1、根据自动装配原理（详见：Spring Boot系列（二）：Spring Boot自动装配原理解析），找到spring-cloud-netflix-eureka-client.jar的spring.factories，查看spring.factories如下：
2、进入EurekaClient的自动装配类EurekaClientAutoConfiguration：
3、@ConditionalOnBean(EurekaDiscoveryClientConfiguration.Marker.class)也就是说当容器中有EurekaDiscoveryClientCon figuration.Marker.class时，该配置类才起作用。接下来查看spring.factories，发现还有一个配置类EurekaDiscoveryClientConfigura tion，该配置类就刚刚好往容器中导入了EurekaDiscoveryClientConfiguration.Marker。
二、EurekaClient 1、EurekaClientAutoConfiguration配置类 1.1 导入的核心Bean① EurekaClientConfigBean：初始化eurekaClient配置；
② EurekaInstanceConfigBean：初始化eureka实例配置；
③ EurekaDiscoveryClient：初始化eureka发现客户端；
④ EurekaServiceRegistry：初始化eureka服务注册；
⑤ EurekaAutoServiceRegistration：初始化eureka自动服务注册；
⑥ EurekaClient：初始化eureka客户端；
1.2 初始化EurekaClient① 首先看下类的继承图：
② CloudEurekaClient构造方法：
点进去会发现它调用父类的构造方法super(applicationInfoManager, config, args);最终来到如下方法：
@Inject DiscoveryClient(ApplicationInfoManager applicationInfoManager, EurekaClientConfig config, AbstractDiscoveryClientOptionalArgs args, Provider<BackupRegistry> backupRegistryProvider, EndpointRandomizer endpointRandomizer) { //省略...... this.applicationInfoManager = applicationInfoManager; //1、获取要注册的服务实例信息 InstanceInfo myInfo = applicationInfoManager.getInfo(); //省略...... instanceInfo = myInfo; //省略...... //2、定义一些Executor try { // default size of 2 - 1 each for heartbeat and cacheRefresh scheduler = Executors.newScheduledThreadPool(2, new ThreadFactoryBuilder() .setNameFormat("DiscoveryClient-%d") .setDaemon(true) .build()); //心跳Executor heartbeatExecutor = new ThreadPoolExecutor( 1, clientConfig.getHeartbeatExecutorThreadPoolSize(), 0, TimeUnit.SECONDS, new SynchronousQueue<Runnable>(), new ThreadFactoryBuilder() .setNameFormat("DiscoveryClient-HeartbeatExecutor-%d") .setDaemon(true) .build() ); // use direct handoff //本地缓存刷新Executor cacheRefreshExecutor = new ThreadPoolExecutor( 1, clientConfig.getCacheRefreshExecutorThreadPoolSize(), 0, TimeUnit.SECONDS, new SynchronousQueue<Runnable>(), new ThreadFactoryBuilder() .setNameFormat("DiscoveryClient-CacheRefreshExecutor-%d") .setDaemon(true) .build() ); // use direct handoff /** * 1、初始化定时拉取服务注册信息和服务续约任务 * 2、定义一个状态变化监听 * 3、初始化定时服务注册任务 */ initScheduledTasks(); //省略...... }