IDEA启动Tomcat，报“LifecycleException: Failed to start component [StandardEngine[Catalina]

        IDEA启动Tomcat，报“LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost].StandardContext[]]”问题。

        1、 IDEA启动Tomcat，报下面的错误：

org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost].StandardContext[]]
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:158)
at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:724)
at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:700)
at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:734)
at org.apache.catalina.startup.HostConfig.manageApp(HostConfig.java:1702)
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.tomcat.util.modeler.BaseModelMBean.invoke(BaseModelMBean.java:300)
at com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.invoke(DefaultMBeanServerInterceptor.java:819)
at com.sun.jmx.mbeanserver.JmxMBeanServer.invoke(JmxMBeanServer.java:801)
at org.apache.catalina.mbeans.MBeanFactory.createStandardContext(MBeanFactory.java:482)
at org.apache.catalina.mbeans.MBeanFactory.createStandardContext(MBeanFactory.java:431)
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.tomcat.util.modeler.BaseModelMBean.invoke(BaseModelMBean.java:300)
at com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.invoke(DefaultMBeanServerInterceptor.java:819)
at com.sun.jmx.mbeanserver.JmxMBeanServer.invoke(JmxMBeanServer.java:801)
at javax.management.remote.rmi.RMIConnectionImpl.doOperation(RMIConnectionImpl.java:1468)
at javax.management.remote.rmi.RMIConnectionImpl.access$300(RMIConnectionImpl.java:76)
at javax.management.remote.rmi.RMIConnectionImpl$PrivilegedOperation.run(RMIConnectionImpl.java:1309)
at javax.management.remote.rmi.RMIConnectionImpl.doPrivilegedOperation(RMIConnectionImpl.java:1401)
at javax.management.remote.rmi.RMIConnectionImpl.invoke(RMIConnectionImpl.java:829)
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 sun.rmi.server.UnicastServerRef.dispatch(UnicastServerRef.java:323)
at sun.rmi.transport.Transport$1.run(Transport.java:200)
at sun.rmi.transport.Transport$1.run(Transport.java:197)
at java.security.AccessController.doPrivileged(Native Method)
at sun.rmi.transport.Transport.serviceCall(Transport.java:196)
at sun.rmi.transport.tcp.TCPTransport.handleMessages(TCPTransport.java:568)
at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run0(TCPTransport.java:826)
at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.lambda$run$0(TCPTransport.java:683)
at java.security.AccessController.doPrivileged(Native Method)
at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run(TCPTransport.java:682)
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: java.lang.IllegalArgumentException: Invalid <url-pattern> firstServlet.do in servlet mapping
at org.apache.catalina.core.StandardContext.addServletMapping(StandardContext.java:3128)
at org.apache.catalina.core.StandardContext.addServletMapping(StandardContext.java:3103)
at org.apache.catalina.startup.ContextConfig.configureContext(ContextConfig.java:1367)
at org.apache.catalina.startup.ContextConfig.webConfig(ContextConfig.java:1181)
at org.apache.catalina.startup.ContextConfig.configureStart(ContextConfig.java:771)
at org.apache.catalina.startup.ContextConfig.lifecycleEvent(ContextConfig.java:298)
at org.apache.catalina.util.LifecycleBase.fireLifecycleEvent(LifecycleBase.java:94)
at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5076)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:152)


        2、解决方案：发现是web.xml配置“servlet-mapping”的“url-pattern”少了斜杠；增加斜杠即可。