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Spring Cloud Alibaba Nacos Config加载配置详解流程

作者：喜欢小苹果的码农

这篇文章主要介绍了Spring Cloud Alibaba Nacos Config配置中心实现,文中通过示例代码介绍的非常详细，对大家的学习或者工作具有一定的参考学习价值,需要的朋友可以参考下

1、加载节点

SpringBoot启动时，会执行这个方法：SpringApplication#run，这个方法中会调prepareContext来准备上下文，这个方法中调用了applyInitializers方法来执行实现了ApplicationContextInitializer接口的类的initialize方法。其中包括PropertySourceBootstrapConfiguration#initialize 来加载外部的配置。

@Autowired(required = false)
private List<PropertySourceLocator> propertySourceLocators = new ArrayList<>();
public void initialize(ConfigurableApplicationContext applicationContext) {
	...
   for (PropertySourceLocator locator : this.propertySourceLocators) {
       //载入PropertySource
      Collection<PropertySource<?>> source = locator.locateCollection(environment);
      ...
   }
   ...
}
//org.springframework.cloud.bootstrap.config.PropertySourceLocator#locateCollection
default Collection<PropertySource<?>> locateCollection(Environment environment) {
    return locateCollection(this, environment);
}
//org.springframework.cloud.bootstrap.config.PropertySourceLocator#locateCollection
static Collection<PropertySource<?>> locateCollection(PropertySourceLocator locator, Environment environment) {
    //执行locate方法，将PropertySource加载进来
    PropertySource<?> propertySource = locator.locate(environment);
    ...
}

这个类中会注入实现了PropertySourceLocator接口的类，在nacos中是NacosPropertySourceLocator。

在initialize方法中会执行NacosPropertySourceLocator的locate方法，将NacosPropertySource加载进来。

2、NacosPropertySourceLocator的注册

NacosPropertySourceLocator在配置类NacosConfigBootstrapConfiguration中注册。

@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);
   }
   @Bean
   public NacosPropertySourceLocator nacosPropertySourceLocator(
         NacosConfigManager nacosConfigManager) {
      return new NacosPropertySourceLocator(nacosConfigManager);
   }
}

在这里会依次注册NacosConfigProperties，NacosConfigManager，NacosPropertySourceLocator。

3、加载

//com.alibaba.cloud.nacos.client.NacosPropertySourceLocator#locate
public PropertySource<?> locate(Environment env) {
   nacosConfigProperties.setEnvironment(env);
    //获取ConfigService
   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();
    //构建nacosPropertySourceBuilder
   nacosPropertySourceBuilder = new NacosPropertySourceBuilder(configService,
         timeout);
   String name = nacosConfigProperties.getName();
	//获取dataIdPrefix，一次从prefix,name,spring.application.name中获取
   String dataIdPrefix = nacosConfigProperties.getPrefix();
   if (StringUtils.isEmpty(dataIdPrefix)) {
      dataIdPrefix = name;
   }
   if (StringUtils.isEmpty(dataIdPrefix)) {
      dataIdPrefix = env.getProperty("spring.application.name");
   }
	//构建CompositePropertySource：NACOS
   CompositePropertySource composite = new CompositePropertySource(
         NACOS_PROPERTY_SOURCE_NAME);
	//加载share 配置
   loadSharedConfiguration(composite);
   //加载extention 配置
   loadExtConfiguration(composite);
    //加载application配置
   loadApplicationConfiguration(composite, dataIdPrefix, nacosConfigProperties, env);
   return composite;
}

3.1、加载share

private void loadSharedConfiguration(
      CompositePropertySource compositePropertySource) {
   //获取share节点的配置信息
   List<NacosConfigProperties.Config> sharedConfigs = nacosConfigProperties
         .getSharedConfigs();
    //如果不为空，加载
   if (!CollectionUtils.isEmpty(sharedConfigs)) {
      checkConfiguration(sharedConfigs, "shared-configs");
      loadNacosConfiguration(compositePropertySource, sharedConfigs);
   }
}

加载配置，公用方法

//com.alibaba.cloud.nacos.client.NacosPropertySourceLocator#loadNacosConfiguration
private void loadNacosConfiguration(final CompositePropertySource composite,
                                    List<NacosConfigProperties.Config> configs) {
    for (NacosConfigProperties.Config config : configs) {
        loadNacosDataIfPresent(composite, config.getDataId(), config.getGroup(),
                               NacosDataParserHandler.getInstance()
                               .getFileExtension(config.getDataId()),
                               config.isRefresh());
    }
}

//com.alibaba.cloud.nacos.client.NacosPropertySourceLocator#loadNacosDataIfPresent
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;
   }
    //加载NacosPropertySource，后面也会用这个方法
   NacosPropertySource propertySource = this.loadNacosPropertySource(dataId, group,
         fileExtension, isRefreshable);
    //将NacosPropertySource放入第一个
   this.addFirstPropertySource(composite, propertySource, false);
}

加载NacosPropertySource

//com.alibaba.cloud.nacos.client.NacosPropertySourceLocator#loadNacosPropertySource
private NacosPropertySource loadNacosPropertySource(final String dataId,
      final String group, String fileExtension, boolean isRefreshable) {
   //标注@RefreshScope的类的数量不为0，且不允许自动刷新，从缓存加载nacos的配置
    if (NacosContextRefresher.getRefreshCount() != 0) {
      if (!isRefreshable) {
         return NacosPropertySourceRepository.getNacosPropertySource(dataId,
               group);
      }
   }
   return nacosPropertySourceBuilder.build(dataId, group, fileExtension,
         isRefreshable);
}

从缓存中加载

//NacosPropertySourceRepository
private final static ConcurrentHashMap<String, NacosPropertySource> NACOS_PROPERTY_SOURCE_REPOSITORY = new ConcurrentHashMap<>();
public static NacosPropertySource getNacosPropertySource(String dataId,
      String group) {
   return NACOS_PROPERTY_SOURCE_REPOSITORY.get(getMapKey(dataId, group));
}
public static String getMapKey(String dataId, String group) {
   return String.join(NacosConfigProperties.COMMAS, String.valueOf(dataId),
         String.valueOf(group));
}

NacosPropertySourceRepository中缓存了NacosPropertySource

获取配置并加入缓存

//com.alibaba.cloud.nacos.client.NacosPropertySourceBuilder#build
NacosPropertySource build(String dataId, String group, String fileExtension,
      boolean isRefreshable) {
    //获取配置
   List<PropertySource<?>> propertySources = loadNacosData(dataId, group,
         fileExtension);
    //包装成NacosPropertySource
   NacosPropertySource nacosPropertySource = new NacosPropertySource(propertySources,
         group, dataId, new Date(), isRefreshable);
    //加入缓存
   NacosPropertySourceRepository.collectNacosPropertySource(nacosPropertySource);
   return nacosPropertySource;
}
//com.alibaba.cloud.nacos.client.NacosPropertySourceBuilder#loadNacosData
private List<PropertySource<?>> loadNacosData(String dataId, String group,
      String fileExtension) {
   String data = null;
   try {
       //获取配置
      data = configService.getConfig(dataId, group, timeout);
      if (StringUtils.isEmpty(data)) {
         log.warn(
               "Ignore the empty nacos configuration and get it based on dataId[{}] & group[{}]",
               dataId, group);
         return Collections.emptyList();
      }
      if (log.isDebugEnabled()) {
         log.debug(String.format(
               "Loading nacos data, dataId: '%s', group: '%s', data: %s", dataId,
               group, data));
      }
      return NacosDataParserHandler.getInstance().parseNacosData(dataId, data,
            fileExtension);
   }
   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 Collections.emptyList();
}
//com.alibaba.nacos.client.config.NacosConfigService#getConfig
public String getConfig(String dataId, String group, long timeoutMs) throws NacosException {
    return getConfigInner(namespace, dataId, group, timeoutMs);
}

//com.alibaba.nacos.client.config.NacosConfigService#getConfigInner
private String getConfigInner(String tenant, String dataId, String group, long timeoutMs) throws NacosException {
    group = blank2defaultGroup(group);
    ParamUtils.checkKeyParam(dataId, group);
    //声明响应
    ConfigResponse cr = new ConfigResponse();
    //设置dataId，tenant，group
    cr.setDataId(dataId);
    cr.setTenant(tenant);
    cr.setGroup(group);
    // use local config first
    //先从本地缓存中加载
    String content = LocalConfigInfoProcessor.getFailover(worker.getAgentName(), dataId, group, tenant);
    if (content != null) {
        LOGGER.warn("[{}] [get-config] get failover ok, dataId={}, group={}, tenant={}, config={}",
                worker.getAgentName(), dataId, group, tenant, ContentUtils.truncateContent(content));
        cr.setContent(content);
        String encryptedDataKey = LocalEncryptedDataKeyProcessor
                .getEncryptDataKeyFailover(agent.getName(), dataId, group, tenant);
        cr.setEncryptedDataKey(encryptedDataKey);
        configFilterChainManager.doFilter(null, cr);
        content = cr.getContent();
        return content;
    }
    try {
        //从服务器获取配置
        ConfigResponse response = worker.getServerConfig(dataId, group, tenant, timeoutMs, false);
        cr.setContent(response.getContent());
        cr.setEncryptedDataKey(response.getEncryptedDataKey());
        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={}",
                worker.getAgentName(), dataId, group, tenant, ioe.toString());
    }
    LOGGER.warn("[{}] [get-config] get snapshot ok, dataId={}, group={}, tenant={}, config={}",
            worker.getAgentName(), dataId, group, tenant, ContentUtils.truncateContent(content));
    content = LocalConfigInfoProcessor.getSnapshot(worker.getAgentName(), dataId, group, tenant);
    cr.setContent(content);
    String encryptedDataKey = LocalEncryptedDataKeyProcessor
            .getEncryptDataKeyFailover(agent.getName(), dataId, group, tenant);
    cr.setEncryptedDataKey(encryptedDataKey);
    configFilterChainManager.doFilter(null, cr);
    content = cr.getContent();
    return content;
}

将NacosPropertySource加入composite的第一个

//com.alibaba.cloud.nacos.client.NacosPropertySourceLocator#addFirstPropertySource
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);
}

3.2、加载extention

private void loadExtConfiguration(CompositePropertySource compositePropertySource) {
    //获取extention节点的配置信息
   List<NacosConfigProperties.Config> extConfigs = nacosConfigProperties
         .getExtensionConfigs();
    //如果不为空，加载
   if (!CollectionUtils.isEmpty(extConfigs)) {
      checkConfiguration(extConfigs, "extension-configs");
      loadNacosConfiguration(compositePropertySource, extConfigs);
   }
}

3.3、加载主配置文件

private void loadApplicationConfiguration(
      CompositePropertySource compositePropertySource, String dataIdPrefix,
      NacosConfigProperties properties, Environment environment) {
   //获取文件扩展名
   String fileExtension = properties.getFileExtension();
    //获取group
   String nacosGroup = properties.getGroup();
   // load directly once by default
    //加载nacos的配置
   loadNacosDataIfPresent(compositePropertySource, dataIdPrefix, nacosGroup,
         fileExtension, true);
   // load with suffix, which have a higher priority than the default
    //加载带后缀的配置，优先级高于上一个
   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;
       //加载带profile，文件格式后缀的配置，优先级高于上一个
      loadNacosDataIfPresent(compositePropertySource, dataId, nacosGroup,
            fileExtension, true);
   }
}

这里会加载至少三个nacos上面的配置文件，按优先级依次为application,application.yaml,application-dev.yaml。

到此这篇关于Spring Cloud Alibaba Nacos Config加载配置详解流程的文章就介绍到这了,更多相关Spring Cloud Alibaba Nacos Config 内容请搜索脚本之家以前的文章或继续浏览下面的相关文章希望大家以后多多支持脚本之家！

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