web.xml配置servlet与servlet-mapping映射问题

配置好web.xml的servlet配置重新启动tomcat8的时候报错

控制台报错：

八月 10, 2018 1:53:21 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].StandardContext[/o2o]]
    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:945)
    at org.apache.catalina.core.StandardHost.startInternal(StandardHost.java:871)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:145)
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1410)
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1400)
    at java.util.concurrent.FutureTask.run(FutureTask.java:266)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at java.lang.Thread.run(Thread.java:745)
Caused by: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost].StandardContext[/o2o]]
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:162)
    ... 6 more
Caused by: java.lang.IllegalArgumentException: Servlet mapping specifies an unknown servlet name spring_dispatcher
    at org.apache.catalina.core.StandardContext.addServletMappingDecoded(StandardContext.java:3230)
    at org.apache.catalina.core.StandardContext.addServletMappingDecoded(StandardContext.java:3221)
    at org.apache.catalina.startup.ContextConfig.configureContext(ContextConfig.java:1375)
    at org.apache.catalina.startup.ContextConfig.webConfig(ContextConfig.java:1188)
    at org.apache.catalina.startup.ContextConfig.configureStart(ContextConfig.java:773)
    at org.apache.catalina.startup.ContextConfig.lifecycleEvent(ContextConfig.java:307)
    at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:95)
    at org.apache.catalina.util.LifecycleBase.fireLifecycleEvent(LifecycleBase.java:90)
    at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5262)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:145)
    ... 6 more

八月 10, 2018 1:53:21 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(FutureTask.java:122)
    at java.util.concurrent.FutureTask.get(FutureTask.java:192)
    at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:945)
    at org.apache.catalina.core.StandardEngine.startInternal(StandardEngine.java:262)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:145)
    at org.apache.catalina.core.StandardService.startInternal(StandardService.java:441)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:145)
    at org.apache.catalina.core.StandardServer.startInternal(StandardServer.java:789)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:145)
    at org.apache.catalina.startup.Catalina.start(Catalina.java:641)
    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:497)
    at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:349)
    at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:483)
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$StartChild.call(ContainerBase.java:1410)
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1400)
    at java.util.concurrent.FutureTask.run(FutureTask.java:266)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at java.lang.Thread.run(Thread.java:745)
Caused by: org.apache.catalina.LifecycleException: A child container failed during start
    at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:953)
    at org.apache.catalina.core.StandardHost.startInternal(StandardHost.java:871)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:145)
    ... 6 more

八月 10, 2018 1:53:21 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[8015]]
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:162)
    at org.apache.catalina.startup.Catalina.start(Catalina.java:641)
    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:497)
    at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:349)
    at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:483)
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:789)
    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:441)
    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:953)
    at org.apache.catalina.core.StandardEngine.startInternal(StandardEngine.java:262)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:145)
    ... 11 more

八月 10, 2018 1:53:21 下午 org.apache.coyote.AbstractProtocol pause
信息: Pausing ProtocolHandler ["http-nio-8090"]
八月 10, 2018 1:53:21 下午 org.apache.coyote.AbstractProtocol pause
信息: Pausing ProtocolHandler ["ajp-nio-8019"]
八月 10, 2018 1:53:21 下午 org.apache.catalina.core.StandardService stopInternal
信息: Stopping service Catalina
八月 10, 2018 1:53:21 下午 org.apache.coyote.AbstractProtocol destroy
信息: Destroying ProtocolHandler ["http-nio-8090"]
八月 10, 2018 1:53:21 下午 org.apache.coyote.AbstractProtocol destroy
严重: Failed to destroy end point associated with ProtocolHandler ["http-nio-8090"]
java.lang.NullPointerException
    at org.apache.tomcat.util.net.NioEndpoint.releaseCaches(NioEndpoint.java:315)
    at org.apache.tomcat.util.net.NioEndpoint.unbind(NioEndpoint.java:491)
    at org.apache.tomcat.util.net.AbstractEndpoint.destroy(AbstractEndpoint.java:896)
    at org.apache.coyote.AbstractProtocol.destroy(AbstractProtocol.java:551)
    at org.apache.catalina.connector.Connector.destroyInternal(Connector.java:1023)
    at org.apache.catalina.util.LifecycleBase.destroy(LifecycleBase.java:292)
    at org.apache.catalina.core.StandardService.destroyInternal(StandardService.java:589)
    at org.apache.catalina.util.LifecycleBase.destroy(LifecycleBase.java:292)
    at org.apache.catalina.core.StandardServer.destroyInternal(StandardServer.java:879)
    at org.apache.catalina.util.LifecycleBase.destroy(LifecycleBase.java:292)
    at org.apache.catalina.startup.Catalina.start(Catalina.java:645)
    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:497)
    at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:349)
    at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:483)

八月 10, 2018 1:53:21 下午 org.apache.coyote.AbstractProtocol destroy
信息: Destroying ProtocolHandler ["ajp-nio-8019"]
八月 10, 2018 1:53:21 下午 org.apache.coyote.AbstractProtocol destroy
严重: Failed to destroy end point associated with ProtocolHandler ["ajp-nio-8019"]
java.lang.NullPointerException
    at org.apache.tomcat.util.net.NioEndpoint.releaseCaches(NioEndpoint.java:315)
    at org.apache.tomcat.util.net.NioEndpoint.unbind(NioEndpoint.java:491)
    at org.apache.tomcat.util.net.AbstractEndpoint.destroy(AbstractEndpoint.java:896)
    at org.apache.coyote.AbstractProtocol.destroy(AbstractProtocol.java:551)
    at org.apache.catalina.connector.Connector.destroyInternal(Connector.java:1023)
    at org.apache.catalina.util.LifecycleBase.destroy(LifecycleBase.java:292)
    at org.apache.catalina.core.StandardService.destroyInternal(StandardService.java:589)
    at org.apache.catalina.util.LifecycleBase.destroy(LifecycleBase.java:292)
    at org.apache.catalina.core.StandardServer.destroyInternal(StandardServer.java:879)
    at org.apache.catalina.util.LifecycleBase.destroy(LifecycleBase.java:292)
    at org.apache.catalina.startup.Catalina.start(Catalina.java:645)
    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:497)
    at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:349)
    at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:483)

出错原因：

 java.lang.IllegalArgumentException: Servlet mapping specifies an unknown servlet name spring_dispatcher

servlet与servlet-mapping不匹配 （name）

返回web.xml文件查看

servlet中的name是spring-dispatcher

servlet-mapping中的name是spring_dispatcher

即map映射没有匹配成功

修改后，成功启动，问题解决。