環(huán)境：Springboot2.3.12.RELEASE + Spring Cloud Alibaba2.2.5.RELEASE + Spring Cloud Hoxton.SR12

應(yīng)用的核心技術(shù)是：自定義PropertySourceLocator，然后配置spring.factories

在如下包中配置：

spring-cloud-context-xxx.jar中

org.springframework.cloud.bootstrap.BootstrapConfiguration=org.springframework.cloud.bootstrap.config.PropertySourceBootstrapConfiguration

Nacos加載配置的時候默認(rèn)會通過一下三個DataId加載數(shù)據(jù)：

核心類：NacosPropertySourceLocator

自動配置核心

@Configuration(proxyBeanMethods = false)@ConditionalOnProperty(name = “spring.cloud.nacos.config.enabled”, matchIfMissing = true)public class NacosConfigBootstrapConfiguration { // Nacos Config相關(guān)的配置屬性 @Bean @ConditionalOnMissingBean public NacosConfigProperties nacosConfigProperties() { return new NacosConfigProperties(); } // 管理Nacos Config相關(guān)的服務(wù) @Bean @ConditionalOnMissingBean public NacosConfigManager nacosConfigManager( NacosConfigProperties nacosConfigProperties) { return new NacosConfigManager(nacosConfigProperties); } // 核心類自定義啟動加載配置文件（Bootstraps） @Bean public NacosPropertySourceLocator nacosPropertySourceLocator( NacosConfigManager nacosConfigManager) { return new NacosPropertySourceLocator(nacosConfigManager); }}org.springframework.cloud.bootstrap.BootstrapConfiguration=com.alibaba.cloud.nacos.NacosConfigBootstrapConfiguration

自定義屬性源

public class NacosPropertySourceLocator implements PropertySourceLocator { private NacosPropertySourceBuilder nacosPropertySourceBuilder; private NacosConfigProperties nacosConfigProperties; private NacosConfigManager nacosConfigManager; public NacosPropertySourceLocator(NacosConfigManager nacosConfigManager) { this.nacosConfigManager = nacosConfigManager; this.nacosConfigProperties = nacosConfigManager.getNacosConfigProperties(); } public PropertySource locate(Environment env) { nacosConfigProperties.setEnvironment(env); // 關(guān)鍵通過NacosConfigManager獲取ConfigService服務(wù) ConfigService configService = nacosConfigManager.getConfigService(); // … long timeout = nacosConfigProperties.getTimeout(); nacosPropertySourceBuilder = new NacosPropertySourceBuilder(configService, timeout); // 下面這些設(shè)置就是對應(yīng)從配置文件中獲取 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);// NACOS_PROPERTY_SOURCE_NAME = NACOS // 加載共享配置 loadSharedConfiguration(composite); // 加載擴(kuò)展配置 loadExtConfiguration(composite); // 加載應(yīng)用程序配置（這里就以應(yīng)用程序配置，深入查看） loadApplicationConfiguration(composite, dataIdPrefix, nacosConfigProperties, env); return composite; }}

獲取配置服務(wù)

ConfigService配置服務(wù)是獲取配置信息的核心方法：

public interface ConfigService { // 獲取配置 String getConfig(String dataId, String group, long timeoutMs) throws NacosException; // 獲取配置并設(shè)置監(jiān)聽 String getConfigAndSignListener(String dataId, String group, long timeoutMs, Listener listener) throws NacosException; // 給配置添加監(jiān)聽 void addListener(String dataId, String group, Listener listener) throws NacosException; // 發(fā)布配置 boolean publishConfig(String dataId, String group, String content) throws NacosException; // 刪除配置 boolean removeConfig(String dataId, String group) throws NacosException; // 刪除監(jiān)聽 void removeListener(String dataId, String group, Listener listener); // 獲取服務(wù)狀態(tài) String getServerStatus(); // 關(guān)閉資源服務(wù) void shutDown() throws NacosException;}

NacosConfigManager

public class NacosConfigManager { private static ConfigService service = null; private NacosConfigProperties nacosConfigProperties; public NacosConfigManager(NacosConfigProperties nacosConfigProperties) { this.nacosConfigProperties = nacosConfigProperties; // 創(chuàng)建配置服務(wù) createConfigService(nacosConfigProperties); } static ConfigService createConfigService( NacosConfigProperties nacosConfigProperties) { if (Objects.isNull(service)) { synchronized (NacosConfigManager.class) { try { if (Objects.isNull(service)) { // 通過工廠創(chuàng)建服務(wù) // assembleConfigServiceProperties方法 // 就是收集關(guān)于Nacos所有配置信息，如：地址，端口，用戶名，密碼等 // 詳細(xì)查看NacosConfigProperties#assembleConfigServiceProperties service = NacosFactory.createConfigService( nacosConfigProperties.assembleConfigServiceProperties()); } } // … } } return service; }}// NacosFactorypublic class NacosFactory { public static ConfigService createConfigService(Properties properties) throws NacosException { return ConfigFactory.createConfigService(properties); }}public class ConfigFactory { public static ConfigService createConfigService(Properties properties) throws NacosException { try { Class driverImplClass = Class.forName(“com.alibaba.nacos.client.config.NacosConfigService”); Constructor constructor = driverImplClass.getConstructor(Properties.class); ConfigService vendorImpl = (ConfigService) constructor.newInstance(properties); // 通過反射構(gòu)造了NacosConfigservice,同時設(shè)置屬性信息 // 這些屬性信息就是一些Naocs服務(wù)的地址，端口，用戶名，密碼等信息 return vendorImpl; } catch (Throwable e) { throw new NacosException(NacosException.CLIENT_INVALID_PARAM, e); } }}

到此就得到了一個ConfigService服務(wù)類NacosConfigService。

獲取應(yīng)用程序配置

接著95.2獲取到了ConfigService以后繼續(xù)執(zhí)行

public class NacosPropertySourceLocator implements PropertySourceLocator { private NacosPropertySourceBuilder nacosPropertySourceBuilder; public PropertySource locate(Environment env) { nacosConfigProperties.setEnvironment(env); // 關(guān)鍵通過NacosConfigManager獲取ConfigService服務(wù) ConfigService configService = nacosConfigManager.getConfigService(); // … nacosPropertySourceBuilder = new NacosPropertySourceBuilder(configService, timeout); CompositePropertySource composite = new CompositePropertySource( NACOS_PROPERTY_SOURCE_NAME); loadApplicationConfiguration(composite, dataIdPrefix, nacosConfigProperties, env); return composite; } private void loadApplicationConfiguration( CompositePropertySource compositePropertySource, String dataIdPrefix, NacosConfigProperties properties, Environment environment) { // 獲取文件擴(kuò)展 String fileExtension = properties.getFileExtension(); // 獲取分組 String nacosGroup = properties.getGroup(); // … // load with suffix, which have a higher priority than the default // 這里就以這里為例 loadNacosDataIfPresent(compositePropertySource, dataIdPrefix + DOT + fileExtension, nacosGroup, fileExtension, true); // Loaded with profile, which have a higher priority than the suffix // 這里會根據(jù)不同配置的profiles再次加載不同環(huán)境的配置 for (String profile : environment.getActiveProfiles()) { String dataId = dataIdPrefix + SEP1 + profile + DOT + fileExtension; loadNacosDataIfPresent(compositePropertySource, dataId, nacosGroup, fileExtension, true); } } 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; } // 加載Nacos屬性源 NacosPropertySource propertySource = this.loadNacosPropertySource(dataId, group, fileExtension, isRefreshable); this.addFirstPropertySource(composite, propertySource, false); } private NacosPropertySource loadNacosPropertySource(final String dataId, final String group, String fileExtension, boolean isRefreshable) { // … return nacosPropertySourceBuilder.build(dataId, group, fileExtension, isRefreshable); } private void addFirstPropertySource(final CompositePropertySource composite, NacosPropertySource nacosPropertySource, boolean ignoreEmpty) { if (null == nacosPropertySource || null == composite) { return; } if (ignoreEmpty && nacosPropertySource.getSource().isEmpty()) { return; } composite.addFirstPropertySource(nacosPropertySource); }}// 這里面開始加載數(shù)據(jù)public class NacosPropertySourceBuilder { NacosPropertySource build(String dataId, String group, String fileExtension, boolean isRefreshable) { Map p = loadNacosData(dataId, group, fileExtension); NacosPropertySource nacosPropertySource = new NacosPropertySource(group, dataId, p, new Date(), isRefreshable); NacosPropertySourceRepository.collectNacosPropertySource(nacosPropertySource); return nacosPropertySource; } // 加載數(shù)據(jù) private Map loadNacosData(String dataId, String group, String fileExtension) { String data = null; try { // 通過ConfigService加載配置內(nèi)容（從遠(yuǎn)程服務(wù)獲?。? data = configService.getConfig(dataId, group, timeout); if (StringUtils.isEmpty(data)) { return EMPTY_MAP; } Map dataMap = NacosDataParserHandler.getInstance() .parseNacosData(data, fileExtension); return dataMap == null ? EMPTY_MAP : dataMap; } // … return EMPTY_MAP; }}public class NacosConfigService implements ConfigService { public String getConfig(String dataId, String group, long timeoutMs) throws NacosException { return getConfigInner(namespace, dataId, group, timeoutMs); } private String getConfigInner(String tenant, String dataId, String group, long timeoutMs) throws NacosException { group = null2defaultGroup(group); ParamUtils.checkKeyParam(dataId, group); ConfigResponse cr = new ConfigResponse(); cr.setDataId(dataId); cr.setTenant(tenant); cr.setGroup(group); // 這里會從緩存文件中獲取，如果能獲取就不會再從遠(yuǎn)程加載了 // 會從如下緩存目錄下加載配置： // System.getProperty("JM.SNAPSHOT.PATH", // System.getProperty("user.home")) + File.separator + "nacos" // + File.separator + "config" String content = LocalConfigInfoProcessor.getFailover(agent.getName(), dataId, group, tenant); if (content != null) { cr.setContent(content); configFilterChainManager.doFilter(null, cr); content = cr.getContent(); return content; } try { // 緩存總無法獲取則從遠(yuǎn)程服務(wù)上拉取數(shù)據(jù) String[] ct = worker.getServerConfig(dataId, group, tenant, timeoutMs); cr.setContent(ct[0]); configFilterChainManager.doFilter(null, cr); content = cr.getContent(); return content; } catch (NacosException ioe) { if (NacosException.NO_RIGHT == ioe.getErrCode()) { throw ioe; } } content = LocalConfigInfoProcessor.getSnapshot(agent.getName(), dataId, group, tenant); cr.setContent(content); configFilterChainManager.doFilter(null, cr); content = cr.getContent(); return content; }}public class ClientWorker implements Closeable { // 這里就是從遠(yuǎn)程服務(wù)拉取配置 public String[] getServerConfig(String dataId, String group, String tenant, long readTimeout) throws NacosException { String[] ct = new String[2]; if (StringUtils.isBlank(group)) { group = Constants.DEFAULT_GROUP; } HttpRestResult result = null; try { Map params = new HashMap(3); if (StringUtils.isBlank(tenant)) { params.put("dataId", dataId); params.put("group", group); } else { params.put("dataId", dataId); params.put("group", group); params.put("tenant", tenant); } result = agent.httpGet(Constants.CONFIG_CONTROLLER_PATH, null, params, agent.getEncode(), readTimeout); } catch (Exception ex) { throw new NacosException(NacosException.SERVER_ERROR, ex); } switch (result.getCode()) { case HttpURLConnection.HTTP_OK: // 獲取成功后會將數(shù)據(jù)保存到緩存目錄下 LocalConfigInfoProcessor.saveSnapshot(agent.getName(), dataId, group, tenant, result.getData()); ct[0] = result.getData(); if (result.getHeader().getValue(CONFIG_TYPE) != null) { ct[1] = result.getHeader().getValue(CONFIG_TYPE); } else { ct[1] = ConfigType.TEXT.getType(); } return ct; case HttpURLConnection.HTTP_NOT_FOUND: LocalConfigInfoProcessor.saveSnapshot(agent.getName(), dataId, group, tenant, null); return ct; case HttpURLConnection.HTTP_CONFLICT: { throw new NacosException(NacosException.CONFLICT, "data being modified, dataId=" + dataId + ",group=" + group + ",tenant=" + tenant); } throw new NacosException(result.getCode(), result.getMessage()); } default: { throw new NacosException(result.getCode(), "http error, code=" + result.getCode() + ",dataId=" + dataId + ",group=" + group + ",tenant=" + tenant); } } }}

到此就完成了遠(yuǎn)程配置數(shù)據(jù)的加載

總結(jié)：Nacos Config先從本地緩存中獲取數(shù)據(jù)，如果不能獲取才從遠(yuǎn)程拉?。ㄈ绻h(yuǎn)程服務(wù)無法連接，那么會不斷重試，前提是本地能夠加載到數(shù)據(jù)，否則服務(wù)將無法正常啟動）。

完畢?。。?/p>

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