下文是从stackoverflow上面找到的对这两者的解释：
There are multiple implementations of "Discovery Service" (eureka, consul, zookeeper). @EnableDiscoveryClient lives in spring-cloud-commons and picks the implementation on the classpath. @EnableEurekaClient lives in spring-cloud-netflix and only works for eureka. If eureka is on your classpath, they are effectively the same.
原文地址为:What’s the difference between EnableEurekaClient and EnableDiscoveryClient?
意思也就是spring cloud中discovery service有许多种实现（eureka、consul、zookeeper等等），@EnableDiscoveryClient基于spring-cloud-commons, @EnableEurekaClient基于spring-cloud-netflix。
其实用更简单的话来说，就是如果选用的注册中心是eureka，那么就推荐@EnableEurekaClient，如果是其他的注册中心，那么推荐使用@EnableDiscoveryClient。
1、@EnableEurekaClient
我们具体的对@EnableEurekaClient的源码看一下，如下：
/**
* Convenience annotation for clients to enable Eureka discovery configuration
* (specifically). Use this (optionally) in case you want discovery and know for sure that
* it is Eureka you want. All it does is turn on discovery and let the autoconfiguration
* find the eureka classes if they are available (i.e. you need Eureka on the classpath as
* well).
*
* @author Dave Syer
* @author Spencer Gibb
*/
@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Inherited
@EnableDiscoveryClient
public @interface EnableEurekaClient { }
注解@EnableEurekaClient上有@EnableDiscoveryClient注解，可以说基本就是EnableEurekaClient有@EnableDiscoveryClient的功能，另外上面的注释中提到，其实**@EnableEurekaClient**z注解就是一种方便使用eureka的注解而已，可以说使用其他的注册中心后，都可以使用@EnableDiscoveryClient注解，但是使用@EnableEurekaClient的情景，就是在服务采用eureka作为注册中心的时候，使用场景较为单一。
Spring boot 2.0之后，@EnableEurekaClient已经不是由@EnableDiscoveryClient实现的了。
/**
* Convenience annotation for clients to enable Eureka discovery configuration
* (specifically). Use this (optionally) in case you want discovery and know for sure that
* it is Eureka you want. All it does is turn on discovery and let the autoconfiguration
* find the eureka classes if they are available (i.e. you need Eureka on the classpath as
* well).
*
* @author Dave Syer
* @author Spencer Gibb
*/
@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Inherited
public @interface EnableEurekaClient {
} 2、@EurekaDiscoveryClient
/**
* Annotation to enable a DiscoveryClient implementation.
* @author Spencer Gibb
*/ @Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Inherited
@Import(EnableDiscoveryClientImportSelector.class)
public @interface EnableDiscoveryClient { }
注解@EnableDiscoveryClient上有注解@Import(EnableDiscoveryClientImportSelector.class)修饰，@Import不仅可以单独导入一个配置，另外也可以导入普通的java类，并将其声明为一个bean。此处导入EnableDiscoveryClientImportSelector.class后，加载我们用到的bean，EnableDiscoveryClientImportSelector.class源码如下：
/**
* @author Spencer Gibb
*/
@Order(Ordered.LOWEST_PRECEDENCE - 100)
public class EnableDiscoveryClientImportSelector extends SpringFactoryImportSelector<EnableDiscoveryClient> {
@Override protected boolean isEnabled() {
return new RelaxedPropertyResolver(
getEnvironment()).getProperty( "spring.cloud.discovery.enabled", Boolean.class, Boolean.TRUE);
}
@Override protected boolean hasDefaultFactory() {
return true;
}
}
这个类中有一个覆盖父类的方法isEnabled(),返回默认为true，那么说明只要是引入了EnableDiscoveryClientImportSelector类，spring.cloud.discovery.enabled就处于enable状态。
EnableDiscoveryClientImportSelector继承了类SpringFactoryImportSelector。
在关键的方法selectImports中:
// Find all possible auto configuration classes, filtering duplicates
List<String> factories = new ArrayList<>(
new LinkedHashSet<>(SpringFactoriesLoader .loadFactoryNames(this.annotationClass, this.beanClassLoader)));
根据这一步来找到configuration class,这里的SpringFactoriesLoader.loadFactoryNames就是根据配置文件来load class，转到SpringFactoriesLoader.loadFactoryNames。
。。。。。
原文:https://blog.csdn.net/u012734441/article/details/78315086