public interface SpringApplicationRunListener {
	/**
	 * 當(dāng)run方法第一次啟動(dòng)時(shí)立即調(diào)用，可用于非常早期的初始化
	 */
	default void starting() {
	}
	/**
	 * 在ApplicationContext創(chuàng)建之前，一旦環(huán)境environment準(zhǔn)備好就調(diào)用。
	 * @param environment the environment
	 */
	default void environmentPrepared(ConfigurableEnvironment environment) {
	}
	/**
	 * 在資源（可以理解為配置主類）被加載完成之前，一旦ApplicationContext被創(chuàng)建并準(zhǔn)備好就立馬調(diào)用，
	 * @param context the application context
	 */
	default void contextPrepared(ConfigurableApplicationContext context) {
	}
	/**
	 * 在資源加載完成之后，但在刷新之前調(diào)用
	 * @param context the application context
	 */
	default void contextLoaded(ConfigurableApplicationContext context) {
	}
	/**
	 * 上下文已刷新，應(yīng)用程序已啟動(dòng)，但是CommandLineRunner和ApplicationRunner尚未調(diào)用。
	 * @param context the application context.
	 * @since 2.0.0
	 */
	default void started(ConfigurableApplicationContext context) {
	}
	/**
	 * 當(dāng)ApplicationContext已經(jīng)refresh且所有的CommandLineRunner和ApplicationRunner都已被調(diào)用時(shí)，在run方法完成之前立即調(diào)用。
	 * @param context the application context.
	 * @since 2.0.0
	 */
	default void running(ConfigurableApplicationContext context) {
	}
	/**
	 * 在運(yùn)行應(yīng)用程序時(shí)發(fā)生故障時(shí)調(diào)用
	 * @param context 應(yīng)用程序上下文，可能為null(在應(yīng)用程序上下文創(chuàng)建之前)
	 * @param exception the failure
	 * @since 2.0.0
	 */
	default void failed(ConfigurableApplicationContext context, Throwable exception) {
	}

public class EventPublishingRunListener implements SpringApplicationRunListener, Ordered {
	//啟動(dòng)類實(shí)例對(duì)象
	private final SpringApplication application;
	//參數(shù)
	private final String[] args;
	//ApplicationListener監(jiān)聽器接口代理廣播類
	private final SimpleApplicationEventMulticaster initialMulticaster;
	public EventPublishingRunListener(SpringApplication application, String[] args) {
		this.application = application;
		this.args = args;
		this.initialMulticaster = new SimpleApplicationEventMulticaster();
    //獲取應(yīng)用程序的監(jiān)聽器類，并循環(huán)添加到代理類的監(jiān)聽器助手屬性對(duì)象中
		for (ApplicationListener<?> listener : application.getListeners()) {
			this.initialMulticaster.addApplicationListener(listener);
		}
	}
}

//監(jiān)聽器對(duì)象集合
private List<ApplicationListener<?>> listeners;

public SpringApplication(ResourceLoader resourceLoader, Class<?>... primarySources) {
		this.resourceLoader = resourceLoader;
		Assert.notNull(primarySources, "PrimarySources must not be null");
		this.primarySources = new LinkedHashSet<>(Arrays.asList(primarySources));
		this.webApplicationType = WebApplicationType.deduceFromClasspath();
  	//通過SPI方式初始化應(yīng)用程序初始化器
		setInitializers((Collection) getSpringFactoriesInstances(ApplicationContextInitializer.class));
		//通過SPI方式獲取ApplicationListener監(jiān)聽器
		setListeners((Collection) getSpringFactoriesInstances(ApplicationListener.class));
		this.mainApplicationClass = deduceMainApplicationClass();
	}

# Application Listeners
org.springframework.context.ApplicationListener=\
org.springframework.boot.ClearCachesApplicationListener,\
org.springframework.boot.builder.ParentContextCloserApplicationListener,\
org.springframework.boot.cloud.CloudFoundryVcapEnvironmentPostProcessor,\
org.springframework.boot.context.FileEncodingApplicationListener,\
org.springframework.boot.context.config.AnsiOutputApplicationListener,\
org.springframework.boot.context.config.ConfigFileApplicationListener,\
org.springframework.boot.context.config.DelegatingApplicationListener,\
org.springframework.boot.context.logging.ClasspathLoggingApplicationListener,\
org.springframework.boot.context.logging.LoggingApplicationListener,\
org.springframework.boot.liquibase.LiquibaseServiceLocatorApplicationListener

class SpringApplicationRunListeners {

	private final Log log;
	//存儲(chǔ)SpringApplicationRunListener監(jiān)聽器集合
	private final List<SpringApplicationRunListener> listeners;

	SpringApplicationRunListeners(Log log, Collection<? extends SpringApplicationRunListener> listeners) {
		this.log = log;
		this.listeners = new ArrayList<>(listeners);
	}
}

public ConfigurableApplicationContext run(String... args) {
		StopWatch stopWatch = new StopWatch();
		stopWatch.start();
		ConfigurableApplicationContext context = null;
		Collection<SpringBootExceptionReporter> exceptionReporters = new ArrayList<>();
		configureHeadlessProperty();
    //通過SPI方式獲取SpringApplicationRunListener監(jiān)聽器對(duì)象集合
		SpringApplicationRunListeners listeners = getRunListeners(args);
    //啟動(dòng)監(jiān)聽器，傳遞ApplicationStartingEvent事件
		listeners.starting();
		try {
			ApplicationArguments applicationArguments = new DefaultApplicationArguments(args);
      //environment準(zhǔn)備好之后調(diào)用監(jiān)聽器environmentPrepared方法
      //傳遞ApplicationEnvironmentPreparedEvent事件
			ConfigurableEnvironment environment = prepareEnvironment(listeners, applicationArguments);
			configureIgnoreBeanInfo(environment);
			Banner printedBanner = printBanner(environment);
			context = createApplicationContext();
			exceptionReporters = getSpringFactoriesInstances(SpringBootExceptionReporter.class,
					new Class[] { ConfigurableApplicationContext.class }, context);
      //資源加載之前調(diào)用監(jiān)聽器的contextPrepared方法，傳遞ApplicationContextInitializedEvent事件
      //資源加載之后，refresh方法調(diào)用之前調(diào)用監(jiān)聽器的contextLoaded方法，傳遞ApplicationPreparedEvent事件
			prepareContext(context, environment, listeners, applicationArguments, printedBanner);
			refreshContext(context);
			afterRefresh(context, applicationArguments);
			stopWatch.stop();
			if (this.logStartupInfo) {
				new StartupInfoLogger(this.mainApplicationClass).logStarted(getApplicationLog(), stopWatch);
			}
      //應(yīng)用程序refresh之后調(diào)用，傳遞ApplicationStartedEvent事件
			listeners.started(context);
			callRunners(context, applicationArguments);
		}
		catch (Throwable ex) {
      //應(yīng)用程序啟動(dòng)過程中出現(xiàn)異常調(diào)用failed方法
      //傳遞ApplicationFailedEvent事件
			handleRunFailure(context, ex, exceptionReporters, listeners);
			throw new IllegalStateException(ex);
		}
		try {
      //在應(yīng)用程序run方法運(yùn)行結(jié)束之前調(diào)用，傳遞ApplicationReadyEvent事件
			listeners.running(context);
		}
		catch (Throwable ex) {
			handleRunFailure(context, ex, exceptionReporters, null);
			throw new IllegalStateException(ex);
		}
		return context;
	}
	//通過SPI方式獲取SpringApplicationRunListener接口實(shí)現(xiàn)類，并創(chuàng)建SpringApplicationRunListeners集合類
	private SpringApplicationRunListeners getRunListeners(String[] args) {
		Class<?>[] types = new Class<?>[] { SpringApplication.class, String[].class };
		return new SpringApplicationRunListeners(logger,
				getSpringFactoriesInstances(SpringApplicationRunListener.class, types, this, args));
	}

# Run Listeners
org.springframework.boot.SpringApplicationRunListener=\
org.springframework.boot.context.event.EventPublishingRunListener