spring cloud eureka客户端报错com.netflix.discovery.shared.transport.TransportException

异常时控制台的输出：

2020-04-08 16:47:38.076  INFO 5408 --- [           main] com.netflix.discovery.DiscoveryClient    : Getting all instance registry info from the eureka server
2020-04-08 16:47:38.241  WARN 5408 --- [           main] c.n.d.s.t.d.RetryableEurekaHttpClient    : Request execution failure with status code 404; retrying on another server if available
2020-04-08 16:47:38.246 ERROR 5408 --- [           main] com.netflix.discovery.DiscoveryClient    : DiscoveryClient_EUREKA-CLIENT-DEMO1/127.0.0.1:8001 - was unable to refresh its cache! status = Cannot execute request on any known server

com.netflix.discovery.shared.transport.TransportException: Cannot execute request on any known server
	at com.netflix.discovery.shared.transport.decorator.RetryableEurekaHttpClient.execute(RetryableEurekaHttpClient.java:112) ~[eureka-client-1.9.2.jar:1.9.2]
	at com.netflix.discovery.shared.transport.decorator.EurekaHttpClientDecorator.getApplications(EurekaHttpClientDecorator.java:134) ~[eureka-client-1.9.2.jar:1.9.2]
	at com.netflix.discovery.shared.transport.decorator.EurekaHttpClientDecorator$6.execute(EurekaHttpClientDecorator.java:137) ~[eureka-client-1.9.2.jar:1.9.2]
	at com.netflix.discovery.shared.transport.decorator.SessionedEurekaHttpClient.execute(SessionedEurekaHttpClient.java:77) ~[eureka-client-1.9.2.jar:1.9.2]
	at com.netflix.discovery.shared.transport.decorator.EurekaHttpClientDecorator.getApplications(EurekaHttpClientDecorator.java:134) ~[eureka-client-1.9.2.jar:1.9.2]
	at com.netflix.discovery.DiscoveryClient.getAndStoreFullRegistry(DiscoveryClient.java:1051) [eureka-client-1.9.2.jar:1.9.2]
	at com.netflix.discovery.DiscoveryClient.fetchRegistry(DiscoveryClient.java:965) [eureka-client-1.9.2.jar:1.9.2]
	at com.netflix.discovery.DiscoveryClient.(DiscoveryClient.java:414) [eureka-client-1.9.2.jar:1.9.2]
	at com.netflix.discovery.DiscoveryClient.(DiscoveryClient.java:269) [eureka-client-1.9.2.jar:1.9.2]
	at org.springframework.cloud.netflix.eureka.CloudEurekaClient.(CloudEurekaClient.java:63) [spring-cloud-netflix-eureka-client-2.0.0.RELEASE.jar:2.0.0.RELEASE]
	at org.springframework.cloud.netflix.eureka.EurekaClientAutoConfiguration$RefreshableEurekaClientConfiguration.eurekaClient(EurekaClientAutoConfiguration.java:269) [spring-cloud-netflix-eureka-client-2.0.0.RELEASE.jar:2.0.0.RELEASE]
	at org.springframework.cloud.netflix.eureka.EurekaClientAutoConfiguration$RefreshableEurekaClientConfiguration$$EnhancerBySpringCGLIB$$6e671502.CGLIB$eurekaClient$0() [spring-cloud-netflix-eureka-client-2.0.0.RELEASE.jar:2.0.0.RELEASE]
	at org.springframework.cloud.netflix.eureka.EurekaClientAutoConfiguration$RefreshableEurekaClientConfiguration$$EnhancerBySpringCGLIB$$6e671502$$FastClassBySpringCGLIB$$b2360358.invoke() [spring-cloud-netflix-eureka-client-2.0.0.RELEASE.jar:2.0.0.RELEASE]
	at org.springframework.cglib.proxy.MethodProxy.invokeSuper(MethodProxy.java:228) [spring-core-5.0.7.RELEASE.jar:5.0.7.RELEASE]
	at org.springframework.context.annotation.ConfigurationClassEnhancer$BeanMethodInterceptor.intercept(ConfigurationClassEnhancer.java:361) [spring-context-5.0.7.RELEASE.jar:5.0.7.RELEASE]
	at org.springframework.cloud.netflix.eureka.EurekaClientAutoConfiguration$RefreshableEurekaClientConfiguration$$EnhancerBySpringCGLIB$$6e671502.eurekaClient() [spring-cloud-netflix-eureka-client-2.0.0.RELEASE.jar:2.0.0.RELEASE]
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_221]
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_221]
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_221]
	at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_221]
	at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:154) [spring-beans-5.0.7.RELEASE.jar:5.0.7.RELEASE]
	at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:582) [spring-beans-5.0.7.RELEASE.jar:5.0.7.RELEASE]
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:1256) [spring-beans-5.0.7.RELEASE.jar:5.0.7.RELEASE]
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1105) [spring-beans-5.0.7.RELEASE.jar:5.0.7.RELEASE]
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:543) [spring-beans-5.0.7.RELEASE.jar:5.0.7.RELEASE]
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:503) [spring-beans-5.0.7.RELEASE.jar:5.0.7.RELEASE]
	at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$1(AbstractBeanFactory.java:353) [spring-beans-5.0.7.RELEASE.jar:5.0.7.RELEASE]
	at org.springframework.cloud.context.scope.GenericScope$BeanLifecycleWrapper.getBean(GenericScope.java:390) ~[spring-cloud-context-2.0.0.RELEASE.jar:2.0.0.RELEASE]
	at org.springframework.cloud.context.scope.GenericScope.get(GenericScope.java:184) ~[spring-cloud-context-2.0.0.RELEASE.jar:2.0.0.RELEASE]
	at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:350) [spring-beans-5.0.7.RELEASE.jar:5.0.7.RELEASE]
	at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:199) [spring-beans-5.0.7.RELEASE.jar:5.0.7.RELEASE]
	at org.springframework.aop.target.SimpleBeanTargetSource.getTarget(SimpleBeanTargetSource.java:35) ~[spring-aop-5.0.7.RELEASE.jar:5.0.7.RELEASE]
	at org.springframework.cloud.netflix.eureka.serviceregistry.EurekaRegistration.getTargetObject(EurekaRegistration.java:167) ~[spring-cloud-netflix-eureka-client-2.0.0.RELEASE.jar:2.0.0.RELEASE]
	at org.springframework.cloud.netflix.eureka.serviceregistry.EurekaRegistration.getEurekaClient(EurekaRegistration.java:156) ~[spring-cloud-netflix-eureka-client-2.0.0.RELEASE.jar:2.0.0.RELEASE]
	at org.springframework.cloud.netflix.eureka.serviceregistry.EurekaServiceRegistry.maybeInitializeClient(EurekaServiceRegistry.java:57) ~[spring-cloud-netflix-eureka-client-2.0.0.RELEASE.jar:2.0.0.RELEASE]
	at org.springframework.cloud.netflix.eureka.serviceregistry.EurekaServiceRegistry.register(EurekaServiceRegistry.java:39) ~[spring-cloud-netflix-eureka-client-2.0.0.RELEASE.jar:2.0.0.RELEASE]
	at org.springframework.cloud.netflix.eureka.serviceregistry.EurekaAutoServiceRegistration.start(EurekaAutoServiceRegistration.java:80) ~[spring-cloud-netflix-eureka-client-2.0.0.RELEASE.jar:2.0.0.RELEASE]
	at org.springframework.context.support.DefaultLifecycleProcessor.doStart(DefaultLifecycleProcessor.java:181) ~[spring-context-5.0.7.RELEASE.jar:5.0.7.RELEASE]
	at org.springframework.context.support.DefaultLifecycleProcessor.access$200(DefaultLifecycleProcessor.java:52) ~[spring-context-5.0.7.RELEASE.jar:5.0.7.RELEASE]
	at org.springframework.context.support.DefaultLifecycleProcessor$LifecycleGroup.start(DefaultLifecycleProcessor.java:356) ~[spring-context-5.0.7.RELEASE.jar:5.0.7.RELEASE]
	at org.springframework.context.support.DefaultLifecycleProcessor.startBeans(DefaultLifecycleProcessor.java:157) ~[spring-context-5.0.7.RELEASE.jar:5.0.7.RELEASE]
	at org.springframework.context.support.DefaultLifecycleProcessor.onRefresh(DefaultLifecycleProcessor.java:121) ~[spring-context-5.0.7.RELEASE.jar:5.0.7.RELEASE]
	at org.springframework.context.support.AbstractApplicationContext.finishRefresh(AbstractApplicationContext.java:885) ~[spring-context-5.0.7.RELEASE.jar:5.0.7.RELEASE]
	at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.finishRefresh(ServletWebServerApplicationContext.java:161) ~[spring-boot-2.0.3.RELEASE.jar:2.0.3.RELEASE]
	at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:553) ~[spring-context-5.0.7.RELEASE.jar:5.0.7.RELEASE]
	at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:140) ~[spring-boot-2.0.3.RELEASE.jar:2.0.3.RELEASE]
	at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:759) ~[spring-boot-2.0.3.RELEASE.jar:2.0.3.RELEASE]
	at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:395) ~[spring-boot-2.0.3.RELEASE.jar:2.0.3.RELEASE]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:327) ~[spring-boot-2.0.3.RELEASE.jar:2.0.3.RELEASE]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1255) ~[spring-boot-2.0.3.RELEASE.jar:2.0.3.RELEASE]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1243) ~[spring-boot-2.0.3.RELEASE.jar:2.0.3.RELEASE]
	at com.tang.cloud.service.App.main(App.java:13) ~[classes/:na]

注意看关键信息：
Getting all instance registry info from the eureka server
翻译成中文就是从eureka服务器获取所有实例的注册表，所有错误都紧跟这个log之后，证明就是获取eureka注册表时报的错。
Request execution failure with status code 404; retrying on another server if available
翻译成中文就是连接eureka服务器404，正在尝试连接其他激活的eureka服务器
was unable to refresh its cache! status = Cannot execute request on any known server
翻译成中文就是无法刷新eureka客户端的注册表本地缓存，状态为“无法在任何已知eureka服务器上请求到注册表”

连接eureka服务器404的原因，要么eureka服务器没有启动，要么eureka服务器启动了安全校验，连不上，要么就是eureka客户端的连接eureka服务器的url写错了。
我的eureka服务器启动无报错，启动后可在浏览器访问，证明eureka服务器没问题。
我的eureka服务器没有导入spring security相关maven以及与spring security类似的其他任何安全框架，证明不是安全校验的问题。

最后只剩下服务器url拼写错误，可我仔细检查了url没有发现问题，下面是我的配置文件：
eureka服务器：

server.port=8000
#spring boot2.0 之后使用 server.servlet.context-path 否则使用 server.context-path
server.servlet.context-path=/eureka
#spring cloud项目微服务的服务名
spring.application.name=eureka
#是否将自己注册到Eureka Server上，默认为true
eureka.client.register-with-eureka=false
#是否从Eureka Server上获取注册信息，默认为true
eureka.client.fetch-registry=false

eureka客户端：

server.port=8001
spring.application.name=service1
eureka.client.serviceUrl.defaultZone=http://localhost:8000/eureka/

最后看了博文：https://blog.csdn.net/feiz3020/article/details/80171839
才搞清楚确实是url错了，错在了服务器使用了server.servlet.context-path=/eureka
客户端必须使用eureka.client.serviceUrl.defaultZone=http://localhost:8000/eureka/eureka
客户端url里后面的那个eureka是固定死的不能改的，与服务器的真实访问路径无关！