Eureka

主要功能有：

1: 服务注册
2：服务续约
3：获取注册列表信息
4：服务剔除
5：服务下线

服务发现

核心注解： @EnableDiscoveryClient === @EnableEurekaClient

里面默认方法：autoRegister()

第一个：com.netflix.discovery

DiscoveryClient implements EurekaClient

public interface EurekaClient extends LookupService

在这个类里面包含了：

1：getServiceUrlsFromConfig 2：getServiceUrlsFromDNS 等方法.

DiscoveryClient里面：

 @Deprecated
    public List<String> getServiceUrlsFromConfig(String instanceZone, boolean preferSameZone) {
        return EndpointUtils.getServiceUrlsFromConfig(this.clientConfig, instanceZone, preferSameZone);
    }

进入EndPointUtils里面

getServiceUrlsMapFromConfig

region 只有一个，就是我们的集群

availZones 可以认为是多个机房

为啥默认是8761

EurekaClientConfigBean

在这个starter中，默认写了请求地址和前缀

public static final String PREFIX = "eureka.client";

public static final String DEFAULT_URL = "http://localhost:8761/eureka/";

public static final String DEFAULT_ZONE = "defaultZone";

1：服务发现方法

List serviceUrls = clientConfig.getEurekaServerServiceUrls(zone);

2：服务注册

DiscoveryClient.initScheduledTasks()

里面完成

1：抓取注册信息

registryFetchIntervalSeconds = 30

 if (this.clientConfig.shouldFetchRegistry()) {
            renewalIntervalInSecs = this.clientConfig.getRegistryFetchIntervalSeconds();
            expBackOffBound = this.clientConfig.getCacheRefreshExecutorExponentialBackOffBound();
            this.scheduler.schedule(new TimedSupervisorTask("cacheRefresh", this.scheduler, this.cacheRefreshExecutor, renewalIntervalInSecs, TimeUnit.SECONDS, expBackOffBound, new DiscoveryClient.CacheRefreshThread()), (long)renewalIntervalInSecs, TimeUnit.SECONDS);
        }

2：服务注册

this.instanceInfoReplicator.start(this.clientConfig.getInitialInstanceInfoReplicationIntervalSeconds());

在这个里面run方法进行了服务注册

具体注册方法：都是rest风格来进行注册

EurekaHttpResponse httpResponse;
    try {
        httpResponse = this.eurekaTransport.registrationClient.register(this.instanceInfo);

httpResponse.getStatusCode() == 204;

3: 注册后续期

int renewalIntervalInSecs = instanceInfo.getLeaseInfo().getRenewalIntervalInSecs();

int renewalIntervalInSecs = DEFAULT_LEASE_RENEWAL_INTERVAL; 30秒去续期

  boolean renew() {
       EurekaHttpResponse<InstanceInfo> httpResponse;
       try {
           httpResponse = eurekaTransport.registrationClient.sendHeartBeat(instanceInfo.getAppName(), instanceInfo.getId(), instanceInfo, null);
   		
   根据实例名字以及实例的id实例信息，去发送心跳

4：服务剔除

最终还是来自：DiscoveryClient

第二个：org.springframework.cloud.client.discovery

下面的DiscoveryClient

这2个的区别在于:

public class EurekaDiscoveryClient implements DiscoveryClient

EurekaDiscoveryClient里面包含了EurekaClient 这个就是netflix自带的EurekaClient

hyoGirl/MyCloud

Eureka

服务发现