获取注册表中服务实例信息
需要注意的是，Eureka Server同时也是一个Eureka Client，在不禁止Eureka Server的客户端行为时，它会向它配置文件中的其他Eureka Server进行拉取注册表、服务注册和发送心跳等操作
启动server注册相关bean注册外部的配置类 spring-cloud-netflix-eureka-server-2.1.2.REALEASE.jar 中 META-INF/spring.factories中
org.springframework.boot.autoconfigure.EnableAutoConfiguration=\
org.springframework.cloud.netflix.eureka.server.EurekaServerAutoConfiguration
启动时会自动加载：EurekaServerAutoConfiguration功能：向spring的bean工厂添加eureka-server相关功能的bean
// // Source code recreated from a .class file by IntelliJ IDEA // (powered by FernFlower decompiler) // package org.springframework.cloud.netflix.eureka.server; import com.netflix.appinfo.ApplicationInfoManager; import com.netflix.discovery.EurekaClient; import com.netflix.discovery.EurekaClientConfig; import com.netflix.discovery.converters.EurekaJacksonCodec; import com.netflix.discovery.converters.wrappers.CodecWrapper; import com.netflix.discovery.converters.wrappers.CodecWrappers; import com.netflix.discovery.converters.wrappers.CodecWrappers.JacksonJsonMini; import com.netflix.discovery.converters.wrappers.CodecWrappers.JacksonXmlMini; import com.netflix.discovery.converters.wrappers.CodecWrappers.XStreamXml; import com.netflix.eureka.DefaultEurekaServerContext; import com.netflix.eureka.EurekaServerConfig; import com.netflix.eureka.EurekaServerContext; import com.netflix.eureka.cluster.PeerEurekaNode; import com.netflix.eureka.cluster.PeerEurekaNodes; import com.netflix.eureka.registry.PeerAwareInstanceRegistry; import com.netflix.eureka.resources.DefaultServerCodecs; import com.netflix.eureka.resources.ServerCodecs; import com.netflix.eureka.transport.JerseyReplicationClient; import com.sun.jersey.api.core.DefaultResourceConfig; import com.sun.jersey.spi.container.servlet.ServletContainer; import java.util.Collections; import java.util.HashMap; import java.util.HashSet; import java.util.Iterator; import java.util.Map; import java.util.Set; import javax.servlet.Filter; import javax.ws.rs.Path; import javax.ws.rs.core.Application; import javax.ws.rs.ext.Provider; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.beans.factory.annotation.Qualifier; import org.springframework.beans.factory.config.BeanDefinition; import org.springframework.boot.autoconfigure.condition.ConditionalOnBean; import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean; import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty; import org.springframework.boot.context.properties.EnableConfigurationProperties; import org.springframework.boot.web.servlet.FilterRegistrationBean; import org.springframework.cloud.client.actuator.HasFeatures; import org.springframework.cloud.context.environment.EnvironmentChangeEvent; import org.springframework.cloud.netflix.eureka.server.EurekaServerMarkerConfiguration.Marker; import org.springframework.context.ApplicationListener; import org.springframework.context.annotation.Bean; import org.springframework.context.annotation.ClassPathScanningCandidateComponentProvider; import org.springframework.context.annotation.Configuration; import org.springframework.context.annotation.Import; import org.springframework.context.annotation.PropertySource; import org.springframework.core.env.Environment; import org.springframework.core.io.ResourceLoader; import org.springframework.core.type.filter.AnnotationTypeFilter; import org.springframework.util.ClassUtils; import org.springframework.web.servlet.config.annotation.WebMvcConfigurer; @Configuration( proxyBeanMethods = false ) @Import({EurekaServerInitializerConfiguration.class}) @ConditionalOnBean({Marker.class}) @EnableConfigurationProperties({EurekaDashboardProperties.class, InstanceRegistryProperties.class}) @PropertySource({"classpath:/eureka/server.properties"}) public class EurekaServerAutoConfiguration implements WebMvcConfigurer { private static final String[] EUREKA_PACKAGES = new String[]{"com.netflix.discovery", "com.netflix.eureka"}; @Autowired private ApplicationInfoManager applicationInfoManager; @Autowired private EurekaServerConfig eurekaServerConfig; @Autowired private EurekaClientConfig eurekaClientConfig; @Autowired private EurekaClient eurekaClient; @Autowired private InstanceRegistryProperties instanceRegistryProperties; public static final CloudJacksonJson JACKSON_JSON = new CloudJacksonJson(); public EurekaServerAutoConfiguration() { } @Bean public HasFeatures eurekaServerFeature() { return HasFeatures.namedFeature("Eureka Server", EurekaServerAutoConfiguration.class); } @Bean @ConditionalOnProperty( prefix = "eureka.dashboard", name = {"enabled"}, matchIfMissing = true ) public EurekaController eurekaController() { return new EurekaController(this.applicationInfoManager); } @Bean public ServerCodecs serverCodecs() { return new EurekaServerAutoConfiguration.CloudServerCodecs(this.eurekaServerConfig); } private static CodecWrapper getFullJson(EurekaServerConfig serverConfig) { CodecWrapper codec = CodecWrappers.getCodec(serverConfig.getJsonCodecName()); return codec == null ? CodecWrappers.getCodec(JACKSON_JSON.codecName()) : codec; } private static CodecWrapper getFullXml(EurekaServerConfig serverConfig) { CodecWrapper codec = CodecWrappers.getCodec(serverConfig.getXmlCodecName()); return codec == null ? CodecWrappers.getCodec(XStreamXml.class) : codec; } @Bean @ConditionalOnMissingBean public ReplicationClientAdditionalFilters replicationClientAdditionalFilters() { return new ReplicationClientAdditionalFilters(Collections.emptySet()); } @Bean public PeerAwareInstanceRegistry peerAwareInstanceRegistry(ServerCodecs serverCodecs) { this.eurekaClient.getApplications(); return new InstanceRegistry(this.eurekaServerConfig, this.eurekaClientConfig, serverCodecs, this.eurekaClient, this.instanceRegistryProperties.getExpectedNumberOfClientsSendingRenews(), this.instanceRegistryProperties.getDefaultOpenForTrafficCount()); } @Bean @ConditionalOnMissingBean public PeerEurekaNodes peerEurekaNodes(PeerAwareInstanceRegistry registry, ServerCodecs serverCodecs, ReplicationClientAdditionalFilters replicationClientAdditionalFilters) { return new EurekaServerAutoConfiguration.RefreshablePeerEurekaNodes(registry, this.eurekaServerConfig, this.eurekaClientConfig, serverCodecs, this.applicationInfoManager, replicationClientAdditionalFilters); } @Bean @ConditionalOnMissingBean public EurekaServerContext eurekaServerContext(ServerCodecs serverCodecs, PeerAwareInstanceRegistry registry, PeerEurekaNodes peerEurekaNodes) { return new DefaultEurekaServerContext(this.eurekaServerConfig, serverCodecs, registry, peerEurekaNodes, this.applicationInfoManager); } @Bean public EurekaServerBootstrap eurekaServerBootstrap(PeerAwareInstanceRegistry registry, EurekaServerContext serverContext) { return new EurekaServerBootstrap(this.applicationInfoManager, this.eurekaClientConfig, this.eurekaServerConfig, registry, serverContext); } @Bean public FilterRegistrationBean<?> jerseyFilterRegistration(Application eurekaJerseyApp) { FilterRegistrationBean<Filter> bean = new FilterRegistrationBean(); bean.setFilter(new ServletContainer(eurekaJerseyApp)); bean.setOrder(2147483647); bean.setUrlPatterns(Collections.singletonList("/eureka/*")); return bean; } @Bean public Application jerseyApplication(Environment environment, ResourceLoader resourceLoader) { ClassPathScanningCandidateComponentProvider provider = new ClassPathScanningCandidateComponentProvider(false, environment); provider.addIncludeFilter(new AnnotationTypeFilter(Path.class)); provider.addIncludeFilter(new AnnotationTypeFilter(Provider.class)); Set<Class<?>> classes = new HashSet(); String[] var5 = EUREKA_PACKAGES; int var6 = var5.length; for(int var7 = 0; var7 < var6; ++var7) { String basePackage = var5[var7]; Set<BeanDefinition> beans = provider.findCandidateComponents(basePackage); Iterator var10 = beans.iterator(); while(var10.hasNext()) { BeanDefinition bd = (BeanDefinition)var10.next(); Class<?> cls = ClassUtils.resolveClassName(bd.getBeanClassName(), resourceLoader.getClassLoader()); classes.add(cls); } } Map<String, Object> propsAndFeatures = new HashMap(); propsAndFeatures.put("com.sun.jersey.config.property.WebPageContentRegex", "/eureka/(fonts|images|css|js)/.*"); DefaultResourceConfig rc = new DefaultResourceConfig(classes); rc.setPropertiesAndFeatures(propsAndFeatures); return rc; } @Bean @ConditionalOnBean( name = {"httpTraceFilter"} ) public FilterRegistrationBean<?> traceFilterRegistration(@Qualifier("httpTraceFilter") Filter filter) { FilterRegistrationBean<Filter> bean = new FilterRegistrationBean(); bean.setFilter(filter); bean.setOrder(2147483637); return bean; } static { CodecWrappers.registerWrapper(JACKSON_JSON); EurekaJacksonCodec.setInstance(JACKSON_JSON.getCodec()); } class CloudServerCodecs extends DefaultServerCodecs { CloudServerCodecs(EurekaServerConfig serverConfig) { super(EurekaServerAutoConfiguration.getFullJson(serverConfig), CodecWrappers.getCodec(JacksonJsonMini.class), EurekaServerAutoConfiguration.getFullXml(serverConfig), CodecWrappers.getCodec(JacksonXmlMini.class)); } } static class RefreshablePeerEurekaNodes extends PeerEurekaNodes implements ApplicationListener<EnvironmentChangeEvent> { private ReplicationClientAdditionalFilters replicationClientAdditionalFilters; RefreshablePeerEurekaNodes(final PeerAwareInstanceRegistry registry, final EurekaServerConfig serverConfig, final EurekaClientConfig clientConfig, final ServerCodecs serverCodecs, final ApplicationInfoManager applicationInfoManager, final ReplicationClientAdditionalFilters replicationClientAdditionalFilters) { super(registry, serverConfig, clientConfig, serverCodecs, applicationInfoManager); this.replicationClientAdditionalFilters = replicationClientAdditionalFilters; } protected PeerEurekaNode createPeerEurekaNode(String peerEurekaNodeUrl) { JerseyReplicationClient replicationClient = JerseyReplicationClient.createReplicationClient(this.serverConfig, this.serverCodecs, peerEurekaNodeUrl); this.replicationClientAdditionalFilters.getFilters().forEach(replicationClient::addReplicationClientFilter); String targetHost = hostFromUrl(peerEurekaNodeUrl); if (targetHost == null) { targetHost = "host"; } return new PeerEurekaNode(this.registry, targetHost, peerEurekaNodeUrl, replicationClient, this.serverConfig); } public void onApplicationEvent(final EnvironmentChangeEvent event) { if (this.shouldUpdate(event.getKeys())) { this.updatePeerEurekaNodes(this.resolvePeerUrls()); } } protected boolean shouldUpdate(final Set<String> changedKeys) { assert changedKeys != null; if (this.clientConfig.shouldUseDnsForFetchingServiceUrls()) { return false; } else if (changedKeys.contains("eureka.client.region")) { return true; } else { Iterator var2 = changedKeys.iterator(); String key; do { if (!var2.hasNext()) { return false; } key = (String)var2.next(); } while(!key.startsWith("eureka.client.service-url.") && !key.startsWith("eureka.client.availability-zones.")); return true; } } } @Configuration( proxyBeanMethods = false ) protected static class EurekaServerConfigBeanConfiguration { protected EurekaServerConfigBeanConfiguration() { } @Bean @ConditionalOnMissingBean public EurekaServerConfig eurekaServerConfig(EurekaClientConfig clientConfig) { EurekaServerConfigBean server = new EurekaServerConfigBean(); if (clientConfig.shouldRegisterWithEureka()) { server.setRegistrySyncRetries(5); } return server; } } }