0. 环境

eureka版本：1.10.11 Spring Cloud : 2020.0.2 Spring Boot ：2.4.4
测试代码：github.com/hsfxuebao/s…hni拜客生活常识网

1. 前言

本文主要是解析下Spring Cloud整合Eureka Client的源码，这块代码比较多，而且都是些简单代码，我们稍微看下就行，这就是介绍下Eureka Client初始化过程，不管你Spring Cloud 怎样封装，底层还是Eureka Client的内容，初始化过程包括下面：hni拜客生活常识网

1. 去Eureka Server 拉取全量注册表，
2. 创建定时任务，包括定时去Eureka Server 上增量拉取注册表信息，定时renew （服务续约）。
3. 服务注册

2. Spring Cloud整合Eureka Client 启动入口

要看Spring Cloud 怎样整合 Eureka Client ，就需要找到它们的自动装配配置类 在spring-cloud-starter-netflix-eureka-client 依赖的pom文件中，在依赖pom文件中有spring-cloud-netflix-eureka-client， 在这个里面能够找到spring.factories 文件，这个文件是spring spi文件。hni拜客生活常识网

hni拜客生活常识网

核心就是EurekaClientAutoConfiguration 这个自动装配类:hni拜客生活常识网

@Configuration(proxyBeanMethods = false)
@EnableConfigurationProperties
@ConditionalOnClass(EurekaClientConfig.class)
@ConditionalOnProperty(value = "eureka.client.enabled", matchIfMissing = true)
@ConditionalOnDiscoveryEnabled
@AutoConfigureBefore({ CommonsClientAutoConfiguration.class, ServiceRegistryAutoConfiguration.class })
@AutoConfigureAfter(name = { "org.springframework.cloud.netflix.eureka.config.DiscoveryClientOptionalArgsConfiguration",
      "org.springframework.cloud.autoconfigure.RefreshAutoConfiguration",
      "org.springframework.cloud.netflix.eureka.EurekaDiscoveryClientConfiguration",
      "org.springframework.cloud.client.serviceregistry.AutoServiceRegistrationAutoConfiguration" })
public class EurekaClientAutoConfiguration {
}

2.1 封装配置文件的类

2.1.1 EurekaClientConfigBean

@Bean
@ConditionalOnMissingBean(value = EurekaClientConfig.class, search = SearchStrategy.CURRENT)
public EurekaClientConfigBean eurekaClientConfigBean(ConfigurableEnvironment env) {
   return new EurekaClientConfigBean();
}

其读取的是eureka.client前辍的配置信息。这个类已经被@ConfigurationProperties注解了，所以这些 配置信息可以被自动封装并注册到容器。hni拜客生活常识网

hni拜客生活常识网

2.1.2 EurekaInstanceConfigBean

@Bean
@ConditionalOnMissingBean(value = EurekaInstanceConfig.class, search = SearchStrategy.CURRENT)
public EurekaInstanceConfigBean eurekaInstanceConfigBean(InetUtils inetUtils,
      ManagementMetadataProvider managementMetadataProvider) {
}

其读取的是eureka.instance的属性值。这个类也已经被@ConfigurationProperties注解了，所以这些配 置信息可以被自动封装并注册到容器。hni拜客生活常识网

hni拜客生活常识网

2.2 EurekaClient

接下来，看看核心类EurekaClient是怎么注入进去的？ 在EurekaClientAutoConfiguration文件中，我们发现有两个地方都可以注入EurekaClient,分别为：hni拜客生活常识网

@Configuration(proxyBeanMethods = false)
@ConditionalOnMissingRefreshScope
protected static class EurekaClientConfiguration {

   @Bean(destroyMethod = "shutdown")
   @ConditionalOnMissingBean(value = EurekaClient.class, search = SearchStrategy.CURRENT)
   public EurekaClient eurekaClient(ApplicationInfoManager manager, EurekaClientConfig config) {
      return new CloudEurekaClient(manager, config, this.optionalArgs, this.context);
   }
}

// 另一个是：
@Configuration(proxyBeanMethods = false)
@ConditionalOnRefreshScope
protected static class RefreshableEurekaClientConfiguration {

   @Bean(destroyMethod = "shutdown")
   @ConditionalOnMissingBean(value = EurekaClient.class, search = SearchStrategy.CURRENT)
   @org.springframework.cloud.context.config.annotation.RefreshScope
   @Lazy
   public EurekaClient eurekaClient(ApplicationInfoManager manager, EurekaClientConfig config,
         EurekaInstanceConfig instance, @Autowired(required = false) HealthCheckHandler healthCheckHandler) {
      }

}

这就需要分析到底哪一个注解生效了？

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