SpringBoot运行异常：

java.lang.NoSuchMethodError: javax.servlet.http.HttpServletRequest.getHttpServletMapping()Ljavax/servlet/http/HttpServletMapping;

at org.apache.catalina.core.ApplicationHttpRequest.setRequest(ApplicationHttpRequest.java:690) ~[tomcat-embed-core-9.0.16.jar:9.0.16]
at org.apache.catalina.core.ApplicationHttpRequest.(ApplicationHttpRequest.java:114) ~[tomcat-embed-core-9.0.16.jar:9.0.16]
at org.apache.catalina.core.ApplicationDispatcher.wrapRequest(ApplicationDispatcher.java:917) ~[tomcat-embed-core-9.0.16.jar:9.0.16]
at org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:358) ~[tomcat-embed-core-9.0.16.jar:9.0.16]
at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:312) ~[tomcat-embed-core-9.0.16.jar:9.0.16]
at org.apache.catalina.core.StandardHostValve.custom(StandardHostValve.java:394) [tomcat-embed-core-9.0.16.jar:9.0.16]
at org.apache.catalina.core.StandardHostValve.status(StandardHostValve.java:253) [tomcat-embed-core-9.0.16.jar:9.0.16]
at org.apache.catalina.core.StandardHostValve.throwable(StandardHostValve.java:348) [tomcat-embed-core-9.0.16.jar:9.0.16]
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:173) [tomcat-embed-core-9.0.16.jar:9.0.16]
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92) [tomcat-embed-core-9.0.16.jar:9.0.16]
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74) [tomcat-embed-core-9.0.16.jar:9.0.16]
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343) [tomcat-embed-core-9.0.16.jar:9.0.16]
at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:408) [tomcat-embed-core-9.0.16.jar:9.0.16]
at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66) [tomcat-embed-core-9.0.16.jar:9.0.16]
at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:834) [tomcat-embed-core-9.0.16.jar:9.0.16]
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1415) [tomcat-embed-core-9.0.16.jar:9.0.16]
at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) [tomcat-embed-core-9.0.16.jar:9.0.16]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [na:1.8.0_172]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [na:1.8.0_172]
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-embed-core-9.0.16.jar:9.0.16]
at java.lang.Thread.run(Thread.java:748) [na:1.8.0_172]

分析：

springboot项目，Tomcat是内置错误，我项目里压根就没这个jar包啊，不可能是jdk里面的这个jar包和springboot内置的servlet-apijar包冲突

解决方案：

进到jdk目录下的jdk1.8.0_251\jre\lib\ext，把里面的servlet-api这个jar包删除
（java正在运行，直接删除肯定是不行的，可以用360的强制删除或者关掉idea），就可以了。

删除之前一定要做好文件备份。