[享学Archaius] 十七、Spring的Environment是如何整合进Archaius从而实现全局共享的？

org.springframework.boot.autoconfigure.EnableAutoConfiguration=\
org.springframework.cloud.netflix.archaius.ArchaiusAutoConfiguration

// 说明：ConfigurationBuilder是Apache Commons Configuration1.x的核心API
// ConcurrentCompositeConfiguration是archaius1.x(0.x)的核心API
@Configuration(proxyBeanMethods = false)
@ConditionalOnClass({ ConcurrentCompositeConfiguration.class, ConfigurationBuilder.class })
// 优先级最高。毕竟一切都得配置先行嘛
@AutoConfigureOrder(Ordered.HIGHEST_PRECEDENCE) 
public class ArchaiusAutoConfiguration {

	private static final AtomicBoolean initialized = new AtomicBoolean(false);
	@Autowired
	private ConfigurableEnvironment env;
	@Autowired(required = false)
	private List<AbstractConfiguration> externalConfigurations = new ArrayList<>();

	private static DynamicURLConfiguration defaultURLConfig;
}

ArchaiusAutoConfiguration：

	// 这是核心初始化流程：会把容器内的配置都放在一起，并且做一些初始化的动作
	// 把用户自定义的externalConfigurations都放进来（自己获取）
	@Bean
	public static ConfigurableEnvironmentConfiguration configurableEnvironmentConfiguration(ConfigurableEnvironment env, ApplicationContext context) {
		// externalConfigurations的获取。其实效果同@Autowired，只是这是static方法不能直接使用而已~
		Map<String, AbstractConfiguration> abstractConfigurationMap = context.getBeansOfType(AbstractConfiguration.class);
		List<AbstractConfiguration> externalConfigurations = new ArrayList<>(abstractConfigurationMap.values());

		// 组合配置
		ConfigurableEnvironmentConfiguration envConfig = new ConfigurableEnvironmentConfiguration(env);
		configureArchaius(envConfig, env, externalConfigurations);
		return envConfig;
	}


	protected static void configureArchaius(ConfigurableEnvironmentConfiguration envConfig, ConfigurableEnvironment env, List<AbstractConfiguration> externalConfigurations) {
		// initialized是静态变量：它能保证全局只会初始化一次
		if (initialized.compareAndSet(false, true)) {
			String appName = env.getProperty("spring.application.name");
			if (appName == null) {
				appName = "application";
				log.warn("No spring.application.name found, defaulting to 'application'");
			}
			// 部署上下文使用的APPId为应用名
			System.setProperty(DeploymentContext.ContextKey.appId.getKey(), appName);


			// 组合配置，我们知道`ConfigurationManager`它最终也是生成的一个组合配置
			// 这里因为要加入Spring的Environment 所以重新组装一次
			ConcurrentCompositeConfiguration config = new ConcurrentCompositeConfiguration();

			
			// 1、自定义配置们放进来
			if (externalConfigurations != null) {
				for (AbstractConfiguration externalConfig : externalConfigurations) {
					config.addConfiguration(externalConfig);
				}
			}
			// 2、Spring的Environment环境放进来
			config.addConfiguration(envConfig, ConfigurableEnvironmentConfiguration.class.getSimpleName());

			// 3、加载`Archaius`自己的配置们放进来  所以config.properties等均还是有效的（且天生支持动态修改）
			defaultURLConfig = new DynamicURLConfiguration();
			try {
				config.addConfiguration(defaultURLConfig, URL_CONFIG_NAME);
			} catch (Throwable ex) {
				log.error("Cannot create config from " + defaultURLConfig, ex);
			}

			// 默认均会条件进来
			if (!Boolean.getBoolean(DISABLE_DEFAULT_SYS_CONFIG)) {
				SystemConfiguration sysConfig = new SystemConfiguration();
				config.addConfiguration(sysConfig, SYS_CONFIG_NAME);
			}
			if (!Boolean.getBoolean(DISABLE_DEFAULT_ENV_CONFIG)) {
				EnvironmentConfiguration environmentConfiguration = new EnvironmentConfiguration();
				config.addConfiguration(environmentConfiguration, ENV_CONFIG_NAME);
			}
			ConcurrentCompositeConfiguration appOverrideConfig = new ConcurrentCompositeConfiguration();
			config.addConfiguration(appOverrideConfig, APPLICATION_PROPERTIES);
			config.setContainerConfigurationIndex(config.getIndexOfConfiguration(appOverrideConfig));

			// 简单的说就是调用：ConfigurationManager.install(config);
			// 把该组合配置放进全局配置里
			addArchaiusConfiguration(config);
		} else { // 全局配置已经安装过 无需再安装
			log.warn("Netflix ConfigurationManager has already been installed, unable to re-install");
		}
	}

my.name = YourBatman
my.age = 100

my:
  age: 18

@SpringBootApplication
public class Application {

    public static void main(String[] args) {
        ConfigurableApplicationContext context = SpringApplication.run(Application.class, args);

        // 读取配置
        AbstractConfiguration config = ConfigurationManager.getConfigInstance();
        System.out.println(config.getString("my.name"));
        System.out.println(config.getString("my.age"));

        DynamicStringProperty name = DynamicPropertyFactory.getInstance().getStringProperty("my.name", "defualtName");
        DynamicIntProperty age = DynamicPropertyFactory.getInstance().getIntProperty("my.age", 0);
        System.out.println(name);
        System.out.println(age);

        context.close();
    }

}

YourBatman
18
DynamicProperty: {name=my.name, current value=YourBatman}
DynamicProperty: {name=my.age, current value=18}

ArchaiusAutoConfiguration：

	// 它是个ApplicationListener，监听EnvironmentChangeEvent事件
	@Configuration(proxyBeanMethods = false)
	@ConditionalOnProperty(value = "archaius.propagate.environmentChangedEvent", matchIfMissing = true)
	@ConditionalOnClass(EnvironmentChangeEvent.class)
	protected static class PropagateEventsConfiguration implements ApplicationListener<EnvironmentChangeEvent> {

		@Autowired
		private Environment env;

		@Override
		public void onApplicationEvent(EnvironmentChangeEvent event) {
			// 拿到全局配置
			AbstractConfiguration manager = ConfigurationManager.getConfigInstance();

			// 从事件里拿到所有改变了的Key们，一个一个的处理
			for (String key : event.getKeys()) {
				// 拿到注册在Configuration上的所有事件门，一个一个的触发他们的configurationChanged方法
				// 事件类型是：AbstractConfiguration.EVENT_SET_PROPERTY;
				for (ConfigurationListener listener : manager.getConfigurationListeners()) {
					Object source = event.getSource();
					// TODO: Handle add vs set vs delete?
					int type = AbstractConfiguration.EVENT_SET_PROPERTY;
					// 改变后的value从env里获取（可能为null哦~）
					// 当然一般建议动态修改，而非删除，请务必注意喽
					String value = this.env.getProperty(key);
					boolean beforeUpdate = false;
					listener.configurationChanged(new ConfigurationEvent(source, type, key, value, beforeUpdate));
				}
			}
		}
	}

<dependency>
    <groupId>com.netflix.archaius</groupId>
    <artifactId>archaius2-core</artifactId>
    <version>2.3.16</version>
</dependency>