Caused by: java.lang.ClassNotFoundException: javax.servlet.ServletRegistration$Dynamic

在使用servlet-api时报如下错误：

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'statViewServletRegistrationBean' defined in class path resource [com/alibaba/druid/spring/boot/autoconfigure/stat/DruidStatViewServletConfiguration.class]: Post-processing of merged bean definition failed; nested exception is java.lang.IllegalStateException: Failed to introspect Class [org.springframework.boot.web.servlet.ServletRegistrationBean] from ClassLoader [sun.misc.Launcher$AppClassLoader@18b4aac2]
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:570) ~[spring-beans-5.1.8.RELEASE.jar:5.1.8.RELEASE]
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:515) ~[spring-beans-5.1.8.RELEASE.jar:5.1.8.RELEASE]
	at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:320) ~[spring-beans-5.1.8.RELEASE.jar:5.1.8.RELEASE]
	at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222) ~[spring-beans-5.1.8.RELEASE.jar:5.1.8.RELEASE]
	at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:318) ~[spring-beans-5.1.8.RELEASE.jar:5.1.8.RELEASE]
	at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:199) ~[spring-beans-5.1.8.RELEASE.jar:5.1.8.RELEASE]
	at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:845) ~[spring-beans-5.1.8.RELEASE.jar:5.1.8.RELEASE]
	at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:877) ~[spring-context-5.1.8.RELEASE.jar:5.1.8.RELEASE]
	at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:549) ~[spring-context-5.1.8.RELEASE.jar:5.1.8.RELEASE]
	at org.springframework.boot.web.reactive.context.ReactiveWebServerApplicationContext.refresh(ReactiveWebServerApplicationContext.java:66) ~[spring-boot-2.1.6.RELEASE.jar:2.1.6.RELEASE]
	at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:742) [spring-boot-2.1.6.RELEASE.jar:2.1.6.RELEASE]
	at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:389) [spring-boot-2.1.6.RELEASE.jar:2.1.6.RELEASE]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:311) [spring-boot-2.1.6.RELEASE.jar:2.1.6.RELEASE]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1213) [spring-boot-2.1.6.RELEASE.jar:2.1.6.RELEASE]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1202) [spring-boot-2.1.6.RELEASE.jar:2.1.6.RELEASE]
	at com.pupa.mall.gateway.GatewayApplication.main(GatewayApplication.java:18) [classes/:na]
Caused by: java.lang.IllegalStateException: Failed to introspect Class [org.springframework.boot.web.servlet.ServletRegistrationBean] from ClassLoader [sun.misc.Launcher$AppClassLoader@18b4aac2]
	at org.springframework.util.ReflectionUtils.getDeclaredMethods(ReflectionUtils.java:507) ~[spring-core-5.1.8.RELEASE.jar:5.1.8.RELEASE]
	at org.springframework.util.ReflectionUtils.doWithLocalMethods(ReflectionUtils.java:367) ~[spring-core-5.1.8.RELEASE.jar:5.1.8.RELEASE]
	at org.springframework.beans.factory.annotation.InitDestroyAnnotationBeanPostProcessor.buildLifecycleMetadata(InitDestroyAnnotationBeanPostProcessor.java:207) ~[spring-beans-5.1.8.RELEASE.jar:5.1.8.RELEASE]
	at org.springframework.beans.factory.annotation.InitDestroyAnnotationBeanPostProcessor.findLifecycleMetadata(InitDestroyAnnotationBeanPostProcessor.java:189) ~[spring-beans-5.1.8.RELEASE.jar:5.1.8.RELEASE]
	at org.springframework.beans.factory.annotation.InitDestroyAnnotationBeanPostProcessor.postProcessMergedBeanDefinition(InitDestroyAnnotationBeanPostProcessor.java:128) ~[spring-beans-5.1.8.RELEASE.jar:5.1.8.RELEASE]
	at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor.postProcessMergedBeanDefinition(CommonAnnotationBeanPostProcessor.java:297) ~[spring-context-5.1.8.RELEASE.jar:5.1.8.RELEASE]
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.applyMergedBeanDefinitionPostProcessors(AbstractAutowireCapableBeanFactory.java:1077) ~[spring-beans-5.1.8.RELEASE.jar:5.1.8.RELEASE]
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:567) ~[spring-beans-5.1.8.RELEASE.jar:5.1.8.RELEASE]
	... 15 common frames omitted
Caused by: java.lang.NoClassDefFoundError: javax/servlet/ServletRegistration$Dynamic
	at java.lang.Class.getDeclaredMethods0(Native Method) ~[na:1.8.0_333]
	at java.lang.Class.privateGetDeclaredMethods(Class.java:2701) ~[na:1.8.0_333]
	at java.lang.Class.getDeclaredMethods(Class.java:1975) ~[na:1.8.0_333]
	at org.springframework.util.ReflectionUtils.getDeclaredMethods(ReflectionUtils.java:489) ~[spring-core-5.1.8.RELEASE.jar:5.1.8.RELEASE]
	... 22 common frames omitted
Caused by: java.lang.ClassNotFoundException: javax.servlet.ServletRegistration$Dynamic
	at java.net.URLClassLoader.findClass(URLClassLoader.java:387) ~[na:1.8.0_333]
	at java.lang.ClassLoader.loadClass(ClassLoader.java:418) ~[na:1.8.0_333]
	at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:355) ~[na:1.8.0_333]
	at java.lang.ClassLoader.loadClass(ClassLoader.java:351) ~[na:1.8.0_333]
	... 26 common frames omitted

引起如上错误的主要原因是pom.xml中引入的依赖有误

<dependency>
    <groupId>javax.servlet</groupId>
    <artifactId>servlet-api</artifactId>
</dependency>

更换为:

<dependency>
    <groupId>javax.servlet</groupId>
    <artifactId>javax.servlet-api</artifactId>
</dependency>

至此问题解决
撒花....