SpringApplication之run基本流程

核心方法run

SpringApplication.run(DemoApplication.class, args)
-->
	public static ConfigurableApplicationContext run(Class<?>[] primarySources, String[] args) {
		return new SpringApplication(primarySources).run(args);
	}
-->
	public SpringApplication(Class<?>... primarySources) {
		this(null, primarySources);
	}
-->
	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();
		//從spring.factories文件中加載初始化一些ApplicationContextInitializer
		setInitializers((Collection) getSpringFactoriesInstances(ApplicationContextInitializer.class)); 
		//從spring.factories文件中加載初始化一些ApplicationListener
		setListeners((Collection) getSpringFactoriesInstances(ApplicationListener.class));
		this.mainApplicationClass = deduceMainApplicationClass();
	}
/* 
1.setInitializers。	private List<ApplicationContextInitializer<?>> initializers;
# Application Context Initializers
org.springframework.context.ApplicationContextInitializer=\
org.springframework.boot.context.ConfigurationWarningsApplicationContextInitializer,\
org.springframework.boot.context.ContextIdApplicationContextInitializer,\
org.springframework.boot.context.config.DelegatingApplicationContextInitializer,\
org.springframework.boot.web.context.ServerPortInfoApplicationContextInitializer

2.setInitializers   private List<ApplicationListener<?>> listeners;
# Application Listeners
org.springframework.context.ApplicationListener=\
org.springframework.boot.ClearCachesApplicationListener,\
org.springframework.boot.builder.ParentContextCloserApplicationListener,\
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

*/
--> 最終調用
	public ConfigurableApplicationContext run(String... args) {
		StopWatch stopWatch = new StopWatch();
		stopWatch.start();
		ConfigurableApplicationContext context = null;
		Collection<SpringBootExceptionReporter> exceptionReporters = new ArrayList<>();
		configureHeadlessProperty();
		// 啓動springboot 事件監聽器，同上，從文件配置spring.factories中加載
		SpringApplicationRunListeners listeners = getRunListeners(args);
		listeners.starting(); // 觸發starting事件
		try {
			ApplicationArguments applicationArguments = new DefaultApplicationArguments(args); //創建應用程序的一些參數
			//環境參數的一些準備工作
			//listeners.environmentPrepared
			ConfigurableEnvironment environment = prepareEnvironment(listeners, applicationArguments); 
			configureIgnoreBeanInfo(environment);
			Banner printedBanner = printBanner(environment); //打印banner
			 //創建applicationcontext，這裏創建的是AnnotationConfigReactiveWebServerApplicationContext
			//listeners.contextPrepared(context);
			//調用構造器中加載的ApplicationContextInitializer.initialize(context)
			//listeners.contextLoaded(context);
			context = createApplicationContext();
			exceptionReporters = getSpringFactoriesInstances(SpringBootExceptionReporter.class,
					new Class[] { ConfigurableApplicationContext.class }, context);
			//註冊一些bean給容器管理如：printedBanner ApplicationArguments，並給context設置一些屬性
			prepareContext(context, environment, listeners, applicationArguments, printedBanner);
			//調用context的refresh函數，並設置shutdownhook，註冊ContextClosedEvent
			//關閉beanfactory，webserver等
			refreshContext(context);
			//空函數 do nothing
			afterRefresh(context, applicationArguments);
			stopWatch.stop();
			if (this.logStartupInfo) {
				new StartupInfoLogger(this.mainApplicationClass).logStarted(getApplicationLog(), stopWatch);
			}
			//context成功啓動
			listeners.started(context);
			//
			callRunners(context, applicationArguments);
		}
		catch (Throwable ex) {
			handleRunFailure(context, ex, exceptionReporters, listeners);
			throw new IllegalStateException(ex);
		}

		try {
			//發佈context運行中事件
			listeners.running(context);
		}
		catch (Throwable ex) {
			handleRunFailure(context, ex, exceptionReporters, null);
			throw new IllegalStateException(ex);
		}
		return context;
	}