nacos官方地址：https://nacos.io/zh-cn/
大家可以看一下nacos的中文手册以及官方源码，博主就不带领大家快速入门 了，官方文档中都有而且非常标准，比其他博客写的好多了并且还是实时更新的。
先看一下博主给大家画的流程图，掌握一下大概的基本流程，好理解，博主给大家讲源码：
https://www.processon.com/view/link/5f7e895be0b34d0711f65178
nacos最主要的功能就是服务注册及发现，那它到底是如何实现的呢？博主用的springboot开发的，所以直接就去找nacos的jar包下的spring.factories，这是每个要自动注入的服务jar的必备文件，我们来看一下
里面有很多的自动配置类，我们只看一下NacosServiceRegistryAutoConfiguration，该类主要做的是服务注册的相关事宜，如果大家第一次看源码的话不知道该如何下手，最笨的方法就是一个一个看。总会找到的，最好要找名字看起来就像自己找的，因为这是阿里巴巴开发的，他们是有java开发规范的，要做到见名知意。
1 /** 2 * @author xiaojing 3 * @author <a href="mailto:mercyblitz@gmail.com">Mercy</a> 4 */ 5 @Configuration(proxyBeanMethods = false) 6 @EnableConfigurationProperties 7 @ConditionalOnNacosDiscoveryEnabled 8 @ConditionalOnProperty(value = "spring.cloud.service-registry.auto-registration.enabled", 9 matchIfMissing = true) 10 @AutoConfigureAfter({ AutoServiceRegistrationConfiguration.class, 11 AutoServiceRegistrationAutoConfiguration.class, 12 NacosDiscoveryAutoConfiguration.class }) 13 public class NacosServiceRegistryAutoConfiguration { 14 15 @Bean 16 public NacosServiceRegistry nacosServiceRegistry( 17 NacosDiscoveryProperties nacosDiscoveryProperties) { 18 return new NacosServiceRegistry(nacosDiscoveryProperties); 19 } 20 21 @Bean 22 @ConditionalOnBean(AutoServiceRegistrationProperties.class) 23 public NacosRegistration nacosRegistration( 24 NacosDiscoveryProperties nacosDiscoveryProperties, 25 ApplicationContext context) { 26 return new NacosRegistration(nacosDiscoveryProperties, context); 27 } 28 29 @Bean 30 @ConditionalOnBean(AutoServiceRegistrationProperties.class) 31 public NacosAutoServiceRegistration nacosAutoServiceRegistration( 32 NacosServiceRegistry registry, 33 AutoServiceRegistrationProperties autoServiceRegistrationProperties, 34 NacosRegistration registration) { 35 //这里才是自动注入的类，我们需要进去看一下 36 return new NacosAutoServiceRegistration(registry, 37 autoServiceRegistrationProperties, registration); 38 } 39 40 }
1 public class NacosAutoServiceRegistration 2 extends AbstractAutoServiceRegistration<Registration> { 3 4 private static final Logger log = LoggerFactory 5 .getLogger(NacosAutoServiceRegistration.class); 6 7 private NacosRegistration registration; 8 9 public NacosAutoServiceRegistration(ServiceRegistry<Registration> serviceRegistry, 10 AutoServiceRegistrationProperties autoServiceRegistrationProperties, 11 NacosRegistration registration) { 12 super(serviceRegistry, autoServiceRegistrationProperties); 13 this.registration = registration; 14 } 15 16 @Deprecated 17 public void setPort(int port) { 18 getPort().set(port); 19 } 20 21 @Override 22 protected NacosRegistration getRegistration() { 23 if (this.registration.getPort() < 0 && this.getPort().get() > 0) { 24 this.registration.setPort(this.getPort().get()); 25 } 26 Assert.isTrue(this.registration.getPort() > 0, "service.port has not been set"); 27 return this.registration; 28 } 29 30 @Override 31 protected NacosRegistration getManagementRegistration() { 32 return null; 33 } 34 35 @Override 36 protected void register() { 37 if (!this.registration.getNacosDiscoveryProperties().isRegisterEnabled()) { 38 log.debug("Registration disabled."); 39 return; 40 } 41 if (this.registration.getPort() < 0) { 42 this.registration.setPort(getPort().get()); 43 } 44 super.register(); 45 } 46 47 @Override 48 protected void registerManagement() { 49 if (!this.registration.getNacosDiscoveryProperties().isRegisterEnabled()) { 50 return; 51 } 52 super.registerManagement(); 53 54 } 55 56 @Override 57 protected Object getConfiguration() { 58 return this.registration.getNacosDiscoveryProperties(); 59 } 60 61 @Override 62 protected boolean isEnabled() { 63 return this.registration.getNacosDiscoveryProperties().isRegisterEnabled(); 64 } 65 66 @Override 67 @SuppressWarnings("deprecation") 68 protected String getAppName() { 69 String appName = registration.getNacosDiscoveryProperties().getService(); 70 return StringUtils.isEmpty(appName) ? super.getAppName() : appName; 71 } 72 73 }
看到这里，大家可能有点懵，我应该找那个方法呢？大家可以看一下构造器中，引用了父类，当我们看到父类的时候，发现父类实现了ApplicationListener，这个类大家不陌生，系统会自动执行其onApplicationEvent而正好我们的类实现了这个方法，最后我们发现了应该看register() 方法，大家可以来看看这个方法的实现
1 @Override 2 public void register(Registration registration) { 3 4 if (StringUtils.isEmpty(registration.getServiceId())) { 5 log.warn("No service to register for nacos client..."); 6 return; 7 } 8 //看到这两个参数，大家看过nacos文档就知道这两个参数要干啥用了 9 String serviceId = registration.getServiceId(); 10 String group = nacosDiscoveryProperties.getGroup(); 11 //要发送的实例对象，具体的属性，大家可以看看这个方法 12 Instance instance = getNacosInstanceFromRegistration(registration); 13 14 try { 15 //走这里，是真正的注册服务 16 namingService.registerInstance(serviceId, group, instance); 17 log.info("nacos registry, {} {} {}:{} register finished", group, serviceId, 18 instance.getIp(), instance.getPort()); 19 } 20 catch (Exception e) { 21 log.error("nacos registry, {} register failed...{},", serviceId, 22 registration.toString(), e); 23 // rethrow a RuntimeException if the registration is failed. 24 // issue : https://github.com/alibaba/spring-cloud-alibaba/issues/1132 25 rethrowRuntimeException(e); 26 } 27 }
1 @Override 2 public void registerInstance(String serviceName, String groupName, Instance instance) throws NacosException { 3 //是否是临时的，这个参数默认是临时实例，这个是临时或者是否持久很重要，先记住 4 if (instance.isEphemeral()) { 5 //填写各种心跳信息，毕竟服务需要往nacos发送心跳，nacos才能知道该服务是否还存活 6 BeatInfo beatInfo = new BeatInfo(); 7 beatInfo.setServiceName(NamingUtils.getGroupedName(serviceName, groupName)); 8 beatInfo.setIp(instance.getIp()); 9 beatInfo.setPort(instance.getPort()); 10 beatInfo.setCluster(instance.getClusterName()); 11 beatInfo.setWeight(instance.getWeight()); 12 beatInfo.setMetadata(instance.getMetadata()); 13 beatInfo.setScheduled(false); 14 beatInfo.setPeriod(instance.getInstanceHeartBeatInterval()); 15 //看一下客服端是如何发送心跳 16 beatReactor.addBeatInfo(NamingUtils.getGroupedName(serviceName, groupName), beatInfo); 17 } 18 //注册服务 19 serverProxy.registerService(NamingUtils.getGroupedName(serviceName, groupName), groupName, instance); 20 }
1 @Override 2 public void run() { 3 if (beatInfo.isStopped()) { 4 return; 5 } 6 long nextTime = beatInfo.getPeriod(); 7 try { 8 //会调用nacos服务端的/instance/beat接口 9 JSONObject result = serverProxy.sendBeat(beatInfo, BeatReactor.this.lightBeatEnabled); 10 long interval = result.getIntValue("clientBeatInterval"); 11 boolean lightBeatEnabled = false; 12 if (result.containsKey(CommonParams.LIGHT_BEAT_ENABLED)) { 13 lightBeatEnabled = result.getBooleanValue(CommonParams.LIGHT_BEAT_ENABLED); 14 } 15 BeatReactor.this.lightBeatEnabled = lightBeatEnabled; 16 if (interval > 0) { 17 nextTime = interval; 18 } 19 int code = NamingResponseCode.OK; 20 if (result.containsKey(CommonParams.CODE)) { 21 code = result.getIntValue(CommonParams.CODE); 22 } 23 //如果找不到服务，则进行注册服务 24 if (code == NamingResponseCode.RESOURCE_NOT_FOUND) { 25 Instance instance = new Instance(); 26 instance.setPort(beatInfo.getPort()); 27 instance.setIp(beatInfo.getIp()); 28 instance.setWeight(beatInfo.getWeight()); 29 instance.setMetadata(beatInfo.getMetadata()); 30 instance.setClusterName(beatInfo.getCluster()); 31 instance.setServiceName(beatInfo.getServiceName()); 32 instance.setInstanceId(instance.getInstanceId()); 33 instance.setEphemeral(true); 34 try { 35 //该方法封装好参数后，会调用/instance接口 36 serverProxy.registerService(beatInfo.getServiceName(), 37 NamingUtils.getGroupName(beatInfo.getServiceName()), instance); 38 } catch (Exception ignore) { 39 } 40 } 41 } catch (NacosException ne) { 42 NAMING_LOGGER.error("[CLIENT-BEAT] failed to send beat: {}, code: {}, msg: {}", 43 JSON.toJSONString(beatInfo), ne.getErrCode(), ne.getErrMsg()); 44 45 } 46 //定时线程池不会一直循环进行调用，所以每次执行完之后会继续添加定时任务进行发送心跳 47 executorService.schedule(new BeatTask(beatInfo), nextTime, TimeUnit.MILLISECONDS); 48 }
看完发送心跳的方法，我们该看注册服务的方法了：serverProxy.registerService(NamingUtils.getGroupedName(serviceName, groupName), groupName, instance);其实就是发送心跳后，找不到服务时调用的/instance接口。
到此，我们的服务就会注册到nacos服务端中，客户端的代码就是如此，还是挺简单的，我们下一篇就会带大家走进服务端的代码。