Nacos（一）源码分析Nacos注册示例流程

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。

---