一路坎坷，记录下来。
1. External libraries 下面没出现maven 包。
我这个是修复好了。重建了N次
解决1： 点击图中箭头所指图标，有时候好使，需要试试。
解决2：如下图，删的只留下两个文件重启。
2. @SpringBootApplication 报红
@SpringBootApplication import org.springframework.boot.SpringApplication; 报红我使用的是spring 2.0.0.RELEASE,百度了下，加上下面的 依赖就可以了
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-aop</artifactId>
</dependency>3.@EnableEurekaServer 注解无法使用
需要下载eurkaserver 依赖，也可能是依赖下载出错了。需要删掉重新下载。通过右侧maven栏可以看到有没有标红的，或者IDEA 点击 file --> project structure --> modules --> dependencies 看下有没有depend 报红，报红就说明有包下载不成功。
4. 启动spring boot 报错
错误信息， 找不到 class config什么Bean
这个是spring boot 和eurka 依赖版本不一致，需要百度下对应支持的版本号，下载对应的。
https://blog.csdn.net/kang9399052316/article/details/106047465/
5. maven 依赖下载不下载
疯狂 dowload 无效，Reimport 无效，修改pom 下载无效。
这时候可能是 maven setting 文件配置的问题
右击项目，选择maven，选择 open setting.xml 。
找到 mirrors ，检查下 mirrorOf 里面是 * 还是什么。* 代表所有的，不是就修改下。有时候阿里云的好像下载不下来，需要换成官网的，速度就比较慢了。
<mirror>
<id>alimaven</id>
<name>aliyun maven</name>
<url>https://maven.aliyun.com/repository/public/</url>
<mirrorOf>*</mirrorOf>
</mirror>eurekaAutoServiceRegistration 异常
org.springframework.context.ApplicationContextException: Failed to start bean 'eurekaAutoServiceRegistration'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'scopedTarget.eurekaApplicationInfoManager' defined in class path resource [org/springframework/cloud/netflix/eureka/EurekaClientAutoConfiguration$RefreshableEurekaClientConfiguration.class]: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [com.netflix.appinfo.ApplicationInfoManager]: Factory method 'eurekaApplicationInfoManager' threw exception; nested exception is java.lang.NullPointerException
at org.springframework.context.support.DefaultLifecycleProcessor.doStart(DefaultLifecycleProcessor.java:185) ~[spring-context-5.2.5.RELEASE.jar:5.2.5.RELEASE]
at org.springframework.context.support.DefaultLifecycleProcessor.access$200(DefaultLifecycleProcessor.java:53) ~[spring-context-5.2.5.RELEASE.jar:5.2.5.RELEASE]
at org.springframework.context.support.DefaultLifecycleProcessor$LifecycleGroup.start(DefaultLifecycleProcessor.java:360) ~[spring-context-5.2.5.RELEASE.jar:5.2.5.RELEASE]
at org.springframework.context.support.DefaultLifecycleProcessor.startBeans(DefaultLifecycleProcessor.java:158) ~[spring-context-5.2.5.RELEASE.jar:5.2.5.RELEASE]
at org.springframework.context.support.DefaultLifecycleProcessor.onRefresh(DefaultLifecycleProcessor.java:122) ~[spring-context-5.2.5.RELEASE.jar:5.2.5.RELEASE]
at org.springframework.context.support.AbstractApplicationContext.finishRefresh(AbstractApplicationContext.java:894) ~[spring-context-5.2.5.RELEASE.jar:5.2.5.RELEASE]
at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.finishRefresh(ServletWebServerApplicationContext.java:162) ~[spring-boot-2.2.6.RELEASE.jar:2.2.6.RELEASE]
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:553) ~[spring-context-5.2.5.RELEASE.jar:5.2.5.RELEASE]
at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:141) ~[spring-boot-2.2.6.RELEASE.jar:2.2.6.RELEASE]
at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:747) [spring-boot-2.2.6.RELEASE.jar:2.2.6.RELEASE]
at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:397) [spring-boot-2.2.6.RELEASE.jar:2.2.6.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:315) [spring-boot-2.2.6.RELEASE.jar:2.2.6.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1226) [spring-boot-2.2.6.RELEASE.jar:2.2.6.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1215) [spring-boot-2.2.6.RELEASE.jar:2.2.6.RELEASE]
at com.dandan.eureka.demoeurekaclient.DemoEurekaClientApplication.main(DemoEurekaClientApplication.java:13) [classes/:na]
Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'scopedTarget.eurekaApplicationInfoManager' defined in class path resource [org/springframework/cloud/netflix/eureka/EurekaClientAutoConfiguration$RefreshableEurekaClientConfiguration.class]: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [com.netflix.appinfo.ApplicationInfoManager]: Factory method 'eurekaApplicationInfoManager' threw exception; nested exception is java.lang.NullPointerException
at org.springframework.beans.factory.support.ConstructorResolver.instantiate(ConstructorResolver.java:656) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]
at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:636) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:1338) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1177) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:557) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:517) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$1(AbstractBeanFactory.java:359) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]
at org.springframework.cloud.context.scope.GenericScope$BeanLifecycleWrapper.getBean(GenericScope.java:389) ~[spring-cloud-context-2.2.2.RELEASE.jar:2.2.2.RELEASE]
at org.springframework.cloud.context.scope.GenericScope.get(GenericScope.java:186) ~[spring-cloud-context-2.2.2.RELEASE.jar:2.2.2.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:356) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:202) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]
at org.springframework.aop.target.SimpleBeanTargetSource.getTarget(SimpleBeanTargetSource.java:35) ~[spring-aop-5.2.5.RELEASE.jar:5.2.5.RELEASE]
at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:675) ~[spring-aop-5.2.5.RELEASE.jar:5.2.5.RELEASE]
at com.netflix.appinfo.ApplicationInfoManager$$EnhancerBySpringCGLIB$$8c9b3909.getInfo(<generated>) ~[eureka-client-1.9.17.jar:1.9.17]
at org.springframework.cloud.netflix.eureka.serviceregistry.EurekaServiceRegistry.maybeInitializeClient(EurekaServiceRegistry.java:56) ~[spring-cloud-netflix-eureka-client-2.2.2.RELEASE.jar:2.2.2.RELEASE]
at org.springframework.cloud.netflix.eureka.serviceregistry.EurekaServiceRegistry.register(EurekaServiceRegistry.java:38) ~[spring-cloud-netflix-eureka-client-2.2.2.RELEASE.jar:2.2.2.RELEASE]
at org.springframework.cloud.netflix.eureka.serviceregistry.EurekaAutoServiceRegistration.start(EurekaAutoServiceRegistration.java:83) ~[spring-cloud-netflix-eureka-client-2.2.2.RELEASE.jar:2.2.2.RELEASE]
at org.springframework.context.support.DefaultLifecycleProcessor.doStart(DefaultLifecycleProcessor.java:182) ~[spring-context-5.2.5.RELEASE.jar:5.2.5.RELEASE]
... 14 common frames omitted这个是启动eureka-client 的时候报的异常。
百度的结果各种不对。最后通过自己调试找到的。
一路追踪之下，如图
解决： eureka 一定要配 eureka.instance.hostname=localhost