Pausing ProtocolHandler ["ajp-nio-8009"]

十月 14, 2015 5:15:02 下午 org.apache.catalina.core.StandardService stopInternal

INFO: Stopping service Catalina

十月 14, 2015 5:15:02 下午 org.apache.coyote.AbstractProtocol destroy

INFO: Destroying ProtocolHandler ["http-nio-8080"]

十月 14, 2015 5:15:02 下午 org.apache.coyote.AbstractProtocol destroy

SEVERE: Failed to destroy end point associated with ProtocolHandler ["http-nio-8080"]

java.lang.NullPointerException

at org.apache.tomcat.util.net.NioEndpoint.releaseCaches(NioEndpoint.java:302)

at org.apache.tomcat.util.net.NioEndpoint.unbind(NioEndpoint.java:473)

at org.apache.tomcat.util.net.AbstractEndpoint.destroy(AbstractEndpoint.java:818)

at org.apache.coyote.AbstractProtocol.destroy(AbstractProtocol.java:532)

at org.apache.catalina.connector.Connector.destroyInternal(Connector.java:1023)

at org.apache.catalina.util.LifecycleBase.destroy(LifecycleBase.java:305)

at org.apache.catalina.core.StandardService.destroyInternal(StandardService.java:588)

at org.apache.catalina.util.LifecycleBase.destroy(LifecycleBase.java:305)

at org.apache.catalina.core.StandardServer.destroyInternal(StandardServer.java:859)

at org.apache.catalina.util.LifecycleBase.destroy(LifecycleBase.java:305)

at org.apache.catalina.startup.Catalina.start(Catalina.java:629)

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:351)

at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:485)

十月 14, 2015 5:15:02 下午 org.apache.coyote.AbstractProtocol destroy

INFO: Destroying ProtocolHandler ["ajp-nio-8009"]

十月 14, 2015 5:15:02 下午 org.apache.coyote.AbstractProtocol destroy

SEVERE: Failed to destroy end point associated with ProtocolHandler ["ajp-nio-8009"]

java.lang.NullPointerException

at org.apache.tomcat.util.net.NioEndpoint.releaseCaches(NioEndpoint.java:302)

at org.apache.tomcat.util.net.NioEndpoint.unbind(NioEndpoint.java:473)

at org.apache.tomcat.util.net.AbstractEndpoint.destroy(AbstractEndpoint.java:818)

at org.apache.coyote.AbstractProtocol.destroy(AbstractProtocol.java:532)

at org.apache.catalina.connector.Connector.destroyInternal(Connector.java:1023)

at org.apache.catalina.util.LifecycleBase.destroy(LifecycleBase.java:305)

at org.apache.catalina.core.StandardService.destroyInternal(StandardService.java:588)

at org.apache.catalina.util.LifecycleBase.destroy(LifecycleBase.java:305)

at org.apache.catalina.core.StandardServer.destroyInternal(StandardServer.java:859)

at org.apache.catalina.util.LifecycleBase.destroy(LifecycleBase.java:305)

at org.apache.catalina.startup.Catalina.start(Catalina.java:629)

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:351)

at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:485)

今天运行eclipse 运行tomcat启动不了，报如下错误，经查资料得知原来是web.xml出现了问题：

检查<url-pattern></url-pattern>中配置的内容是否缺少“/” ,"/"表示当前web应用。

如：<url-pattern>s/updata</url-pattern>错

应该为：<url-pattern>/s/updata</url-pattern>