Gateway启动报错java.lang.NoClassDefFoundError: javax/servlet/Servlet

版本情况

spring-boot :2.2.2.RELEASE
spring-cloud-alibaba:2.2.0.RELEASE
spring-cloud:Hoxton.SR1

geteway启动日志

2021-10-16 02:19:05.970  INFO 6648 --- [  restartedMain] o.s.b.devtools.restart.ChangeableUrls    : The Class-Path manifest attribute in D:\Repository\Maven\com\sun\xml\bind\jaxb-core\2.3.0.1\jaxb-core-2.3.0.1.jar referenced one or more files that do not exist: file:/D:/Repository/Maven/com/sun/xml/bind/jaxb-core/2.3.0.1/jaxb-api.jar
2021-10-16 02:19:05.971  INFO 6648 --- [  restartedMain] o.s.b.devtools.restart.ChangeableUrls    : The Class-Path manifest attribute in D:\Repository\Maven\com\sun\xml\bind\jaxb-impl\2.3.0.1\jaxb-impl-2.3.0.1.jar referenced one or more files that do not exist: file:/D:/Repository/Maven/com/sun/xml/bind/jaxb-impl/2.3.0.1/jaxb-core.jar
2021-10-16 02:19:05.971  INFO 6648 --- [  restartedMain] .e.DevToolsPropertyDefaultsPostProcessor : Devtools property defaults active! Set 'spring.devtools.add-properties' to 'false' to disable

  .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::        (v2.2.2.RELEASE)

2021-10-16 02:19:06.567  INFO 6648 --- [  restartedMain] c.a.n.c.c.impl.LocalConfigInfoProcessor  : LOCAL_SNAPSHOT_PATH:C:\Users\Lenovo\nacos\config
2021-10-16 02:19:06.580  INFO 6648 --- [  restartedMain] c.a.nacos.client.config.impl.Limiter     : limitTime:5.0
2021-10-16 02:19:06.594  INFO 6648 --- [  restartedMain] c.a.nacos.client.config.utils.JVMUtil    : isMultiInstance:false
2021-10-16 02:19:06.598  WARN 6648 --- [  restartedMain] c.a.c.n.c.NacosPropertySourceBuilder     : Ignore the empty nacos configuration and get it based on dataId[gateway-server] & group[DEFAULT_GROUP]
2021-10-16 02:19:06.601  WARN 6648 --- [  restartedMain] c.a.c.n.c.NacosPropertySourceBuilder     : Ignore the empty nacos configuration and get it based on dataId[gateway-server.yaml] & group[DEFAULT_GROUP]
2021-10-16 02:19:06.605  INFO 6648 --- [  restartedMain] b.c.PropertySourceBootstrapConfiguration : Located property source: [BootstrapPropertySource {name='bootstrapProperties-gateway-server-dev.yaml,DEFAULT_GROUP'}, BootstrapPropertySource {name='bootstrapProperties-gateway-server.yaml,DEFAULT_GROUP'}, BootstrapPropertySource {name='bootstrapProperties-gateway-server,DEFAULT_GROUP'}, BootstrapPropertySource {name='bootstrapProperties-common.yaml,DEFAULT_GROUP'}]
2021-10-16 02:19:06.608  INFO 6648 --- [  restartedMain] com.jltx.gateway.GatewayApplication      : The following profiles are active: dev
2021-10-16 02:19:07.010  WARN 6648 --- [  restartedMain] o.s.boot.actuate.endpoint.EndpointId     : Endpoint ID 'nacos-config' contains invalid characters, please migrate to a valid format.
2021-10-16 02:19:07.011  WARN 6648 --- [  restartedMain] o.s.boot.actuate.endpoint.EndpointId     : Endpoint ID 'nacos-discovery' contains invalid characters, please migrate to a valid format.
2021-10-16 02:19:07.113  INFO 6648 --- [  restartedMain] .s.d.r.c.RepositoryConfigurationDelegate : Multiple Spring Data modules found, entering strict repository configuration mode!
2021-10-16 02:19:07.114  INFO 6648 --- [  restartedMain] .s.d.r.c.RepositoryConfigurationDelegate : Bootstrapping Spring Data Redis repositories in DEFAULT mode.
2021-10-16 02:19:07.128  INFO 6648 --- [  restartedMain] .s.d.r.c.RepositoryConfigurationDelegate : Finished Spring Data repository scanning in 7ms. Found 0 Redis repository interfaces.
2021-10-16 02:19:07.178  WARN 6648 --- [  restartedMain] o.s.boot.actuate.endpoint.EndpointId     : Endpoint ID 'service-registry' contains invalid characters, please migrate to a valid format.
2021-10-16 02:19:07.244  INFO 6648 --- [  restartedMain] o.s.cloud.context.scope.GenericScope     : BeanFactory id=683cd207-b2f9-3ea9-9fd2-f0e560ebcd7c
2021-10-16 02:19:07.266 ERROR 6648 --- [  restartedMain] o.s.boot.SpringApplication               : Application run failed

java.lang.NoClassDefFoundError: javax/servlet/Servlet
	at java.lang.Class.getDeclaredConstructors0(Native Method) ~[na:1.8.0_131]
	at java.lang.Class.privateGetDeclaredConstructors(Class.java:2671) ~[na:1.8.0_131]
	at java.lang.Class.getDeclaredConstructors(Class.java:2020) ~[na:1.8.0_131]
	at org.springframework.boot.context.properties.ConfigurationPropertiesBindConstructorProvider.findConstructorBindingAnnotatedConstructor(ConfigurationPropertiesBindConstructorProvider.java:62) ~[spring-boot-2.2.2.RELEASE.jar:2.2.2.RELEASE]
	at org.springframework.boot.context.properties.ConfigurationPropertiesBindConstructorProvider.getBindConstructor(ConfigurationPropertiesBindConstructorProvider.java:48) ~[spring-boot-2.2.2.RELEASE.jar:2.2.2.RELEASE]
	at org.springframework.boot.context.properties.ConfigurationPropertiesBean$BindMethod.forType(ConfigurationPropertiesBean.java:311) ~[spring-boot-2.2.2.RELEASE.jar:2.2.2.RELEASE]
	at org.springframework.boot.context.properties.ConfigurationPropertiesBeanDefinitionValidator.validate(ConfigurationPropertiesBeanDefinitionValidator.java:63) ~[spring-boot-2.2.2.RELEASE.jar:2.2.2.RELEASE]
	at org.springframework.boot.context.properties.ConfigurationPropertiesBeanDefinitionValidator.postProcessBeanFactory(ConfigurationPropertiesBeanDefinitionValidator.java:45) ~[spring-boot-2.2.2.RELEASE.jar:2.2.2.RELEASE]
	at org.springframework.context.support.PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors(PostProcessorRegistrationDelegate.java:286) ~[spring-context-5.2.2.RELEASE.jar:5.2.2.RELEASE]
	at org.springframework.context.support.PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors(PostProcessorRegistrationDelegate.java:174) ~[spring-context-5.2.2.RELEASE.jar:5.2.2.RELEASE]
	at org.springframework.context.support.AbstractApplicationContext.invokeBeanFactoryPostProcessors(AbstractApplicationContext.java:706) ~[spring-context-5.2.2.RELEASE.jar:5.2.2.RELEASE]
	at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:532) ~[spring-context-5.2.2.RELEASE.jar:5.2.2.RELEASE]
	at org.springframework.boot.web.reactive.context.ReactiveWebServerApplicationContext.refresh(ReactiveWebServerApplicationContext.java:66) ~[spring-boot-2.2.2.RELEASE.jar:2.2.2.RELEASE]
	at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:747) [spring-boot-2.2.2.RELEASE.jar:2.2.2.RELEASE]
	at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:397) [spring-boot-2.2.2.RELEASE.jar:2.2.2.RELEASE]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:315) [spring-boot-2.2.2.RELEASE.jar:2.2.2.RELEASE]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1226) [spring-boot-2.2.2.RELEASE.jar:2.2.2.RELEASE]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1215) [spring-boot-2.2.2.RELEASE.jar:2.2.2.RELEASE]
	at com.jltx.gateway.GatewayApplication.main(GatewayApplication.java:12) [classes/:na]
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_131]
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_131]
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_131]
	at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_131]
	at org.springframework.boot.devtools.restart.RestartLauncher.run(RestartLauncher.java:49) [spring-boot-devtools-2.2.2.RELEASE.jar:2.2.2.RELEASE]
Caused by: java.lang.ClassNotFoundException: javax.servlet.Servlet
	at java.net.URLClassLoader.findClass(URLClassLoader.java:381) ~[na:1.8.0_131]
	at java.lang.ClassLoader.loadClass(ClassLoader.java:424) ~[na:1.8.0_131]
	at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:335) ~[na:1.8.0_131]
	at java.lang.ClassLoader.loadClass(ClassLoader.java:357) ~[na:1.8.0_131]
	... 24 common frames omitted

解决方法

去除父工程中的Druid,然后启动就可以了

	com.alibaba
	druid-spring-boot-starter
	1.1.10