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spring-cloud-alibaba-nacos配置中心源码阅读

作者：盐析白兔 | 2024-04-20 16:34:56

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spring-cloud-alibaba-nacos配置中心源码阅读

一、前言

spring-cloud-alibaba客户端版本：2.2.1.RELEASE
nacos服务端版本：2.0.4

客户端主动获取配置源码

客户端

入口

通过springboot spi机制加载spring.factories文件配置的类
NacosConfigBootstrapConfiguration,PropertySourceBootstrapConfiguration

org.springframework.cloud.bootstrap.BootstrapConfiguration=\
com.alibaba.cloud.nacos.NacosConfigBootstrapConfiguration
org.springframework.boot.autoconfigure.EnableAutoConfiguration=\
com.alibaba.cloud.nacos.NacosConfigAutoConfiguration,\
com.alibaba.cloud.nacos.endpoint.NacosConfigEndpointAutoConfiguration
org.springframework.boot.diagnostics.FailureAnalyzer=\
com.alibaba.cloud.nacos.diagnostics.analyzer.NacosConnectionFailureAnalyzer

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NacosConfigBootstrapConfiguration

@Configuration(proxyBeanMethods = false)
@ConditionalOnProperty(name = "spring.cloud.nacos.config.enabled", matchIfMissing = true)
public class NacosConfigBootstrapConfiguration {

	@Bean
	@ConditionalOnMissingBean
	public NacosConfigProperties nacosConfigProperties() {
		return new NacosConfigProperties();
	}

	@Bean
	@ConditionalOnMissingBean
	public NacosConfigManager nacosConfigManager(
			NacosConfigProperties nacosConfigProperties) {
		return new NacosConfigManager(nacosConfigProperties);
	}
	
	//加载nacos配置的
	@Bean
	public NacosPropertySourceLocator nacosPropertySourceLocator(
			NacosConfigManager nacosConfigManager) {
		return new NacosPropertySourceLocator(nacosConfigManager);
	}

}


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# AutoConfiguration
org.springframework.boot.autoconfigure.EnableAutoConfiguration=\
org.springframework.cloud.autoconfigure.ConfigurationPropertiesRebinderAutoConfiguration,\
org.springframework.cloud.autoconfigure.LifecycleMvcEndpointAutoConfiguration,\
org.springframework.cloud.autoconfigure.RefreshAutoConfiguration,\
org.springframework.cloud.autoconfigure.RefreshEndpointAutoConfiguration,\
org.springframework.cloud.autoconfigure.WritableEnvironmentEndpointAutoConfiguration
# Application Listeners
org.springframework.context.ApplicationListener=\
org.springframework.cloud.bootstrap.BootstrapApplicationListener,\
org.springframework.cloud.bootstrap.LoggingSystemShutdownListener,\
org.springframework.cloud.context.restart.RestartListener
# Bootstrap components
org.springframework.cloud.bootstrap.BootstrapConfiguration=\
org.springframework.cloud.bootstrap.config.PropertySourceBootstrapConfiguration,\
org.springframework.cloud.bootstrap.encrypt.EncryptionBootstrapConfiguration,\
org.springframework.cloud.autoconfigure.ConfigurationPropertiesRebinderAutoConfiguration,\
org.springframework.boot.autoconfigure.context.PropertyPlaceholderAutoConfiguration

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PropertySourceBootstrapConfiguration 实现了springboot初始化器 当spring ioc启动就会调用 initialize方法

@Override
	public void initialize(ConfigurableApplicationContext applicationContext) {
		List<PropertySource<?>> composite = new ArrayList<>();
		AnnotationAwareOrderComparator.sort(this.propertySourceLocators);
		boolean empty = true;
		ConfigurableEnvironment environment = applicationContext.getEnvironment();
		for (PropertySourceLocator locator : this.propertySourceLocators) {
		//回调所有实现PropertySourceLocator接口实例的locate方法，
			Collection<PropertySource<?>> source = locator.locateCollection(environment);
			if (source == null || source.size() == 0) {
				continue;
			}
			List<PropertySource<?>> sourceList = new ArrayList<>();
			for (PropertySource<?> p : source) {
				sourceList.add(new BootstrapPropertySource<>(p));
			}
			logger.info("Located property source: " + sourceList);
			composite.addAll(sourceList);
			empty = false;
		}
		if (!empty) {
			MutablePropertySources propertySources = environment.getPropertySources();
			String logConfig = environment.resolvePlaceholders("${logging.config:}");
			LogFile logFile = LogFile.get(environment);
			for (PropertySource<?> p : environment.getPropertySources()) {
				if (p.getName().startsWith(BOOTSTRAP_PROPERTY_SOURCE_NAME)) {
					propertySources.remove(p.getName());
				}
			}
			insertPropertySources(propertySources, composite);
			reinitializeLoggingSystem(environment, logConfig, logFile);
			setLogLevels(applicationContext, environment);
			handleIncludedProfiles(environment);
		}
	}

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PropertySourceLoader.locateCollection
这个方法会调用子类的locate方法，来获得一个PropertySource，然后将PropertySource集合返回。接
着它会调用 ConfigServicePropertySourceLocator 的locate方法。

static Collection<PropertySource<?>> locateCollection(PropertySourceLocator locator,
			Environment environment) {
		PropertySource<?> propertySource = locator.locate(environment);
		if (propertySource == null) {
			return Collections.emptyList();
		}
		if (CompositePropertySource.class.isInstance(propertySource)) {
			Collection<PropertySource<?>> sources = ((CompositePropertySource) propertySource)
					.getPropertySources();
			List<PropertySource<?>> filteredSources = new ArrayList<>();
			for (PropertySource<?> p : sources) {
				if (p != null) {
					filteredSources.add(p);
				}
			}
			return filteredSources;
		}
		else {
			return Arrays.asList(propertySource);
		}
	}

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NacosPropertySourceLocator.locate
这个就是Nacos 配置中心加载的的关键实现了，分别调用三个方法来加载配置

NAOCOS配置加载顺序：共享配置 --> 扩展配置 --> 自身配置（后面优先级高）

@Override
	public PropertySource<?> locate(Environment env) {
		nacosConfigProperties.setEnvironment(env);
		ConfigService configService = nacosConfigManager.getConfigService();

		if (null == configService) {
			log.warn("no instance of config service found, can't load config from nacos");
			return null;
		}
		long timeout = nacosConfigProperties.getTimeout();
		nacosPropertySourceBuilder = new NacosPropertySourceBuilder(configService,
				timeout);
		String name = nacosConfigProperties.getName();

		String dataIdPrefix = nacosConfigProperties.getPrefix();
		if (StringUtils.isEmpty(dataIdPrefix)) {
			dataIdPrefix = name;
		}

		if (StringUtils.isEmpty(dataIdPrefix)) {
			dataIdPrefix = env.getProperty("spring.application.name");
		}

		CompositePropertySource composite = new CompositePropertySource(
				NACOS_PROPERTY_SOURCE_NAME);
		//加载共享配置
		loadSharedConfiguration(composite);
		//加载扩展配置
		loadExtConfiguration(composite);
		//加载自身配置
		loadApplicationConfiguration(composite, dataIdPrefix, nacosConfigProperties, env);
		return composite;
	}

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loadApplicationConfiguration()
我们可以先不管加载共享配置、扩展配置的方法，最终本质上都是去远程服务上读取配置，只是传入的
参数不一样。

  • fileExtension，表示配置文件的扩展名
  • nacosGroup表示分组
  • 加载 dataid=项目名称 的配置
  • 加载 dataid=项目名称+扩展名 的配置
  • 遍历当前配置的激活点（profile），分别循环加载带有profile的dataid配置
private void loadApplicationConfiguration(
			CompositePropertySource compositePropertySource, String dataIdPrefix,
			NacosConfigProperties properties, Environment environment) {
		String fileExtension = properties.getFileExtension();
		String nacosGroup = properties.getGroup();
		// load directly once by default
		loadNacosDataIfPresent(compositePropertySource, dataIdPrefix, nacosGroup,
				fileExtension, true);
		// load with suffix, which have a higher priority than the default
		loadNacosDataIfPresent(compositePropertySource,
				dataIdPrefix + DOT + fileExtension, nacosGroup, fileExtension, true);
		// Loaded with profile, which have a higher priority than the suffix
		for (String profile : environment.getActiveProfiles()) {
			String dataId = dataIdPrefix + SEP1 + profile + DOT + fileExtension;
			loadNacosDataIfPresent(compositePropertySource, dataId, nacosGroup,
					fileExtension, true);
		}

	}

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loadNacosDataIfPresent()
调用 loadNacosPropertySource 加载存在的配置信息。
把加载之后的配置属性保存到CompositePropertySource中。

	private void loadNacosDataIfPresent(final CompositePropertySource composite,
			final String dataId, final String group, String fileExtension,
			boolean isRefreshable) {
		if (null == dataId || dataId.trim().length() < 1) {
			return;
		}
		if (null == group || group.trim().length() < 1) {
			return;
		}
		NacosPropertySource propertySource = this.loadNacosPropertySource(dataId, group,
				fileExtension, isRefreshable);
		this.addFirstPropertySource(composite, propertySource, false);
	}

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loadNacosPropertySource()

	private NacosPropertySource loadNacosPropertySource(final String dataId,
			final String group, String fileExtension, boolean isRefreshable) {
		if (NacosContextRefresher.getRefreshCount() != 0) {
		//是否支持自动刷新，// 如果不支持自动刷新配置则自动从缓存获
取返回			if (!isRefreshable) {
				return NacosPropertySourceRepository.getNacosPropertySource(dataId,
						group);
			}
		}
		//构造器从配置中心获取数据
		return nacosPropertySourceBuilder.build(dataId, group, fileExtension,
				isRefreshable);
	}

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nacosPropertySourceBuilder.build()

	NacosPropertySource build(String dataId, String group, String fileExtension,
			boolean isRefreshable) {
		//调用loadNacosData加载远程数据
		Map<String, Object> p = loadNacosData(dataId, group, fileExtension);
		NacosPropertySource nacosPropertySource = new NacosPropertySource(group, dataId,
				p, new Date(), isRefreshable);
//返回Nacos属性源				
	NacosPropertySourceRepository.collectNacosPropertySource(nacosPropertySource);
		return nacosPropertySource;
	}

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loadNacosData()
加载Nacos的数据。

private Map<String, Object> loadNacosData(String dataId, String group,
			String fileExtension) {
		String data = null;
		try {
			// http远程访问配置中心，获取配置数据
			data = configService.getConfig(dataId, group, timeout);
			 //如果为空，则提示日志
			if (StringUtils.isEmpty(data)) {
				log.warn(
						"Ignore the empty nacos configuration and get it based on dataId[{}] & group[{}]",
						dataId, group);
				return EMPTY_MAP;
			}
			if (log.isDebugEnabled()) {
				log.debug(String.format(
						"Loading nacos data, dataId: '%s', group: '%s', data: %s", dataId,
						group, data));
			}
			//根据扩展名进行数据的解析
			Map<String, Object> dataMap = NacosDataParserHandler.getInstance()
					.parseNacosData(data, fileExtension);
			return dataMap == null ? EMPTY_MAP : dataMap;
		}
		catch (NacosException e) {
			log.error("get data from Nacos error,dataId:{}, ", dataId, e);
		}
		catch (Exception e) {
			log.error("parse data from Nacos error,dataId:{},data:{},", dataId, data, e);
		}
		return EMPTY_MAP;
	}

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getConfigInner()


    private String getConfigInner(String tenant, String dataId, String group, long timeoutMs) throws NacosException {
        group = this.null2defaultGroup(group);
        ParamUtils.checkKeyParam(dataId, group);
        ConfigResponse cr = new ConfigResponse();
        cr.setDataId(dataId);
        cr.setTenant(tenant);
        cr.setGroup(group);
        // 优先使用本地配置
        String content = LocalConfigInfoProcessor.getFailover(this.agent.getName(), dataId, group, tenant);
        if (content != null) {
            LOGGER.warn("[{}] [get-config] get failover ok, dataId={}, group={}, tenant={}, config={}", new Object[]{this.agent.getName(), dataId, group, tenant, ContentUtils.truncateContent(content)});
            cr.setContent(content);
            this.configFilterChainManager.doFilter((IConfigRequest)null, cr);
            content = cr.getContent();
            return content;
        } else {
            try {
                String[] ct = this.worker.getServerConfig(dataId, group, tenant, timeoutMs);
                cr.setContent(ct[0]);
                this.configFilterChainManager.doFilter((IConfigRequest)null, cr);
                content = cr.getContent();
                return content;
            } catch (NacosException var9) {
                if (403 == var9.getErrCode()) {
                    throw var9;
                } else {
                    LOGGER.warn("[{}] [get-config] get from server error, dataId={}, group={}, tenant={}, msg={}", new Object[]{this.agent.getName(), dataId, group, tenant, var9.toString()});
                    LOGGER.warn("[{}] [get-config] get snapshot ok, dataId={}, group={}, tenant={}, config={}", new Object[]{this.agent.getName(), dataId, group, tenant, ContentUtils.truncateContent(content)});
                    content = LocalConfigInfoProcessor.getSnapshot(this.agent.getName(), dataId, group, tenant);
                    cr.setContent(content);
                    this.configFilterChainManager.doFilter((IConfigRequest)null, cr);
                    content = cr.getContent();
                    return content;
                }
            }
        }
    }


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clientWorker.getServerConfig()
通过agent.httpGet发起http请求，获取远程服务的配置。


    public String[] getServerConfig(String dataId, String group, String tenant, long readTimeout) throws NacosException {
        String[] ct = new String[2];
        if (StringUtils.isBlank(group)) {
            group = "DEFAULT_GROUP";
        }

        HttpSimpleClient.HttpResult result = null;

        try {
            List<String> params = null;
            if (StringUtils.isBlank(tenant)) {
                params = new ArrayList(Arrays.asList("dataId", dataId, "group", group));
            } else {
                params = new ArrayList(Arrays.asList("dataId", dataId, "group", group, "tenant", tenant));
            }

            result = this.agent.httpGet("/v1/cs/configs", (List)null, params, this.agent.getEncode(), readTimeout);
        } catch (IOException var10) {
            String message = String.format("[%s] [sub-server] get server config exception, dataId=%s, group=%s, tenant=%s", this.agent.getName(), dataId, group, tenant);
            LOGGER.error(message, var10);
            throw new NacosException(500, var10);
        }

        switch (result.code) {
            case 200:
                LocalConfigInfoProcessor.saveSnapshot(this.agent.getName(), dataId, group, tenant, result.content);
                ct[0] = result.content;
                if (result.headers.containsKey("Config-Type")) {
                    ct[1] = (String)((List)result.headers.get("Config-Type")).get(0);
                } else {
                    ct[1] = ConfigType.TEXT.getType();
                }

                return ct;
            case 403:
                LOGGER.error("[{}] [sub-server-error] no right, dataId={}, group={}, tenant={}", new Object[]{this.agent.getName(), dataId, group, tenant});
                throw new NacosException(result.code, result.content);
            case 404:
                LocalConfigInfoProcessor.saveSnapshot(this.agent.getName(), dataId, group, tenant, (String)null);
                return ct;
            case 409:
                LOGGER.error("[{}] [sub-server-error] get server config being modified concurrently, dataId={}, group={}, tenant={}", new Object[]{this.agent.getName(), dataId, group, tenant});
                throw new NacosException(409, "data being modified, dataId=" + dataId + ",group=" + group + ",tenant=" + tenant);
            default:
                LOGGER.error("[{}] [sub-server-error]  dataId={}, group={}, tenant={}, code={}", new Object[]{this.agent.getName(), dataId, group, tenant, result.code});
                throw new NacosException(result.code, "http error, code=" + result.code + ",dataId=" + dataId + ",group=" + group + ",tenant=" + tenant);
        }
    }

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