聊聊NacosDiscoveryEndpointsAutoConfiguration

序

本文主要研究一下NacosDiscoveryEndpointsAutoConfiguration

NacosDiscoveryEndpointsAutoConfiguration

nacos-spring-boot-project/nacos-discovery-spring-boot-actuator/src/main/java/com/alibaba/boot/nacos/discovery/actuate/autoconfigure/NacosDiscoveryEndpointsAutoConfiguration.java

@Configuration
public class NacosDiscoveryEndpointsAutoConfiguration {

    @Bean
    @ConditionalOnMissingBean
    @ConditionalOnEnabledEndpoint
    public NacosDiscoveryEndpoint nacosDiscoveryEndpoint() {
        return new NacosDiscoveryEndpoint();
    }

}

• NacosDiscoveryEndpointsAutoConfiguration注册了NacosDiscoveryEndpoint

NacosDiscoveryEndpoint

nacos-spring-boot-project/nacos-discovery-spring-boot-actuator/src/main/java/com/alibaba/boot/nacos/discovery/actuate/endpoint/NacosDiscoveryEndpoint.java

@Endpoint(id = NacosDiscoveryConstants.ENDPOINT_PREFIX)
public class NacosDiscoveryEndpoint {

    @Autowired
    private ApplicationContext applicationContext;

    private static final Integer PAGE_SIZE = 100;

    @ReadOperation
    public Map<String, Object> invoke() {
        Map<String, Object> result = new HashMap<>();

        result.put("nacosDiscoveryGlobalProperties",
                PropertiesUtils.extractSafeProperties(applicationContext.getBean(
                        DISCOVERY_GLOBAL_NACOS_PROPERTIES_BEAN_NAME, Properties.class)));

        NacosServiceFactory nacosServiceFactory = CacheableEventPublishingNacosServiceFactory.getSingleton();

        JSONArray array = new JSONArray();
        for (NamingService namingService : nacosServiceFactory.getNamingServices()) {
            JSONObject jsonObject = new JSONObject();
            try {
                jsonObject.put("servicesOfServer",
                        namingService.getServicesOfServer(0, PAGE_SIZE));
                jsonObject.put("subscribeServices", namingService.getSubscribeServices());
                array.add(jsonObject);
            }
            catch (Exception e) {
                jsonObject.put("serverStatus", namingService.getServerStatus() + ": "
                         + NacosUtils.SEPARATOR + e.getMessage());
            }
        }

        result.put("namingServersStatus", array);
        return result;
    }

}

• NacosDiscoveryEndpoint提供了一个ReadOperation，它返回的map里头会有nacosDiscoveryGlobalProperties及namingServersStatus；namingServersStatus是个JSONArray，每个JSONArray的元素是个JSONObject，JSONObject有servicesOfServer、subscribeServices；其中servicesOfServer通过namingService.getServicesOfServer(0, PAGE_SIZE)获取，PAGE_SIZE为100

NacosDiscoveryBeanDefinitionRegistrar

nacos-spring-context-0.3.3-sources.jar!/com/alibaba/nacos/spring/context/annotation/discovery/NacosDiscoveryBeanDefinitionRegistrar.java

public class NacosDiscoveryBeanDefinitionRegistrar implements ImportBeanDefinitionRegistrar, EnvironmentAware {

    private Environment environment;

    @Override
    public void registerBeanDefinitions(AnnotationMetadata importingClassMetadata, BeanDefinitionRegistry registry) {
        AnnotationAttributes attributes = AnnotationAttributes.fromMap(
                importingClassMetadata.getAnnotationAttributes(EnableNacosDiscovery.class.getName()));
        // Register Global Nacos Properties Bean
        registerGlobalNacosProperties(attributes, registry, environment, DISCOVERY_GLOBAL_NACOS_PROPERTIES_BEAN_NAME);
        // Register Nacos Common Beans
        registerNacosCommonBeans(registry);
        // Register Nacos Discovery Beans
        registerNacosDiscoveryBeans(registry);
    }

    @Override
    public void setEnvironment(Environment environment) {
        this.environment = environment;
    }
}

• NacosDiscoveryBeanDefinitionRegistrar实现了ImportBeanDefinitionRegistrar, EnvironmentAware接口，其registerBeanDefinitions从importingClassMetadata获取EnableNacosDiscovery的attributes，然后通过registerGlobalNacosProperties方法注册DISCOVERY_GLOBAL_NACOS_PROPERTIES_BEAN_NAME

NacosBeanUtils

nacos-spring-context-0.3.3-sources.jar!/com/alibaba/nacos/spring/util/NacosBeanUtils.java

public abstract class NacosBeanUtils {

    //......

    public static void registerGlobalNacosProperties(AnnotationAttributes attributes,
                                                     BeanDefinitionRegistry registry,
                                                     PropertyResolver propertyResolver,
                                                     String beanName) {
        if (attributes == null) {
            return; // Compatible with null
        }
        AnnotationAttributes globalPropertiesAttributes = attributes.getAnnotation("globalProperties");
        registerGlobalNacosProperties((Map<?, ?>) globalPropertiesAttributes, registry, propertyResolver,
                beanName);
    }

    public static void registerGlobalNacosProperties(Map<?, ?> globalPropertiesAttributes,
                                                     BeanDefinitionRegistry registry,
                                                     PropertyResolver propertyResolver,
                                                     String beanName) {
        Properties globalProperties = resolveProperties(globalPropertiesAttributes, propertyResolver);
        registerSingleton(registry, beanName, globalProperties);
    }

    public static void registerSingleton(BeanDefinitionRegistry registry, String beanName, Object singletonObject) {
        SingletonBeanRegistry beanRegistry = null;
        if (registry instanceof SingletonBeanRegistry) {
            beanRegistry = (SingletonBeanRegistry) registry;
        } else if (registry instanceof AbstractApplicationContext) {
            // Maybe AbstractApplicationContext or its sub-classes
            beanRegistry = ((AbstractApplicationContext) registry).getBeanFactory();
        }
        // Register Singleton Object if possible
        if (beanRegistry != null) {
            // Determine in advance whether injected with beans
            if (!beanRegistry.containsSingleton(beanName)) {
                beanRegistry.registerSingleton(beanName, singletonObject);
            }
        }
    }

    //......
}

• NacosBeanUtils的registerGlobalNacosProperties方法从AnnotationAttributes获取globalProperties的AnnotationAttributes，然后通过registerGlobalNacosProperties解析AnnotationAttributes的属性，最后registerSingleton

小结

NacosDiscoveryEndpointsAutoConfiguration注册了NacosDiscoveryEndpoint；NacosDiscoveryEndpoint提供了一个ReadOperation，它返回的map里头会有nacosDiscoveryGlobalProperties及namingServersStatus；namingServersStatus是个JSONArray，每个JSONArray的元素是个JSONObject，JSONObject有servicesOfServer、subscribeServices；其中servicesOfServer通过namingService.getServicesOfServer(0, PAGE_SIZE)获取，PAGE_SIZE为100

doc

• NacosDiscoveryEndpointsAutoConfiguration