报错内容如下图：
org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost].StandardContext[/saas_notice_server_war_exploded]]
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:162)
at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:1015)
at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:991)
at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:652)
at org.apache.catalina.startup.HostConfig.manageApp(HostConfig.java:1899)
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:483)
at org.apache.tomcat.util.modeler.BaseModelMBean.invoke(BaseModelMBean.java:301)
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:618)
at org.apache.catalina.mbeans.MBeanFactory.createStandardContext(MBeanFactory.java:565)
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:483)
at org.apache.tomcat.util.modeler.BaseModelMBean.invoke(BaseModelMBean.java:301)
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:1466)
at javax.management.remote.rmi.RMIConnectionImpl.access$300(RMIConnectionImpl.java:76)
at javax.management.remote.rmi.RMIConnectionImpl$PrivilegedOperation.run(RMIConnectionImpl.java:1307)
at java.security.AccessController.doPrivileged(Native Method)
at javax.management.remote.rmi.RMIConnectionImpl.doPrivilegedOperation(RMIConnectionImpl.java:1406)
at javax.management.remote.rmi.RMIConnectionImpl.invoke(RMIConnectionImpl.java:828)
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:483)
at sun.rmi.server.UnicastServerRef.dispatch(UnicastServerRef.java:323)
at sun.rmi.transport.Transport$1.run(Transport.java:178)
at sun.rmi.transport.Transport$1.run(Transport.java:175)
at java.security.AccessController.doPrivileged(Native Method)
at sun.rmi.transport.Transport.serviceCall(Transport.java:174)
at sun.rmi.transport.tcp.TCPTransport.handleMessages(TCPTransport.java:557)
at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run0(TCPTransport.java:812)
at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run(TCPTransport.java:671)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745)
Caused by: java.lang.NoClassDefFoundError: javax/servlet/GenericFilter
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClass(ClassLoader.java:760)
at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
at org.apache.catalina.loader.WebappClassLoaderBase.findClassInternal(WebappClassLoaderBase.java:3205)
at org.apache.catalina.loader.WebappClassLoaderBase.findClass(WebappClassLoaderBase.java:1373)
at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1861)
at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1735)
at org.apache.tomcat.websocket.server.WsServerContainer.<init>(WsServerContainer.java:106)
at org.apache.tomcat.websocket.server.WsSci.init(WsSci.java:137)
at org.apache.tomcat.websocket.server.WsSci.onStartup(WsSci.java:49)
at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5622)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:145)
... 42 more
Caused by: java.lang.ClassNotFoundException: javax.servlet.GenericFilter
at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1892)
at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1735)
... 54 more报错截图
项目是springboot，使用内置的tomcat是可以本地启动的。现在需要使用外置tomcat，将项目打包成war启动。 idea使用tomcat启动，百度了好久，没找到问题。后面想了一下有没有可能是tomcat版本的问题。我用的是 apache-tomcat-7.0.82 ，看了一下springboot内置的tomcat发现已经使用到了apache-tomcat-9.0.68。
后面换了apache-tomcat-9.0.68之后，就成功启动了。
附上tomcat-9 下载地址
https://tomcat.apache.org/download-90.cgi
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