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。
/**
* @author xiaojing
* @author <a rel="nofollow" href="mailto:mercyblitz@gmail.com">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(
NacosDiscoveryProperties nacosDiscoveryProperties,
ApplicationContext context) {
return new NacosRegistration(nacosDiscoveryProperties, context);
}
@Bean
@ConditionalOnBean(AutoServiceRegistrationProperties.class)
public NacosAutoServiceRegistration nacosAutoServiceRegistration(
NacosServiceRegistry registry,
AutoServiceRegistrationProperties autoServiceRegistrationProperties,
NacosRegistration registration) {
//这里才是自动注入的类，我们需要进去看一下
return new NacosAutoServiceRegistration(registry,
autoServiceRegistrationProperties, registration);
}
}
public class NacosAutoServiceRegistration
extends AbstractAutoServiceRegistration<Registration> {
private static final Logger log = LoggerFactory
.getLogger(NacosAutoServiceRegistration.class);
private NacosRegistration registration;
public NacosAutoServiceRegistration(ServiceRegistry<Registration> serviceRegistry,
AutoServiceRegistrationProperties autoServiceRegistrationProperties,
NacosRegistration registration) {
super(serviceRegistry, autoServiceRegistrationProperties);
this.registration = registration;
}
@Deprecated
public void setPort(int port) {
getPort().set(port);
}
@Override
protected NacosRegistration getRegistration() {
if (this.registration.getPort() < 0 && this.getPort().get() > 0) {
this.registration.setPort(this.getPort().get());
}
Assert.isTrue(this.registration.getPort() > 0, "service.port has not been set");
return this.registration;
}
@Override
protected NacosRegistration getManagementRegistration() {
return null;
}
@Override
protected void register() {
if (!this.registration.getNacosDiscoveryProperties().isRegisterEnabled()) {
log.debug("Registration disabled.");
return;
}
if (this.registration.getPort() < 0) {
this.registration.setPort(getPort().get());
}
super.register();
}
@Override
protected void registerManagement() {
if (!this.registration.getNacosDiscoveryProperties().isRegisterEnabled()) {
return;
}
super.registerManagement();
}
@Override
protected Object getConfiguration() {
return this.registration.getNacosDiscoveryProperties();
}
@Override
protected boolean isEnabled() {
return this.registration.getNacosDiscoveryProperties().isRegisterEnabled();
}
@Override
@SuppressWarnings("deprecation")
protected String getAppName() {
String appName = registration.getNacosDiscoveryProperties().getService();
return StringUtils.isEmpty(appName) ? super.getAppName() : appName;
}
}
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
@Override
public void register(Registration registration) {
if (StringUtils.isEmpty(registration.getServiceId())) {
log.warn("No service to register for nacos client...");
return;
}
//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
String serviceId = registration.getServiceId();
String group = nacosDiscoveryProperties.getGroup();
//要发送的实例对象，具体的属性，大家可以看看这个方法
Instance instance = getNacosInstanceFromRegistration(registration);
try {
//走这里，是真正的注册服务
namingService.registerInstance(serviceId, group, instance);
log.info("nacos registry, {} {} {}:{} register finished", group, serviceId,
instance.getIp(), instance.getPort());
}
catch (Exception e) {
log.error("nacos registry, {} register failed...{},", serviceId,
registration.toString(), e);
// rethrow a RuntimeException if the registration is failed.
// issue : https://github.com/alibaba/spring-cloud-alibaba/issues/1132
rethrowRuntimeException(e);
}
}
@Override
public void registerInstance(String serviceName, String groupName, Instance instance) throws NacosException {
//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
if (instance.isEphemeral()) {
//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
BeatInfo beatInfo = new BeatInfo();
beatInfo.setServiceName(NamingUtils.getGroupedName(serviceName, groupName));
beatInfo.setIp(instance.getIp());
beatInfo.setPort(instance.getPort());
beatInfo.setCluster(instance.getClusterName());
beatInfo.setWeight(instance.getWeight());
beatInfo.setMetadata(instance.getMetadata());
beatInfo.setScheduled(false);
beatInfo.setPeriod(instance.getInstanceHeartBeatInterval());
//看一下客服端是如何发送心跳
beatReactor.addBeatInfo(NamingUtils.getGroupedName(serviceName, groupName), beatInfo);
}
//注册服务
serverProxy.registerService(NamingUtils.getGroupedName(serviceName, groupName), groupName, instance);
}
@Override
public void registerInstance(String serviceName, String groupName, Instance instance) throws NacosException {
//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
if (instance.isEphemeral()) {
//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
BeatInfo beatInfo = new BeatInfo();
beatInfo.setServiceName(NamingUtils.getGroupedName(serviceName, groupName));
beatInfo.setIp(instance.getIp());
beatInfo.setPort(instance.getPort());
beatInfo.setCluster(instance.getClusterName());
beatInfo.setWeight(instance.getWeight());
beatInfo.setMetadata(instance.getMetadata());
beatInfo.setScheduled(false);
beatInfo.setPeriod(instance.getInstanceHeartBeatInterval());
//看一下客服端是如何发送心跳
beatReactor.addBeatInfo(NamingUtils.getGroupedName(serviceName, groupName), beatInfo);
}
//注册服务
serverProxy.registerService(NamingUtils.getGroupedName(serviceName, groupName), groupName, instance);
}
@Override
public void run() {
if (beatInfo.isStopped()) {
return;
}
long nextTime = beatInfo.getPeriod();
try {
//会调用nacos服务端的/instance/beat接口
JSONObject result = serverProxy.sendBeat(beatInfo, BeatReactor.this.lightBeatEnabled);
long interval = result.getIntValue("clientBeatInterval");
boolean lightBeatEnabled = false;
if (result.containsKey(CommonParams.LIGHT_BEAT_ENABLED)) {
lightBeatEnabled = result.getBooleanValue(CommonParams.LIGHT_BEAT_ENABLED);
}
BeatReactor.this.lightBeatEnabled = lightBeatEnabled;
if (interval > 0) {
nextTime = interval;
}
int code = NamingResponseCode.OK;
if (result.containsKey(CommonParams.CODE)) {
code = result.getIntValue(CommonParams.CODE);
}
//如果找不到服务，则进行注册服务
if (code == NamingResponseCode.RESOURCE_NOT_FOUND) {
Instance instance = new Instance();
instance.setPort(beatInfo.getPort());
instance.setIp(beatInfo.getIp());
instance.setWeight(beatInfo.getWeight());
instance.setMetadata(beatInfo.getMetadata());
instance.setClusterName(beatInfo.getCluster());
instance.setServiceName(beatInfo.getServiceName());
instance.setInstanceId(instance.getInstanceId());
instance.setEphemeral(true);
try {
//该方法封装好参数后，会调用/instance接口
serverProxy.registerService(beatInfo.getServiceName(),
NamingUtils.getGroupName(beatInfo.getServiceName()), instance);
} catch (Exception ignore) {
}
}
} catch (NacosException ne) {
NAMING_LOGGER.error("[CLIENT-BEAT] failed to send beat: {}, code: {}, msg: {}",
JSON.toJSONString(beatInfo), ne.getErrCode(), ne.getErrMsg());
}
//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
executorService.schedule(new BeatTask(beatInfo), nextTime, TimeUnit.MILLISECONDS);
}
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。
