使用Maven,idea建立web專案啟動不了,war exploded: Artifact is being deployed, please wait...

頁面報錯輸出如下：

[2020-11-01 11:08:13,862] Artifact ch03-maven-web:war exploded: Artifact is being deployed, please wait...
01-Nov-2020 11:08:14.018 涓ラ噸 [RMI TCP Connection(9)-127.0.0.1] org.apache.catalina.core.ContainerBase.addChildInternal ContainerBase.addChild: start: 
	org.apache.catalina.LifecycleException: 鏃犳硶鍚姩緇勪歡[StandardEngine[Catalina].StandardHost[localhost].StandardContext[/ch03_maven_web]]
		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:743)
		at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:719)
		at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:705)
		at org.apache.catalina.startup.HostConfig.manageApp(HostConfig.java:1719)
		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:286)
		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:479)
		at org.apache.catalina.mbeans.MBeanFactory.createStandardContext(MBeanFactory.java:428)
		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:286)
		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: java.lang.IllegalArgumentException: servlet鏄犲皠涓殑<url pattern>[hello]鏃犳晥
		at org.apache.catalina.core.StandardContext.addServletMappingDecoded(StandardContext.java:3173)
		at org.apache.catalina.core.StandardContext.addServletMappingDecoded(StandardContext.java:3160)
		at org.apache.catalina.startup.ContextConfig.configureContext(ContextConfig.java:1389)
		at org.apache.catalina.startup.ContextConfig.webConfig(ContextConfig.java:1166)
		at org.apache.catalina.startup.ContextConfig.configureStart(ContextConfig.java:779)
		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:5053)
		at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
		... 44 more
01-Nov-2020 11:08:14.030 涓ラ噸 [RMI TCP Connection(9)-127.0.0.1] org.apache.tomcat.util.modeler.BaseModelMBean.invoke Exception invoking method manageApp
	java.lang.IllegalStateException: ContainerBase.addChild: start: org.apache.catalina.LifecycleException: 鏃犳硶鍚姩緇勪歡[StandardEngine[Catalina].StandardHost[localhost].StandardContext[/ch03_maven_web]]
[2020-11-01 11:08:14,072] Artifact ch03-maven-web:war exploded: Error during artifact deployment. See server log for details.

找了下解決辦法，原來是在web.xml裡面的<url-pattern>hello</url-pattern>hello前面沒有加/。