这是由于默认配置下eureka会把自己当成了客户端来注册自己。（在启动的时候，它会同时把自己当成客户端来注册自己。而在启动的过程中。它自己即使服务端又是客户端。服务端都还没启动好，客户端就去找肯定会报错！）
--- [ restartedMain] : Started PaymenMain8001 in 10.393 seconds (JVM running for 115.475)
--- [ restartedMain] .ConditionEvaluationDeltaLoggingListener : Condition evaluation unchanged
--- [nfoReplicator-0] c.n.d.s.t.d.RedirectingEurekaHttpClient : Request execution error. endpoint=DefaultEndpoint{ serviceUrl='http://localhost:8761/eureka/}
com.sun.jersey.api.client.ClientHandlerException: java.net.ConnectException: Connection refused: connect
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-1.9.13.jar:1.9.13]
at com.netflix.discovery.shared.transport.decorator.EurekaHttpClientDecorator.register(EurekaHttpClientDecorator.java:56) ~[eureka-client-1.9.13.jar:1.9.13]
at com.netflix.discovery.shared.transport.decorator.EurekaHttpClientDecorator$1.execute(EurekaHttpClientDecorator.java:59) ~[eureka-client-1.9.13.jar:1.9.13]
at com.netflix.discovery.shared.transport.decorator.SessionedEurekaHttpClient.execute(SessionedEurekaHttpClient.java:77) ~[eureka-client-1.9.13.jar:1.9.13]
at com.netflix.discovery.shared.transport.decorator.EurekaHttpClientDecorator.register(EurekaHttpClientDecorator.java:56) ~[eureka-client-1.9.13.jar:1.9.13]
at com.netflix.discovery.DiscoveryClient.register(DiscoveryClient.java:847) ~[eureka-client-1.9.13.jar:1.9.13]
at com.netflix.discovery.InstanceInfoReplicator.run(InstanceInfoReplicator.java:121) ~[eureka-client-1.9.13.jar:1.9.13]
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511) [na:1.8.0_152]
at java.util.concurrent.FutureTask.run(FutureTask.java:266) [na:1.8.0_152]
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$201(ScheduledThreadPoolExecutor.java:180) [na:1.8.0_152]
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:293) [na:1.8.0_152]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [na:1.8.0_152]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [na:1.8.0_152]
at java.lang.Thread.run(Thread.java:748) [na:1.8.0_152]
所以我们需要禁用它的客户端默认的注册行为。在yml文件中加入：
eureka:
client:
register-with-eureka:false 是否将自己注册到Eureka Server上，默认为true
fetch-registry:false 是否从Eureka Server上获取注册信息，默认为true
它默认的注册地址是：http://localhost:8761/eureka/，如果在不禁用默认配置的情况下把注册中心的地址改成这个。启动时还是会报一次错，因为都还启动，肯定会报错
