在IDEA的tomcat中启动web项目报错：org.apache.tomcat.util.modeler.BaseModelMBean.invoke 调用方法[manageApp]时发生异常

部分错误信息：

[2021-01-25 06:03:15,297] Artifact maven_web_test02:war exploded: Artifact is being deployed, please wait...
25-Jan-2021 18:03:15.691 严重 [RMI TCP Connection(3)-127.0.0.1] org.apache.tomcat.util.modeler.BaseModelMBean.invoke 调用方法[manageApp]时发生异常
	java.lang.IllegalStateException: 启动子级时出错
		at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:720)
		at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:690)
		at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:705)
		at org.apache.catalina.startup.HostConfig.manageApp(HostConfig.java:1727)
		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:288)
		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:456)
		at org.apache.catalina.mbeans.MBeanFactory.createStandardContext(MBeanFactory.java:405)
		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:288)
		at com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.invoke(DefaultMBeanServerInterceptor.java:819)
		at com.sun.jmx.mbeanserver.JmxMBeanServer.invoke(JmxMBeanServer.java:801)
		at com.sun.jmx.remote.security.MBeanServerAccessController.invoke(MBeanServerAccessController.java:468)
		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 java.security.AccessController.doPrivileged(Native Method)
		at javax.management.remote.rmi.RMIConnectionImpl.doPrivilegedOperation(RMIConnectionImpl.java:1408)
		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:357)
		at sun.rmi.transport.Transport$1.run(Transport.java:200)
		at sun.rmi.transport.Transport$1.run(Transport.java:197)
		at java.security.AccessController.doPrivileged(Native Method)
		at sun.rmi.transport.Transport.serviceCall(Transport.java:196)
		at sun.rmi.transport.tcp.TCPTransport.handleMessages(TCPTransport.java:573)
		at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run0(TCPTransport.java:834)
		at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.lambda$run$0(TCPTransport.java:688)
		at java.security.AccessController.doPrivileged(Native Method)
		at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run(TCPTransport.java:687)
		at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
		at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
		at java.lang.Thread.run(Thread.java:748)
	Caused by: org.apache.catalina.LifecycleException: 无法启动组件[StandardEngine[Catalina].StandardHost[localhost].StandardContext[/maven]]
		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.addChildInternal(ContainerBase.java:717)
		... 43 more
	Caused by: java.lang.IllegalArgumentException: servlet映射中的<url pattern>[app]无效
		at org.apache.catalina.core.StandardContext.addServletMappingDecoded(StandardContext.java:3176)
		at org.apache.catalina.Context.addServletMappingDecoded(Context.java:881)
		at org.apache.catalina.startup.ContextConfig.configureContext(ContextConfig.java:1603)
		at org.apache.catalina.startup.ContextConfig.webConfig(ContextConfig.java:1377)
		at org.apache.catalina.startup.ContextConfig.configureStart(ContextConfig.java:983)
		at org.apache.catalina.startup.ContextConfig.lifecycleEvent(ContextConfig.java:302)
		at org.apache.catalina.util.LifecycleBase.fireLifecycleEvent(LifecycleBase.java:123)
		at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5044)
		at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
		... 44 more

注意最下面的 Caused by 也就是它给出的原因：

出错原因：web.xml文件中配置的servlet映射地址无效

servlet的映射地址必须以 “/” 开头，正确格式为：