运行项目时报错，求指导

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[/test]]
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:147)
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[/test]]
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:153)
… 6 more
Caused by: java.lang.IllegalArgumentException: The servlets named [com.tst.a] and [com.tst.t.A] are both mapped to the url-pattern [/a] which is not permitted
at org.apache.catalina.deploy.WebXml.addServletMapping(WebXml.java:293)
at org.apache.catalina.startup.ContextConfig.processAnnotationWebServlet(ContextConfig.java:2460)
at org.apache.catalina.startup.ContextConfig.processAnnotationsStream(ContextConfig.java:2135)
at org.apache.catalina.startup.ContextConfig.processAnnotationsFile(ContextConfig.java:2096)
at org.apache.catalina.startup.ContextConfig.processAnnotationsFile(ContextConfig.java:2088)
at org.apache.catalina.startup.ContextConfig.processAnnotationsFile(ContextConfig.java:2088)
at org.apache.catalina.startup.ContextConfig.processAnnotationsFile(ContextConfig.java:2088)
at org.apache.catalina.startup.ContextConfig.webConfig(ContextConfig.java:1302)
at org.apache.catalina.startup.ContextConfig.configureStart(ContextConfig.java:887)
at org.apache.catalina.startup.ContextConfig.lifecycleEvent(ContextConfig.java:387)
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:5503)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:147)
… 6 more
十月 09, 2016 10:37:44 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:147)
at org.apache.catalina.core.StandardService.startInternal(StandardService.java:444)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:147)
at org.apache.catalina.core.StandardServer.startInternal(StandardServer.java:756)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:147)
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:153)
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:147)
… 6 more
十月 09, 2016 10:37:44 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:153)
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:153)
at org.apache.catalina.core.StandardServer.startInternal(StandardServer.java:756)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:147)
… 7 more
Caused by: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina]]
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:153)
at org.apache.catalina.core.StandardService.startInternal(StandardService.java:444)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:147)
… 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:147)
… 11 more
十月 09, 2016 10:37:44 下午 org.apache.coyote.AbstractProtocol pause
信息: Pausing ProtocolHandler [“http-bio-8080”]
十月 09, 2016 10:37:44 下午 org.apache.coyote.AbstractProtocol pause
信息: Pausing ProtocolHandler [“ajp-bio-8009”]
十月 09, 2016 10:37:44 下午 org.apache.catalina.core.StandardService stopInternal
信息: Stopping service Catalina
十月 09, 2016 10:37:44 下午 org.apache.coyote.AbstractProtocol destroy
信息: Destroying ProtocolHandler [“http-bio-8080”]
十月 09, 2016 10:37:44 下午 org.apache.coyote.AbstractProtocol destroy
信息: Destroying ProtocolHandler [“ajp-bio-8009”]