[享学Netflix] 十五、Archaius和Spring Cloud的集成

<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-netflix-archaius</artifactId>
    <version>2.2.1.RELEASE</version>
</dependency>

<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-netflix-archaius</artifactId>
    <version>2.2.1.RELEASE</version>
</dependency>

<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-netflix-archaius</artifactId>
    <version>2.2.1.RELEASE</version>
</dependency>

public class ConfigurableEnvironmentConfiguration extends AbstractConfiguration {

	// 管理着Spring的所有属性们
	private final ConfigurableEnvironment environment;
	public ConfigurableEnvironmentConfiguration(ConfigurableEnvironment environment) {
		this.environment = environment;
	}
	...
	@Override
	public boolean isEmpty() {
		return !getKeys().hasNext();
	}
	@Override
	public boolean containsKey(String key) {
		return this.environment.containsProperty(key);
	}
	@Override
	public Object getProperty(String key) {
		return this.environment.getProperty(key);
	}

	// 拿到所有的属性源PropertySource出来，注意这里需要处理CompositePropertySource这种哟
	@Override
	public Iterator<String> getKeys() {
		List<String> result = new ArrayList<>();
		for (Map.Entry<String, PropertySource<?>> entry : getPropertySources().entrySet()) {
			PropertySource<?> source = entry.getValue();
			if (source instanceof EnumerablePropertySource) {
				EnumerablePropertySource<?> enumerable = (EnumerablePropertySource<?>) source;
				for (String name : enumerable.getPropertyNames()) {
					result.add(name);
				}
			}
		}
		return result.iterator();
	}

	...
}

public final class ArchaiusDelegatingProxyUtils {

	// Application作为属性的key名称
	public static String APPLICATION_CONTEXT = ApplicationContext.class.getName();

	// 简单的说：就是去ApplicationContext里面去getBean
	// 前提是：ApplicationContext实例必须在全局的Configuration里面了~
	public static <T> T getNamedInstance(Class<T> type, String name) {
		ApplicationContext context = (ApplicationContext) ConfigurationManager.getConfigInstance().getProperty(APPLICATION_CONTEXT);
		return context != null && context.containsBean(name) ? context.getBean(name, type) : null;
	}
	// name = prefix + type.getSimpleName();
	public static <T> T getInstanceWithPrefix(Class<T> type, String prefix) {
		String name = prefix + type.getSimpleName();
		return getNamedInstance(type, name);
	}

	// 调用此方法：可以把ApplicationContext实例，放进Configuration里面
	public static void addApplicationContext(ConfigurableApplicationContext context) {
		AbstractConfiguration config = ConfigurationManager.getConfigInstance();
		config.clearProperty(APPLICATION_CONTEXT);
		config.setProperty(APPLICATION_CONTEXT, context);
	}
}

@Endpoint(id = "archaius")
public class ArchaiusEndpoint {

	// 只有一个读方法而已
	@ReadOperation
	public Map<String, Object> invoke() {
		Map<String, Object> map = new LinkedHashMap<>();
		AbstractConfiguration config = ConfigurationManager.getConfigInstance();
		if (config instanceof ConcurrentCompositeConfiguration) {
			ConcurrentCompositeConfiguration composite = (ConcurrentCompositeConfiguration) config;
			for (Configuration item : composite.getConfigurations()) {
				append(map, item);
			}
		} else {
			append(map, config);
		}
		return map;
	}

	// 核心在append方法，往Map里放值
	// 需要注意的是：前面三种属性源都是不会添加进去的哦，就连ConfigurableEnvironmentConfiguration都不给你访问
	private void append(Map<String, Object> map, Configuration config) {
		if (config instanceof ConfigurableEnvironmentConfiguration)
			return;
		if (config instanceof SystemConfiguration)
			return;
		if (config instanceof EnvironmentConfiguration)
			return;
		for (Iterator<String> iter = config.getKeys(); iter.hasNext();) {
			String key = iter.next();
			map.put(key, config.getProperty(key));
		}
	}

}

public static void main(String[] args) {
    AbstractConfiguration config = ConfigurationManager.getConfigInstance();
    config.addProperty("name", "YourBatman");
    config.addProperty("age", 18);

    ConfigurableApplicationContext context = SpringApplication.run(CloudFeignApplication.class, args);
    // 这算是一个Bug，当把Context放进去后，如果访问`archaius`端点，会报错：序列化异常，所以此处展示注释掉喽
    // ArchaiusDelegatingProxyUtils.addApplicationContext(context);
}

{"name":"YourBatman","age":18}

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 })
@AutoConfigureOrder(Ordered.HIGHEST_PRECEDENCE) //配置的自动配置，优先级最高
public class ArchaiusAutoConfiguration {

	// 避免多次初始化的开关
	private static final AtomicBoolean initialized = new AtomicBoolean(false);
	// Spring容器的环境
	@Autowired
	private ConfigurableEnvironment env;
	// 由此可知：你若要扩展属性Configuration，直接往容器里扔一个Bean即可~~~非常方便
	@Autowired(required = false)
	private List<AbstractConfiguration> externalConfigurations = new ArrayList<>();

	// 用于加载Archaius的那些默认行为，比如类路径下的config.properties
	private static DynamicURLConfiguration defaultURLConfig;


	// 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
	@Bean
	public static ConfigurableEnvironmentConfiguration configurableEnvironmentConfiguration(ConfigurableEnvironment env, ApplicationContext context) {
		ConfigurableEnvironmentConfiguration envConfig = new ConfigurableEnvironmentConfiguration(env);
		configureArchaius(envConfig, env, externalConfigurations);
		return envConfig;
	}

	protected static void configureArchaius(...) {
		// 保证只初始化一次
		if (initialized.compareAndSet(false, true)) {
			
			// 把应用名称，appName放进系统属性（全局配置）
			String appName = env.getProperty("spring.application.name");
			if (appName == null) {
				appName = "application";
				log.warn("No spring.application.name found, defaulting to 'application'");
			}
			System.setProperty(DeploymentContext.ContextKey.appId.getKey(), appName);


			// 请注意：它是一个组合属性，将会组合下面的一些配置们
			ConcurrentCompositeConfiguration config = new ConcurrentCompositeConfiguration();
			
			... // 把用户额外配置的属性都放进来
			config.addConfiguration(externalConfig);
			// 把Spring Env属性放进来
			config.addConfiguration(envConfig, ConfigurableEnvironmentConfiguration.class.getSimpleName());
			
			// 把形如config.properties这种配置加进来（默认是empty哦）
			defaultURLConfig = new DynamicURLConfiguration();
			config.addConfiguration(defaultURLConfig, URL_CONFIG_NAME);

			// 如果系统属性、系统环境没有被禁止
			// 那就把new SystemConfiguration()、 new EnvironmentConfiguration()加进来
			if (!Boolean.getBoolean(DISABLE_DEFAULT_SYS_CONFIG))
			if (!Boolean.getBoolean(DISABLE_DEFAULT_ENV_CONFIG))
			
			// 把组合好的配置，安装到全局的Configuration里面去
			// 需要注意的是：这里install是指定了外部config的
			// 所以即使你内部`ConfigurationManager#createDefaultConfigInstance`过，最终也会被这个给替换掉
			// 但其里面的内容都会被copy过来，不会丢失哦~~~~
			// 所以这个install是专门用于设置外部config进来的~~~~
			... ConfigurationManager.install(config);
			// addArchaiusConfiguration(config);
		}
	}

	...
		@Bean
		@ConditionalOnEnabledEndpoint
		protected ArchaiusEndpoint archaiusEndpoint() {
			return new ArchaiusEndpoint();
		}
	...
}

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>