如下图,org.springframework.cloud.spring-cloud-commons
包下定义了一系列接口,其中就包括serviceregistry
的系列规范,并通过SPI机制去调用接口实现。
在该包的META-INF/spring.factories
文件中,可以找到EnableAutoConfiguration.class
为key的value中有AutoServiceRegistrationAutoConfiguration.class
这一项。
来看看这个AutoServiceRegistrationAutoConfiguration
配置类:
对应的,在com.alibaba.cloud.nacos
包下(位于spring-cloud-starter-nacos-discovery jar包中)的META-INF/spring.fatories
有个nacos服务注册配置类,如下图:
这个NacosServiceRegistryAutoConfiguration
配置类就定义了上面SpringCloud的AutoServiceRegistration
接口的实现类:
package com.alibaba.cloud.nacos.registry;
...
/**
* @author xiaojing
* @author <a href="mailto:[email protected]">Mercy</a>
*/
@Configuration(proxyBeanMethods = false)
@EnableConfigurationProperties
@ConditionalOnNacosDiscoveryEnabled
@ConditionalOnProperty(value = "spring.cloud.service-registry.auto-registration.enabled",
matchIfMissing = true)
@AutoConfigureAfter({
AutoServiceRegistrationConfiguration.class,
AutoServiceRegistrationAutoConfiguration.class,
NacosDiscoveryAutoConfiguration.class })
public class NacosServiceRegistryAutoConfiguration {
@Bean
public NacosServiceRegistry nacosServiceRegistry(
NacosDiscoveryProperties nacosDiscoveryProperties) {
return new NacosServiceRegistry(nacosDiscoveryProperties);
}
@Bean
@ConditionalOnBean(AutoServiceRegistrationProperties.class)
public NacosRegistration nacosRegistration(
ObjectProvider<List<NacosRegistrationCustomizer>> registrationCustomizers,
NacosDiscoveryProperties nacosDiscoveryProperties,
ApplicationContext context) {
return new NacosRegistration(registrationCustomizers.getIfAvailable(),
nacosDiscoveryProperties, context);
}
/**
** 这里,这个NacosAutoServiceRegistration就是AutoServiceRegistration接口的实现类
**/
@Bean
@ConditionalOnBean(AutoServiceRegistrationProperties.class)
public NacosAutoServiceRegistration nacosAutoServiceRegistration(
NacosServiceRegistry registry,
AutoServiceRegistrationProperties autoServiceRegistrationProperties,
NacosRegistration registration) {
return new NacosAutoServiceRegistration(registry,
autoServiceRegistrationProperties, registration);
}
}
NacosAutoServiceRegistration
中的register()
方法开始注册服务,整个调用流程为:
继续追根溯源,这个registry()
方法是在AbstractAutoServiceRegistration implements ApplicationListener<WebServerInitializedEvent>
类的onApplicationEvent()
方法(onApplicationEvent->bind->start->registey) 。
调用的心跳默认5秒一次,具体可参考BeatReactor
类中的buildBeatInfo()
方法,其中有个beatInfo.setPeriod(instance.getInstanceHeartBeatInterval());
这里获取到一个常量5s。
更加详细的流程可以参考:源码阅读|年轻人可以不讲武德,但是你得会阅读Naocs源码
另外上面最后一步的NamingClientProxy
接口的实现如下,利用到了委托模式(delegate)也叫代理模式?: