Caused by: java.lang.ClassCastException: class org.springframework.boot.web.embedded.undertow.UndertowServletWebServerFactory cannot be cast to class org.springframework.boot.web.embedded.tomcat.TomcatServletWebServerFactory (org.springframework.boot.web.embedded.undertow.UndertowServletWebServerFactory and org.springframework.boot.web.embedded.tomcat.TomcatServletWebServerFactory are in unnamed module of loader 'app') at org.springframework.boot.web.server.WebServerFactoryCustomizerBeanPostProcessor.lambda$postProcessBeforeInitialization$0(WebServerFactoryCustomizerBeanPostProcessor.java:78) at org.springframework.boot.util.LambdaSafe$Callbacks.lambda$null$0(LambdaSafe.java:291) at org.springframework.boot.util.LambdaSafe$LambdaSafeCallback.invoke(LambdaSafe.java:162) at org.springframework.boot.util.LambdaSafe$Callbacks.lambda$invoke$1(LambdaSafe.java:290) at java.base/java.util.ArrayList.forEach(ArrayList.java:1541) at java.base/java.util.Collections$UnmodifiableCollection.forEach(Collections.java:1085) at org.springframework.boot.util.LambdaSafe$Callbacks.invoke(LambdaSafe.java:289) at org.springframework.boot.web.server.WebServerFactoryCustomizerBeanPostProcessor.postProcessBeforeInitialization(WebServerFactoryCustomizerBeanPostProcessor.java:78) at org.springframework.boot.web.server.WebServerFactoryCustomizerBeanPostProcessor.postProcessBeforeInitialization(WebServerFactoryCustomizerBeanPostProcessor.java:61) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.applyBeanPostProcessorsBeforeInitialization(AbstractAutowireCapableBeanFactory.java:416) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1686) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:573) ... 16 more

启动的时候报错，报错内容如上
问题原因：
1.你本地JDK冲突，也许工程是低版本JDK，你电脑环境变量配置了高版本的
2.你jar冲突
3.你工程配置有问题，看下JDK配置和工程配置检查下