contextInitialized

EurekaBootStrap#contextInitialized

    @Override
    public void contextInitialized(ServletContextEvent event) {
        try {
             //初始化eureka的环境 
            initEurekaEnvironment();
            initEurekaServerContext();

            ServletContext sc = event.getServletContext();
            sc.setAttribute(EurekaServerContext.class.getName(), serverContext);
        } catch (Throwable e) {
            logger.error("Cannot bootstrap eureka server :", e);
            throw new RuntimeException("Cannot bootstrap eureka server :", e);
        }
    }

initEurekaEnvironment

    protected void initEurekaEnvironment() throws Exception {
        logger.info("Setting the eureka configuration..");
//获取数据中心
        String dataCenter = ConfigurationManager.getConfigInstance().getString(EUREKA_DATACENTER);
        if (dataCenter == null) {
            logger.info("Eureka data center value eureka.datacenter is not set, defaulting to default");
            ConfigurationManager.getConfigInstance().setProperty(ARCHAIUS_DEPLOYMENT_DATACENTER, DEFAULT);
        } else {
            ConfigurationManager.getConfigInstance().setProperty(ARCHAIUS_DEPLOYMENT_DATACENTER, dataCenter);
        }
        String environment = ConfigurationManager.getConfigInstance().getString(EUREKA_ENVIRONMENT);
//如果没有设置环境的话，默认设置为测试环境
        if (environment == null) {
            ConfigurationManager.getConfigInstance().setProperty(ARCHAIUS_DEPLOYMENT_ENVIRONMENT, TEST);
            logger.info("Eureka environment value eureka.environment is not set, defaulting to test");
        }
    }

getConfigInstance

是在netflix.config的这个包下面的，也就是说他是eureka引用的一个jar包
ConfigurationManager#getConfigInstance

    public static AbstractConfiguration getConfigInstance() {
        if (instance == null) {
            synchronized (ConfigurationManager.class) {
                if (instance == null) {
                    instance = getConfigInstance(Boolean.getBoolean(DynamicPropertyFactory.DISABLE_DEFAULT_CONFIG));
                }
            }
        }
        return instance;
    }

getConfigInstance 重载

ConfigurationManager#getConfigInstance

//注意的是 这里用到了 单例模式，就是所谓的 double check，但是依旧会出现多线程的问题
//所以，还是推荐使用volatile+double check
    private static AbstractConfiguration getConfigInstance(boolean defaultConfigDisabled) {
        if (instance == null && !defaultConfigDisabled) {
            instance = createDefaultConfigInstance();
            registerConfigBean();
        }
        return instance;        
    }

//defaultConfigDisabled默认是false，它的意思是 是不是要延迟加载动态属性工厂DynamicPropertyFactory
    private static AbstractConfiguration getConfigInstance(boolean defaultConfigDisabled) {
        if (instance == null && !defaultConfigDisabled) {
//很明显，创建一个默认的配置
            instance = createDefaultConfigInstance();
//将这个配置注册到bean中
            registerConfigBean();
        }
        return instance;        
    }

createDefaultConfigInstance

    private static AbstractConfiguration createDefaultConfigInstance() {
//创建一个空的 CompositeConfiguration 对象，然后可以添加一些其他配置文件
        ConcurrentCompositeConfiguration config = new ConcurrentCompositeConfiguration();  
        try {
            DynamicURLConfiguration defaultURLConfig = new DynamicURLConfiguration();
            config.addConfiguration(defaultURLConfig, URL_CONFIG_NAME);
        } catch (Throwable e) {
            logger.warn("Failed to create default dynamic configuration", e);
        }
        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 envConfig = new EnvironmentConfiguration();
            config.addConfiguration(envConfig, ENV_CONFIG_NAME);
        }
        ConcurrentCompositeConfiguration appOverrideConfig = new ConcurrentCompositeConfiguration();
        config.addConfiguration(appOverrideConfig, APPLICATION_PROPERTIES);
        config.setContainerConfigurationIndex(config.getIndexOfConfiguration(appOverrideConfig));
        return config;
    }
    

initEurekaServerContext

    protected void initEurekaServerContext() throws Exception {
//new config 会调用他的构造方法，构造方法中直接调用了init方法
        EurekaServerConfig eurekaServerConfig = new DefaultEurekaServerConfig();

        // For backward compatibility
        JsonXStream.getInstance().registerConverter(new V1AwareInstanceInfoConverter(), XStream.PRIORITY_VERY_HIGH);
        XmlXStream.getInstance().registerConverter(new V1AwareInstanceInfoConverter(), XStream.PRIORITY_VERY_HIGH);

        logger.info("Initializing the eureka client...");
        logger.info(eurekaServerConfig.getJsonCodecName());
        ServerCodecs serverCodecs = new DefaultServerCodecs(eurekaServerConfig);

        ApplicationInfoManager applicationInfoManager = null;

        if (eurekaClient == null) {
            EurekaInstanceConfig instanceConfig = isCloud(ConfigurationManager.getDeploymentContext())
                    ? new CloudInstanceConfig()
                    : new MyDataCenterInstanceConfig();

            applicationInfoManager = new ApplicationInfoManager(
                    instanceConfig, new EurekaConfigBasedInstanceInfoProvider(instanceConfig).get());

            EurekaClientConfig eurekaClientConfig = new DefaultEurekaClientConfig();
            eurekaClient = new DiscoveryClient(applicationInfoManager, eurekaClientConfig);
        } else {
            applicationInfoManager = eurekaClient.getApplicationInfoManager();
        }

        PeerAwareInstanceRegistry registry;
        if (isAws(applicationInfoManager.getInfo())) {
            registry = new AwsInstanceRegistry(
                    eurekaServerConfig,
                    eurekaClient.getEurekaClientConfig(),
                    serverCodecs,
                    eurekaClient
            );
            awsBinder = new AwsBinderDelegate(eurekaServerConfig, eurekaClient.getEurekaClientConfig(), registry, applicationInfoManager);
            awsBinder.start();
        } else {
            registry = new PeerAwareInstanceRegistryImpl(
                    eurekaServerConfig,
                    eurekaClient.getEurekaClientConfig(),
                    serverCodecs,
                    eurekaClient
            );
        }

        PeerEurekaNodes peerEurekaNodes = getPeerEurekaNodes(
                registry,
                eurekaServerConfig,
                eurekaClient.getEurekaClientConfig(),
                serverCodecs,
                applicationInfoManager
        );

        serverContext = new DefaultEurekaServerContext(
                eurekaServerConfig,
                serverCodecs,
                registry,
                peerEurekaNodes,
                applicationInfoManager
        );

        EurekaServerContextHolder.initialize(serverContext);

        serverContext.initialize();
        logger.info("Initialized server context");

        // Copy registry from neighboring eureka node
        int registryCount = registry.syncUp();
        registry.openForTraffic(applicationInfoManager, registryCount);

        // Register all monitoring statistics.
        EurekaMonitors.registerAllStats();
    }

init

    private void init() {
//设置为测试环境
        String env = ConfigurationManager.getConfigInstance().getString(
                EUREKA_ENVIRONMENT, TEST);
        ConfigurationManager.getConfigInstance().setProperty(
                ARCHAIUS_DEPLOYMENT_ENVIRONMENT, env);
//通常来说我们一个常数，都是会放在一个常数类中，使用config.test 来调用test配置项，但
//是eureka-server这里，使用了另外一种思想，人家没有用大量的常量，而是针对配置定义了一
//个接口，接口里通过方法暴露了大量的配置项获取的方法，你呢直接通过这个接口来获取你需要的配置项，即可。
//规定配置文件为eureka-server.properties
        String eurekaPropsFile = EUREKA_PROPS_FILE.get();
        try {
//配置管理器加载配置文件
            ConfigurationManager
                    .loadCascadedPropertiesFromResources(eurekaPropsFile);
        } catch (IOException e) {
            logger.warn(
                    "Cannot find the properties specified : {}. This may be okay if there are other environment "
                            + "specific properties or the configuration is installed with a different mechanism.",
                    eurekaPropsFile);
        }
    }