环境介绍和使用
环境介绍：
Jdk 1.8nacos-server-1.4.2spring-boot-2.3.5.RELEASEspring-cloud-Hoxton.SR8spring-cloiud-alibab-2.2.5.RELEASE
如果我们需要使用 Nacos 作为配置中心，我们首先需要导入 Nacos Config 的依赖信息，如下所示：
<dependency> <groupId>com.alibaba.cloud</groupId> <artifactId>spring-cloud-starter-alibaba-nacos-config</artifactId> </dependency>
然后再 bootstartp.yml 文件中配置 Nacos 服务信息。
spring: cloud: nacos: config: server-addr: 127.0.0.1:8848
客户端初始化
主要是通过 NacosConfigBootstrapConfiguration 类来进行初始化 NacosConfigManager 、NacosPropertySourceLocator
@Configuration(proxyBeanMethods = false) @ConditionalOnProperty(name = "spring.cloud.nacos.config.enabled", matchIfMissing = true) public class NacosConfigBootstrapConfiguration { @Bean @ConditionalOnMissingBean public NacosConfigManager nacosConfigManager( NacosConfigProperties nacosConfigProperties) { return new NacosConfigManager(nacosConfigProperties); } @Bean public NacosPropertySourceLocator nacosPropertySourceLocator( NacosConfigManager nacosConfigManager) { return new NacosPropertySourceLocator(nacosConfigManager); } // ... }
在 NacosConfigManager 的构造方法中会调用 createConfigService 方法来创建 ConfigService 实例，内部调用工厂方法 ConfigFactory#createConfigService 通过反射实例化一个com.alibaba.nacos.client.config.NacosConfigService 的实例对象。
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); return vendorImpl; } catch (Throwable e) { throw new NacosException(NacosException.CLIENT_INVALID_PARAM, e); } }
NacosPropertySourceLocator 继承 PropertySourceLocator（PropertySourceLocator接口支持扩展自定义配置加载到 Spring Environment中）通过 locate 加载配置信息。
@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); // 共享配置 loadSharedConfiguration(composite); // 拓展配置 loadExtConfiguration(composite); // 应用配置 loadApplicationConfiguration(composite, dataIdPrefix, nacosConfigProperties, env); return composite; }
配置读取过程
配置加载有三个方法 loadSharedConfiguration、loadSharedConfiguration、 loadApplicationConfiguration 以 loadApplicationConfiguration 继续跟进。
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); } }
主要通过 loadNacosDataIfPresent 读取配置信息, 其实我们可以通过参数看出，主要配置文件包含一下及部分： dataId, group, fileExtension
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); }
然后调用 loadNacosPropertySource 最后一步步的会调用到 NacosConfigService#getConfigInner
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); // 优先使用本地配置 String content = LocalConfigInfoProcessor.getFailover(agent.getName(), dataId, group, tenant); if (content != null) { LOGGER.warn("[{}] [get-config] get failover ok, dataId={}, group={}, tenant={}, config={}", agent.getName(), dataId, group, tenant, ContentUtils.truncateContent(content)); cr.setContent(content); configFilterChainManager.doFilter(null, cr); content = cr.getContent(); return content; } try { // 获取远程配置 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; } LOGGER.warn("[{}] [get-config] get from server error, dataId={}, group={}, tenant={}, msg={}", agent.getName(), dataId, group, tenant, ioe.toString()); } LOGGER.warn("[{}] [get-config] get snapshot ok, dataId={}, group={}, tenant={}, config={}", agent.getName(), dataId, group, tenant, ContentUtils.truncateContent(content)); content = LocalConfigInfoProcessor.getSnapshot(agent.getName(), dataId, group, tenant); cr.setContent(content); configFilterChainManager.doFilter(null, cr); content = cr.getContent(); return content; }
