在Java web中碰到一个问题，具体是启动tomcat服务器失败：

Server Tomcat v9.0 Server at localhost failed to start.
具体的错误信息如下：
严重: 子容器启动失败
java.util.concurrent.ExecutionException: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost].StandardContext[/Demo1]]
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:916)
at org.apache.catalina.core.StandardHost.startInternal(StandardHost.java:841)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
at org.apache.catalina.core.ContainerBase $StartChild.call(ContainerBase.java:1384) at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1374)
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:909)
at org.apache.catalina.core.StandardEngine.startInternal(StandardEngine.java:262)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
at org.apache.catalina.core.StandardService.startInternal(StandardService.java:421)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
at org.apache.catalina.core.StandardServer.startInternal(StandardServer.java:932)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
at org.apache.catalina.startup.Catalina.start(Catalina.java:633)
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:344)
at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:475)
Caused by: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost].StandardContext[/Demo1]]
at org.apache.catalina.util.LifecycleBase.handleSubClassException(LifecycleBase.java:440)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:198)
at org.apache.catalina.core.ContainerBase $StartChild.call(ContainerBase.java:1384) at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1374)
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:909)
… 21 more
Caused by: java.lang.IllegalArgumentException: 名为 [RegistServlet]和 [com.web.servlet.RegistServlet] 的servlet不能映射为一个url模式(url-pattern) [/RegistServlet]
at org.apache.tomcat.util.descriptor.web.WebXml.addServletMappingDecoded(WebXml.java:342)
at org.apache.tomcat.util.descriptor.web.WebXml.addServletMapping(WebXml.java:335)
at org.apache.catalina.startup.ContextConfig.processAnnotationWebServlet(ContextConfig.java:2460)
at org.apache.catalina.startup.ContextConfig.processClass(ContextConfig.java:2136)
at org.apache.catalina.startup.ContextConfig.processAnnotationsStream(ContextConfig.java:2125)
at org.apache.catalina.startup.ContextConfig.processAnnotationsWebResource(ContextConfig.java:2017)
at org.apache.catalina.startup.ContextConfig.processAnnotationsWebResource(ContextConfig.java:2011)
at org.apache.catalina.startup.ContextConfig.processAnnotationsWebResource(ContextConfig.java:2011)
at org.apache.catalina.startup.ContextConfig.processAnnotationsWebResource(ContextConfig.java:2011)
at org.apache.catalina.startup.ContextConfig.processClasses(ContextConfig.java:1234)
at org.apache.catalina.startup.ContextConfig.webConfig(ContextConfig.java:1143)
at org.apache.catalina.startup.ContextConfig.configureStart(ContextConfig.java:775)
at org.apache.catalina.startup.ContextConfig.lifecycleEvent(ContextConfig.java:301)
at org.apache.catalina.util.LifecycleBase.fireLifecycleEvent(LifecycleBase.java:123)
at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5051)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
… 27 more

九月 22, 2019 4:29:11 下午 org.apache.catalina.core.ContainerBase startInternal
严重: 子容器启动失败
java.util.concurrent.ExecutionException: org.apache.catalina.LifecycleException: 子容器启动失败
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:916)
at org.apache.catalina.core.StandardEngine.startInternal(StandardEngine.java:262)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
at org.apache.catalina.core.StandardService.startInternal(StandardService.java:421)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
at org.apache.catalina.core.StandardServer.startInternal(StandardServer.java:932)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
at org.apache.catalina.startup.Catalina.start(Catalina.java:633)
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:344)
at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:475)
Caused by: org.apache.catalina.LifecycleException: 子容器启动失败
at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:928)
at org.apache.catalina.core.StandardHost.startInternal(StandardHost.java:841)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
at org.apache.catalina.core.ContainerBase $StartChild.call(ContainerBase.java:1384) at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1374)
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:909)
… 13 more
Caused by: java.util.concurrent.ExecutionException: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost].StandardContext[/Demo1]]
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:916)
… 21 more
Caused by: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost].StandardContext[/Demo1]]
at org.apache.catalina.util.LifecycleBase.handleSubClassException(LifecycleBase.java:440)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:198)
at org.apache.catalina.core.ContainerBase $StartChild.call(ContainerBase.java:1384) at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1374)
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:909)
… 21 more
Caused by: java.lang.IllegalArgumentException: 名为 [RegistServlet]和 [com.web.servlet.RegistServlet] 的servlet不能映射为一个url模式(url-pattern) [/RegistServlet]
at org.apache.tomcat.util.descriptor.web.WebXml.addServletMappingDecoded(WebXml.java:342)
at org.apache.tomcat.util.descriptor.web.WebXml.addServletMapping(WebXml.java:335)
at org.apache.catalina.startup.ContextConfig.processAnnotationWebServlet(ContextConfig.java:2460)
at org.apache.catalina.startup.ContextConfig.processClass(ContextConfig.java:2136)
at org.apache.catalina.startup.ContextConfig.processAnnotationsStream(ContextConfig.java:2125)
at org.apache.catalina.startup.ContextConfig.processAnnotationsWebResource(ContextConfig.java:2017)
at org.apache.catalina.startup.ContextConfig.processAnnotationsWebResource(ContextConfig.java:2011)
at org.apache.catalina.startup.ContextConfig.processAnnotationsWebResource(ContextConfig.java:2011)
at org.apache.catalina.startup.ContextConfig.processAnnotationsWebResource(ContextConfig.java:2011)
at org.apache.catalina.startup.ContextConfig.processClasses(ContextConfig.java:1234)
at org.apache.catalina.startup.ContextConfig.webConfig(ContextConfig.java:1143)
at org.apache.catalina.startup.ContextConfig.configureStart(ContextConfig.java:775)
at org.apache.catalina.startup.ContextConfig.lifecycleEvent(ContextConfig.java:301)
at org.apache.catalina.util.LifecycleBase.fireLifecycleEvent(LifecycleBase.java:123)
at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5051)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
… 27 more

九月 22, 2019 4:29:11 下午 org.apache.catalina.startup.Catalina start
严重: 所必需的服务组件启动失败，所以无法启动Tomcat
org.apache.catalina.LifecycleException: 子容器启动失败
at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:928)
at org.apache.catalina.core.StandardEngine.startInternal(StandardEngine.java:262)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
at org.apache.catalina.core.StandardService.startInternal(StandardService.java:421)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
at org.apache.catalina.core.StandardServer.startInternal(StandardServer.java:932)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
at org.apache.catalina.startup.Catalina.start(Catalina.java:633)
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:344)
at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:475)
Caused by: java.util.concurrent.ExecutionException: org.apache.catalina.LifecycleException: 子容器启动失败
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:916)
… 13 more
Caused by: org.apache.catalina.LifecycleException: 子容器启动失败
at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:928)
at org.apache.catalina.core.StandardHost.startInternal(StandardHost.java:841)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
at org.apache.catalina.core.ContainerBase $StartChild.call(ContainerBase.java:1384) at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1374)
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:909)
… 13 more
Caused by: java.util.concurrent.ExecutionException: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost].StandardContext[/Demo1]]
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:916)
… 21 more
Caused by: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost].StandardContext[/Demo1]]
at org.apache.catalina.util.LifecycleBase.handleSubClassException(LifecycleBase.java:440)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:198)
at org.apache.catalina.core.ContainerBase $StartChild.call(ContainerBase.java:1384) at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1374)
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:909)
… 21 more
Caused by: java.lang.IllegalArgumentException: 名为 [RegistServlet]和 [com.web.servlet.RegistServlet] 的servlet不能映射为一个url模式(url-pattern) [/RegistServlet]
at org.apache.tomcat.util.descriptor.web.WebXml.addServletMappingDecoded(WebXml.java:342)
at org.apache.tomcat.util.descriptor.web.WebXml.addServletMapping(WebXml.java:335)
at org.apache.catalina.startup.ContextConfig.processAnnotationWebServlet(ContextConfig.java:2460)
at org.apache.catalina.startup.ContextConfig.processClass(ContextConfig.java:2136)
at org.apache.catalina.startup.ContextConfig.processAnnotationsStream(ContextConfig.java:2125)
at org.apache.catalina.startup.ContextConfig.processAnnotationsWebResource(ContextConfig.java:2017)
at org.apache.catalina.startup.ContextConfig.processAnnotationsWebResource(ContextConfig.java:2011)
at org.apache.catalina.startup.ContextConfig.processAnnotationsWebResource(ContextConfig.java:2011)
at org.apache.catalina.startup.ContextConfig.processAnnotationsWebResource(ContextConfig.java:2011)
at org.apache.catalina.startup.ContextConfig.processClasses(ContextConfig.java:1234)
at org.apache.catalina.startup.ContextConfig.webConfig(ContextConfig.java:1143)
at org.apache.catalina.startup.ContextConfig.configureStart(ContextConfig.java:775)
at org.apache.catalina.startup.ContextConfig.lifecycleEvent(ContextConfig.java:301)
at org.apache.catalina.util.LifecycleBase.fireLifecycleEvent(LifecycleBase.java:123)
at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5051)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
… 27 more

***其中在CauseBy中有[com.web.servlet.RegistServlet] 的servlet不能映射为一个url模式(url-pattern) ***
检查下web.xml文件，个人觉得可能项目中的web.xml里的Regist 和 类包里的Regist 同时匹配，所以后面我更改了我的web.xml，改了其url-pattern就解决问题了。