1. 这就是tomcat无法打开出现的界面
这个时候就要检查一下console里面输出的错误信息，我们只需要关注
Caused by就行
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[/firstServlet]]
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:951)
at org.apache.catalina.core.StandardHost.startInternal(StandardHost.java:831)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1432)
at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1422)
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:944)
at org.apache.catalina.core.StandardEngine.startInternal(StandardEngine.java:261)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
at org.apache.catalina.core.StandardService.startInternal(StandardService.java:422)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
at org.apache.catalina.core.StandardServer.startInternal(StandardServer.java:801)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
at org.apache.catalina.startup.Catalina.start(Catalina.java:695)
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:350)
at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:492)
Caused by: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost].StandardContext[/firstServlet]]
at org.apache.catalina.util.LifecycleBase.handleSubClassException(LifecycleBase.java:441)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:198)
at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1432)
at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1422)
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:944)
... 21 more
Caused by: java.lang.IllegalArgumentException: Invalid <url-pattern> [testSession] in servlet mapping
at org.apache.catalina.core.StandardContext.addServletMappingDecoded(StandardContext.java:3136)
at org.apache.catalina.Context.addServletMappingDecoded(Context.java:879)
at org.apache.catalina.startup.ContextConfig.configureContext(ContextConfig.java:1380)
at org.apache.catalina.startup.ContextConfig.webConfig(ContextConfig.java:1191)
at org.apache.catalina.startup.ContextConfig.configureStart(ContextConfig.java:769)
at org.apache.catalina.startup.ContextConfig.lifecycleEvent(ContextConfig.java:299)
at org.apache.catalina.util.LifecycleBase.fireLifecycleEvent(LifecycleBase.java:123)
at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5007)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
... 27 more
十一月 20, 2018 9:27:44 下午 org.apache.catalina.core.ContainerBase startInternal
严重: A child container failed during start
java.util.concurrent.ExecutionException: org.apache.catalina.LifecycleException: A child container failed during start
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:951)
at org.apache.catalina.core.StandardEngine.startInternal(StandardEngine.java:261)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
at org.apache.catalina.core.StandardService.startInternal(StandardService.java:422)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
at org.apache.catalina.core.StandardServer.startInternal(StandardServer.java:801)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
at org.apache.catalina.startup.Catalina.start(Catalina.java:695)
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:350)
at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:492)
Caused by: org.apache.catalina.LifecycleException: A child container failed during start
at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:963)
at org.apache.catalina.core.StandardHost.startInternal(StandardHost.java:831)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1432)
at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1422)
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:944)
... 13 more
Caused by: java.util.concurrent.ExecutionException: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost].StandardContext[/firstServlet]]
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:951)
... 21 more
Caused by: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost].StandardContext[/firstServlet]]
at org.apache.catalina.util.LifecycleBase.handleSubClassException(LifecycleBase.java:441)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:198)
at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1432)
at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1422)
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:944)
... 21 more
Caused by: java.lang.IllegalArgumentException: Invalid <url-pattern> [testSession] in servlet mapping
at org.apache.catalina.core.StandardContext.addServletMappingDecoded(StandardContext.java:3136)
at org.apache.catalina.Context.addServletMappingDecoded(Context.java:879)
at org.apache.catalina.startup.ContextConfig.configureContext(ContextConfig.java:1380)
at org.apache.catalina.startup.ContextConfig.webConfig(ContextConfig.java:1191)
at org.apache.catalina.startup.ContextConfig.configureStart(ContextConfig.java:769)
at org.apache.catalina.startup.ContextConfig.lifecycleEvent(ContextConfig.java:299)
at org.apache.catalina.util.LifecycleBase.fireLifecycleEvent(LifecycleBase.java:123)
at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5007)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
... 27 more
十一月 20, 2018 9:27:44 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: A child container failed during start
at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:963)
at org.apache.catalina.core.StandardEngine.startInternal(StandardEngine.java:261)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
at org.apache.catalina.core.StandardService.startInternal(StandardService.java:422)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
at org.apache.catalina.core.StandardServer.startInternal(StandardServer.java:801)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
at org.apache.catalina.startup.Catalina.start(Catalina.java:695)
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:350)
at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:492)
Caused by: java.util.concurrent.ExecutionException: org.apache.catalina.LifecycleException: A child container failed during start
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:951)
... 13 more
Caused by: org.apache.catalina.LifecycleException: A child container failed during start
at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:963)
at org.apache.catalina.core.StandardHost.startInternal(StandardHost.java:831)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1432)
at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1422)
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:944)
... 13 more
Caused by: java.util.concurrent.ExecutionException: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost].StandardContext[/firstServlet]]
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:951)
... 21 more
Caused by: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost].StandardContext[/firstServlet]]
at org.apache.catalina.util.LifecycleBase.handleSubClassException(LifecycleBase.java:441)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:198)
at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1432)
at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1422)
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:944)
... 21 more
Caused by: java.lang.IllegalArgumentException: Invalid <url-pattern> [testSession] in servlet mapping
at org.apache.catalina.core.StandardContext.addServletMappingDecoded(StandardContext.java:3136)
at org.apache.catalina.Context.addServletMappingDecoded(Context.java:879)
at org.apache.catalina.startup.ContextConfig.configureContext(ContextConfig.java:1380)
at org.apache.catalina.startup.ContextConfig.webConfig(ContextConfig.java:1191)
at org.apache.catalina.startup.ContextConfig.configureStart(ContextConfig.java:769)
at org.apache.catalina.startup.ContextConfig.lifecycleEvent(ContextConfig.java:299)
at org.apache.catalina.util.LifecycleBase.fireLifecycleEvent(LifecycleBase.java:123)
at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5007)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
... 27 more
这里面代码太多了，我们要找到重点Caused by，
Caused by: java.lang.IllegalArgumentException: Invalid <url-pattern> [testSession] in servlet mapping
at org.apache.catalina.core.StandardContext.addServletMappingDecoded(StandardContext.java:3136)
at org.apache.catalina.Context.addServletMappingDecoded(Context.java:879)
at org.apache.catalina.startup.ContextConfig.configureContext(ContextConfig.java:1380)
at org.apache.catalina.startup.ContextConfig.webConfig(ContextConfig.java:1191)
at org.apache.catalina.startup.ContextConfig.configureStart(ContextConfig.java:769)
at org.apache.catalina.startup.ContextConfig.lifecycleEvent(ContextConfig.java:299)
at org.apache.catalina.util.LifecycleBase.fireLifecycleEvent(LifecycleBase.java:123)
at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5007)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
... 27 more
找到这个，发现是原来修改的web.xml里面的
用来描述匹配的出现了语法错误，在testSession前面加上"/"反斜杠即可。
注意，如果你在其它的package里面，想要启动tomcat，如果这个web.xml没有配置好，这个地方会影响别的地方