深入剖析Springboot启动原理的底层源码，再也不怕面试官问了！

﹏ヽ暗。殇╰゛Y 2023-07-17 02:48 13阅读 0赞

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>   
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>   
> `用知识改变命运，让我们的家人过上更好的生活`。

***相关文章：***

[【SpringBoot 系列】史上最全的springboot学习教程][SpringBoot _springboot]

--------------------

<table> 
 <tbody> 
  <tr> 
   <td>本文通过剖析源码，对Spring Boot(基于2.x版本)的启动过程进行深入的理解 </td> 
  </tr> 
 </tbody> 
</table>

### 文章目录 ###

*   *   *  一、入口类及其源码剖析
         *  二、实例化SpringApplication对象的源码剖析
         *   *  1. 设置初始化器(Initializer)
             *  2. 设置监听器
             *  3. 推断主应用入口类
         *  三、run() 方法源码剖析
         *   *  1. 开启计时器
             *  2. 设置系统属性的值
             *  3. 监听器
             *  4. 初始化默认参数
             *  5.创建 Spring 环境
             *  6. 打印器
             *  7. 创建Spring应用上下文
             *  8. 实例化异常报告器
             *  9. Spring上下文前置处理
             *  10. Spring上下文刷新
             *  11. Spring上下文后置处理
             *  12. 停止计时器
             *  13. 发布Spring上下文启动完成事件
             *  14. 执行所有 Runner 运行器
             *  15. 发布Spring上下文就绪事件

### 一、入口类及其源码剖析 ###

*入口类*

@SpringBootApplication
    public class DevServiceApplication { 
    
        public static void main(String[] args) { 
            SpringApplication.run(DevServiceApplication.class,args);
        }
    }

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzU3MDM2Nw_size_16_color_FFFFFF_t_70]  
***首先从注解入手，进行分析：***

@SpringBootApplication 注解

> Spring Boot应用标注在某个类上说明这个类是SpringBoot的主配置类，SpringBoot就应该运行这个类的main方法来启动SpringBoot应用

***`源码剖析`***

@Target(ElementType.TYPE)
    @Retention(RetentionPolicy.RUNTIME)
    @Documented
    @Inherited
    @SpringBootConfiguration
    @EnableAutoConfiguration
    @ComponentScan(excludeFilters = {  @Filter(type = FilterType.CUSTOM, classes = TypeExcludeFilter.class),
    		@Filter(type = FilterType.CUSTOM, classes = AutoConfigurationExcludeFilter.class) })
    public @interface SpringBootApplication {

> 从源码可以看出，这个注解是@SpringBootConfiguration，@EnableAutoConfiguration以及@ComponentScan这三个注解的组合

① @**SpringBootConfiguration**

*Spring Boot的配置类；标注在某个类上，表示一个类提供了Spring Boot应用程序*

@Target(ElementType.TYPE)
    @Retention(RetentionPolicy.RUNTIME)
    @Documented
    @Configuration
    public @interface SpringBootConfiguration {

@**Configuration**:配置类上来标注这个注解；

@Target(ElementType.TYPE)
    @Retention(RetentionPolicy.RUNTIME)
    @Documented
    @Component
    public @interface Configuration {

***注意***：

配置类相当于配置文件；配置类也是容器中的一个组件，它使用了@Component这个注解。

② @**EnableAutoConfiguration**

*告诉SpringBoot开启自动配置功能，这样自动配置才能生效*  
借助@import,扫描并实例化满足条件的自动配置的bean，然后加载到IOC容器中

@Target(ElementType.TYPE)
    @Retention(RetentionPolicy.RUNTIME)
    @Documented
    @Inherited
    @AutoConfigurationPackage
    @Import(AutoConfigurationImportSelector.class)
    public @interface EnableAutoConfiguration { 
    
    	String ENABLED_OVERRIDE_PROPERTY = "spring.boot.enableautoconfiguration";
    
    	/** * Exclude specific auto-configuration classes such that they will never be applied. * @return the classes to exclude */
    	Class<?>[] exclude() default { };
    
    	/** * Exclude specific auto-configuration class names such that they will never be * applied. * @return the class names to exclude * @since 1.3.0 */
    	String[] excludeName() default { };
    
    }

@**AutoConfigurationPackage**：自动配置包  
@**Import**(EnableAutoConfigurationImportSelector.class)：给容器中导入组件

![在这里插入图片描述][20200318154358656.png_x-oss-process_image]

> 使用@EnableAutoConfiguration  
> 这个注解开启自动扫描，然后使用select选择挑选满足条件的文件，并且使用SpringFactoriesLoader进行实例化。最后加载到IOC容器里面，即ApplicationContext中。

③ @**ComponentScan**

@ComponentScan就是自动扫描并加载符合条件的组件（比如@Component和@Repository等）或者bean定义，最终将这些bean定义加载到IOC容器中去 。

### 二、实例化SpringApplication对象的源码剖析 ###

***`源码剖析`***

/** * Create a new {@link SpringApplication} instance. The application context will load * beans from the specified primary sources (see {@link SpringApplication class-level} * documentation for details. The instance can be customized before calling * {@link #run(String...)}. * @param resourceLoader the resource loader to use * @param primarySources the primary bean sources * @see #run(Class, String[]) * @see #setSources(Set) */
    @SuppressWarnings({  "unchecked", "rawtypes" })
    public SpringApplication(ResourceLoader resourceLoader, Class<?>... primarySources) { 
    	// 初始化资源加载器
    	this.resourceLoader = resourceLoader;
    	// 资源加载类不能为 null
    	Assert.notNull(primarySources, "PrimarySources must not be null");
    	// 初始化加载资源类集合并去重
    	this.primarySources = new LinkedHashSet<>(Arrays.asList(primarySources));
    	// 推断应用程序是不是web应用
    	this.webApplicationType = WebApplicationType.deduceFromClasspath();
    	// 设置初始化器(Initializer)
    	setInitializers((Collection) getSpringFactoriesInstances(ApplicationContextInitializer.class));
    	// 设置监听器 
    	setListeners((Collection) getSpringFactoriesInstances(ApplicationListener.class));
    	// 推断出主应用入口类
    	this.mainApplicationClass = deduceMainApplicationClass();
    }

*其中，在推断应用程序是不是web应用的时候调用了deduceFromClasspath() 方法*

***`源码剖析`***

static WebApplicationType deduceFromClasspath() { 
    		if (ClassUtils.isPresent(WEBFLUX_INDICATOR_CLASS, null) && !ClassUtils.isPresent(WEBMVC_INDICATOR_CLASS, null)
    				&& !ClassUtils.isPresent(JERSEY_INDICATOR_CLASS, null)) { 
    			// springboot2.0提出的响应式web应用 
    			return WebApplicationType.REACTIVE;
    		}
    		for (String className : SERVLET_INDICATOR_CLASSES) { 
    			// 如果两个包路径都没有的话，就是普通应用
    			if (!ClassUtils.isPresent(className, null)) { 
    				// 普通的应用
    				return WebApplicationType.NONE;
    			}
    		}
    		// 其实最后返回的就是这个servlet，因为是web应用
    		return WebApplicationType.SERVLET;
    	}

#### 1. 设置初始化器(Initializer) ####

initializers 是 SpringApplication 中的一个实例属性

***`源码剖析`***

/** * Sets the {@link ApplicationContextInitializer} that will be applied to the Spring * {@link ApplicationContext}. * @param initializers the initializers to set */
    public void setInitializers(Collection<? extends ApplicationContextInitializer<?>> initializers) { 
    	this.initializers = new ArrayList<>(initializers);
    }

initailizer实现了ApplicationContextInitializer接口

***`源码剖析`***

/** * Callback interface for initializing a Spring {@link ConfigurableApplicationContext} * prior to being {@linkplain ConfigurableApplicationContext#refresh() refreshed}. * * <p>Typically used within web applications that require some programmatic initialization * of the application context. For example, registering property sources or activating * profiles against the {@linkplain ConfigurableApplicationContext#getEnvironment() * context's environment}. See {@code ContextLoader} and {@code FrameworkServlet} support * for declaring a "contextInitializerClasses" context-param and init-param, respectively. * * <p>{@code ApplicationContextInitializer} processors are encouraged to detect * whether Spring's {@link org.springframework.core.Ordered Ordered} interface has been * implemented or if the @{@link org.springframework.core.annotation.Order Order} * annotation is present and to sort instances accordingly if so prior to invocation. * * @author Chris Beams * @since 3.1 * @param <C> the application context type * @see org.springframework.web.context.ContextLoader#customizeContext * @see org.springframework.web.context.ContextLoader#CONTEXT_INITIALIZER_CLASSES_PARAM * @see org.springframework.web.servlet.FrameworkServlet#setContextInitializerClasses * @see org.springframework.web.servlet.FrameworkServlet#applyInitializers */
    public interface ApplicationContextInitializer<C extends ConfigurableApplicationContext> { 
    
    	/** * Initialize the given application context. * @param applicationContext the application to configure */
    	 // 把初始化的ApplicationContextInitializer实现类加载到SpringApplication中
    	void initialize(C applicationContext);
    
    }

***总结：***

>  *  ApplicationContextInitializer接口的作用，在Spring上下文被刷新之前进行初始化的操作。典型地比如在Web应用中，注册Property Sources或者是激活Profiles。Property Sources比较好理解，就是配置文件。Profiles是Spring为了在不同环境下(如DEV，TEST，PRODUCTION等)，加载不同的配置项而抽象出来的一个实体。
>  *  调用initialize()方法，把初始化的ApplicationContextInitializer实现加载到SpringApplication中

通过getSpringFactoriesInstances(  
ApplicationContextInitializer.class)方法获得实现类

***`源码剖析`***

private <T> Collection<T> getSpringFactoriesInstances(Class<T> type) { 
    	return getSpringFactoriesInstances(type, new Class<?>[] { });
    }
    
    private <T> Collection<T> getSpringFactoriesInstances(Class<T> type, Class<?>[] parameterTypes, Object... args) { 
    	ClassLoader classLoader = getClassLoader();
    	// Use names and ensure unique to protect against duplicates
    	// 使用 Set保存names
    	Set<String> names = new LinkedHashSet<>(SpringFactoriesLoader.loadFactoryNames(type, classLoader));
    	// 根据names进行实例化
    	List<T> instances = createSpringFactoriesInstances(type, parameterTypes, classLoader, args, names);
    	// 对实例进行排序
    	AnnotationAwareOrderComparator.sort(instances);
    	return instances;
    }

#### 2. 设置监听器 ####

***`源码剖析`***

/** * Sets the {@link ApplicationListener}s that will be applied to the SpringApplication * and registered with the {@link ApplicationContext}. * @param listeners the listeners to set */
    public void setListeners(Collection<? extends ApplicationListener<?>> listeners) { 
    	this.listeners = new ArrayList<>(listeners);
    }

*继承了ApplicationListener()接口*

***`源码剖析`***

/** * Interface to be implemented by application event listeners. * * <p>Based on the standard {@code java.util.EventListener} interface * for the Observer design pattern. * * <p>As of Spring 3.0, an {@code ApplicationListener} can generically declare * the event type that it is interested in. When registered with a Spring * {@code ApplicationContext}, events will be filtered accordingly, with the * listener getting invoked for matching event objects only. * * @author Rod Johnson * @author Juergen Hoeller * @param <E> the specific {@code ApplicationEvent} subclass to listen to * @see org.springframework.context.ApplicationEvent * @see org.springframework.context.event.ApplicationEventMulticaster * @see org.springframework.context.event.EventListener */
    @FunctionalInterface
    public interface ApplicationListener<E extends ApplicationEvent> extends EventListener { 
    
    	/** * Handle an application event. * @param event the event to respond to */
    	void onApplicationEvent(E event);
    
    }

***总结***：

> 在这里使用到了观察者模式，有一个被观察者和许多观察者，当被观察者的状态发生改变时，要通知所有的观察者做一些操作。

#### 3. 推断主应用入口类 ####

***`源码剖析`***

private Class<?> deduceMainApplicationClass() { 
    	try { 
    		// 构造一个异常类
    		StackTraceElement[] stackTrace = new RuntimeException().getStackTrace();
    		for (StackTraceElement stackTraceElement : stackTrace) { 
    			// 通过main的栈帧推断出入口类的名字
    			if ("main".equals(stackTraceElement.getMethodName())) { 
    				return Class.forName(stackTraceElement.getClassName());
    			}
    		}
    	}
    	catch (ClassNotFoundException ex) { 
    		// Swallow and continue
    	}
    	return null;
    }

### 三、run() 方法源码剖析 ###

***`源码剖析`***

/** * Run the Spring application, creating and refreshing a new * {@link ApplicationContext}. * @param args the application arguments (usually passed from a Java main method) * @return a running {@link ApplicationContext} */
    public ConfigurableApplicationContext run(String... args) { 
    	// 记时器，统计应用启动的时间
    	StopWatch stopWatch = new StopWatch();
    	stopWatch.start();
    	// 初始化应用上下文和异常报告集合
    	ConfigurableApplicationContext context = null;
    	// SpringBootExceptionReporter 是异常处理器，启动的时候通过它把异常信息展示出来
    	Collection<SpringBootExceptionReporter> exceptionReporters = new ArrayList<>();
    	 // 设置系统属性java.awt.headless的值，默认为true
    	configureHeadlessProperty();
    	// 监听器，SpringApplicationRunListeners实际上是一个集合
    	SpringApplicationRunListeners listeners = getRunListeners(args);
    	// 回调所有的获取SpringApplicationRunListener.starting()方法
    	listeners.starting();
    	try { 
    		// 初始化默认参数
    		ApplicationArguments applicationArguments = new DefaultApplicationArguments(args);
    		// 准备 Spring 环境
    		ConfigurableEnvironment environment = prepareEnvironment(listeners, applicationArguments);
    		// 创建环境完成后回调，配置bean
    		configureIgnoreBeanInfo(environment);
    		// 打印器，springboot启动的时候会打印springboot的标志以及对应的版本
    		Banner printedBanner = printBanner(environment);
    		// 创建Spring应用上下文，来决定创建web的ioc还是普通的ioc
    		context = createApplicationContext();
    		// 实例化异常报告器
    		exceptionReporters = getSpringFactoriesInstances(SpringBootExceptionReporter.class,
    				new Class[] {  ConfigurableApplicationContext.class }, context);
    		//准备上下文环境
            // Spring上下文前置处理
    		prepareContext(context, environment, listeners, applicationArguments, printedBanner);
    		// prepareContext运行完成以后回调所有的SpringApplicationRunListener的contextLoaded（）；
    		// Spring上下文刷新，表示刷新完成，进行后续的一些操作
    		refreshContext(context);
            // Spring上下文后置处理
    		afterRefresh(context, applicationArguments);
    		// 停止计时器
    		stopWatch.stop();
    		// 输出日志记录的类名、时间信息
    		if (this.logStartupInfo) { 
    			new StartupInfoLogger(this.mainApplicationClass).logStarted(getApplicationLog(), stopWatch);
    		}
    		// 发布应用上下文启动完成事件
    		listeners.started(context);
    		// 执行所有 Runner 运行器
    		callRunners(context, applicationArguments);
    	}
    	catch (Throwable ex) { 
    		handleRunFailure(context, ex, exceptionReporters, listeners);
    		throw new IllegalStateException(ex);
    	}
    
    	try { 
    		// 发布应用上下文就绪事件
    		listeners.running(context);
    	}
    	catch (Throwable ex) { 
    		handleRunFailure(context, ex, exceptionReporters, null);
    		throw new IllegalStateException(ex);
    	}
    	// 返回应用上下文
    	return context;
    }

#### 1. 开启计时器 ####

开启计时器，用来统计应用启动的时间

public void start() throws IllegalStateException { 
    		// 传入一个空字符串作为当前任务的名称
            this.start("");
        }
    
        public void start(String taskName) throws IllegalStateException { 
            if (this.currentTaskName != null) { 
            	// 如果当前任务名字不为空，抛出异常
                throw new IllegalStateException("Can't start StopWatch: it's already running");
            } else { 
            	// 否则，记录当前任务的开始时间
                this.currentTaskName = taskName;
                this.startTimeNanos = System.nanoTime();
            }
        }

>  *  首先，传入一个空字符串作为当前任务的名称
>  *  其次，判断当前任务名是否空，如果为空，则记录当前应用启动的开始时间

#### 2. 设置系统属性的值 ####

系统属性的值默认是true，系统属性的值来源于System.getProperty()。

private void configureHeadlessProperty() { 
    		System.setProperty(SYSTEM_PROPERTY_JAVA_AWT_HEADLESS,
    				System.getProperty(SYSTEM_PROPERTY_JAVA_AWT_HEADLESS, Boolean.toString(this.headless)));
    	}

#### 3. 监听器 ####

private SpringApplicationRunListeners getRunListeners(String[] args) { 
    		// 类加载对应的监听器
    		Class<?>[] types = new Class<?>[] {  SpringApplication.class, String[].class };
    		// 创建SpringApplicationRunListener实例
    		return new SpringApplicationRunListeners(logger,
    				getSpringFactoriesInstances(SpringApplicationRunListener.class, types, this, args));
    	}

#### 4. 初始化默认参数 ####

ApplicationArguments applicationArguments = new DefaultApplicationArguments(args);

#### 5.创建 Spring 环境 ####

private ConfigurableEnvironment prepareEnvironment(
            SpringApplicationRunListeners listeners,
            ApplicationArguments applicationArguments) { 
        // 获取环境。如果存在就直接返回，否则先创建一个再返回
        ConfigurableEnvironment environment = getOrCreateEnvironment();
        // 配置环境
        configureEnvironment(environment, applicationArguments.getSourceArgs());
        // 准备监听器环境
        listeners.environmentPrepared(environment);
        // 将环境绑定到SpringApplication上面
        bindToSpringApplication(environment);
        // 如果不是web应用环境，将环境转换成StandardEnvironment
        if (this.webApplicationType == WebApplicationType.NONE) { 
            environment = new EnvironmentConverter(getClassLoader())
                    .convertToStandardEnvironmentIfNecessary(environment);
        }
        ConfigurationPropertySources.attach(environment);
        // 返回环境
        return environment;
    }

***总结***：

>  *  获取环境。如果存在就直接返回，否则先创建一个再返回
>  *  配置环境
>  *  准备监听器环境
>  *  将环境绑定到SpringApplication上面
>  *  如果不是web应用环境，将环境转换成StandardEnvironment
>  *  最后返回环境

#### 6. 打印器 ####

springboot启动的时候会打印springboot的标志以及对应的版本

private Banner printBanner(ConfigurableEnvironment environment) { 
    		if (this.bannerMode == Banner.Mode.OFF) { 
    			return null;
    		}
    		ResourceLoader resourceLoader = (this.resourceLoader != null) ? this.resourceLoader
    				: new DefaultResourceLoader(getClassLoader());
    		SpringApplicationBannerPrinter bannerPrinter = new SpringApplicationBannerPrinter(resourceLoader, this.banner);
    		if (this.bannerMode == Mode.LOG) { 
    			return bannerPrinter.print(environment, this.mainApplicationClass, logger);
    		}
    		return bannerPrinter.print(environment, this.mainApplicationClass, System.out);
    	}

#### 7. 创建Spring应用上下文 ####

protected ConfigurableApplicationContext createApplicationContext() { 
    	// 首先进行判断有没有指定的实现类
    	Class<?> contextClass = this.applicationContextClass;
    	// 如果没有，则根据应用类型选择
    	if (contextClass == null) { 
    		try { 
    			// 根据webApplicationType的类型去反射创建ConfigurableApplicationContext的具体实例
    			switch (this.webApplicationType) { 
    			case SERVLET:
    				contextClass = Class.forName(DEFAULT_SERVLET_WEB_CONTEXT_CLASS);
    				break;
    			case REACTIVE:
    				contextClass = Class.forName(DEFAULT_REACTIVE_WEB_CONTEXT_CLASS);
    				break;
    			default:
    				contextClass = Class.forName(DEFAULT_CONTEXT_CLASS);
    			}
    		}
    		catch (ClassNotFoundException ex) { 
    			throw new IllegalStateException(
    					"Unable create a default ApplicationContext, please specify an ApplicationContextClass", ex);
    		}
    	}
    	// 通过反射，得到创建的对象
    	return (ConfigurableApplicationContext) BeanUtils.instantiateClass(contextClass);
    }

***总结***：

>  *  首先进行判断有没有指定的实现类； 如果没有，则根据应用类型选择；
>  *  根据webApplicationType的类型去反射创建ConfigurableApplicationContext的具体实例；
>  *  最后通过反射，得到创建的对象

对于Web应用，上下文类型是DEFAULT\_WEB\_CONTEXT\_CLASS。

#### 8. 实例化异常报告器 ####

用 getSpringFactoriesInstances() 方法，获取配置的异常类名称，并实例化所有的异常类。

***`源码剖析`***

private <T> Collection<T> getSpringFactoriesInstances(Class<T> type, Class<?>[] parameterTypes, Object... args) { 
    	ClassLoader classLoader = getClassLoader();
    	// Use names and ensure unique to protect against duplicates
    	// 使用名称并确保唯一，以防止重复
    	Set<String> names = new LinkedHashSet<>(SpringFactoriesLoader.loadFactoryNames(type, classLoader));
    	List<T> instances = createSpringFactoriesInstances(type, parameterTypes, classLoader, args, names);
    	AnnotationAwareOrderComparator.sort(instances);
    	return instances;
    }

#### 9. Spring上下文前置处理 ####

***`源码剖析`***

private void prepareContext(ConfigurableApplicationContext context, ConfigurableEnvironment environment,
    			SpringApplicationRunListeners listeners, ApplicationArguments applicationArguments, Banner printedBanner) { 
    	// 给IOC容器设置一些环境属性
    	context.setEnvironment(environment);
    	// 给IOC容器注册一些组件
    	postProcessApplicationContext(context);
    	// 调用初始化方法
    	applyInitializers(context);
    	// 监听器，触发contextPrepared 事件
    	listeners.contextPrepared(context);
    	// 记录启动过程中的日志
    	if (this.logStartupInfo) { 
    		logStartupInfo(context.getParent() == null);
    		logStartupProfileInfo(context);
    	}
    	// Add boot specific singleton beans
    	// 添加特定的单例beans
    	ConfigurableListableBeanFactory beanFactory = context.getBeanFactory();
    	beanFactory.registerSingleton("springApplicationArguments", applicationArguments);
    	if (printedBanner != null) { 
    		beanFactory.registerSingleton("springBootBanner", printedBanner);
    	}
    	if (beanFactory instanceof DefaultListableBeanFactory) { 
    		((DefaultListableBeanFactory) beanFactory)
    				.setAllowBeanDefinitionOverriding(this.allowBeanDefinitionOverriding);
    	}
    	if (this.lazyInitialization) { 
    		context.addBeanFactoryPostProcessor(new LazyInitializationBeanFactoryPostProcessor());
    	}
    	// Load the sources
    	// 加载所有资源
    	Set<Object> sources = getAllSources();
    	Assert.notEmpty(sources, "Sources must not be empty");
    	// 加载启动类，将启动类注入到容器中去
    	load(context, sources.toArray(new Object[0]));
    	// 触发contextLoaded 事件
    	listeners.contextLoaded(context);
    }

#### 10. Spring上下文刷新 ####

刷新完成以后，会进行后续的一些操作

***`源码剖析`***

private void refreshContext(ConfigurableApplicationContext context) { 
    	// 调用父类的refresh操作
    	refresh(context);
    	if (this.registerShutdownHook) { 
    		try { 
    			// 注册一个关闭容器时的钩子函数，在JVM关机的时候关闭这个上下文。
    			context.registerShutdownHook();
    		}
    		catch (AccessControlException ex) { 
    			// Not allowed in some environments.
    		}
    	}
    }

*调用了registerShutdownHook()方法*

/** * Register a shutdown hook {@linkplain Thread#getName() named} * {@code SpringContextShutdownHook} with the JVM runtime, closing this * context on JVM shutdown unless it has already been closed at that time. * <p>Delegates to {@code doClose()} for the actual closing procedure. * @see Runtime#addShutdownHook * @see ConfigurableApplicationContext#SHUTDOWN_HOOK_THREAD_NAME * @see #close() * @see #doClose() */
    @Override
    public void registerShutdownHook() { 
    	if (this.shutdownHook == null) { 
    		// No shutdown hook registered yet.
    		this.shutdownHook = new Thread(SHUTDOWN_HOOK_THREAD_NAME) { 
    			@Override
    			public void run() { 
    				synchronized (startupShutdownMonitor) { 
    					// 调用doClose方法，进行容器销毁时的清理工作
    					doClose();
    				}
    			}
    		};
    		Runtime.getRuntime().addShutdownHook(this.shutdownHook);
    	}
    }

#### 11. Spring上下文后置处理 ####

在Spring容器刷新上下文后进行调用，依次调用注册的Runners。

/** * Called after the context has been refreshed. * @param context the application context * @param args the application arguments */
    protected void afterRefresh(ConfigurableApplicationContext context, ApplicationArguments args) { 
    }
    
    private void callRunners(ApplicationContext context, ApplicationArguments args) { 
    	List<Object> runners = new ArrayList<>();
    	runners.addAll(context.getBeansOfType(ApplicationRunner.class).values());
    	runners.addAll(context.getBeansOfType(CommandLineRunner.class).values());
    	AnnotationAwareOrderComparator.sort(runners);
    	// CommandLineRunner、ApplicationRunner 这两个接口，是在容器启动成功后的最后一步进行回调
    	for (Object runner : new LinkedHashSet<>(runners)) { 
    		if (runner instanceof ApplicationRunner) { 
    			callRunner((ApplicationRunner) runner, args);
    		}
    		if (runner instanceof CommandLineRunner) { 
    			callRunner((CommandLineRunner) runner, args);
    		}
    	}
    }

CommandLineRunner、ApplicationRunner 这两个接口，是在容器启动成功后的最后一步进行回调

#### 12. 停止计时器 ####

做计时监听器停止操作，并统计一些任务执行信息

public void stop() throws IllegalStateException { 
        if (this.currentTaskName == null) { 
            throw new IllegalStateException("Can't stop StopWatch: it's not running");
        } else { 
            long lastTime = System.nanoTime() - this.startTimeNanos;
            this.totalTimeNanos += lastTime;
            this.lastTaskInfo = new StopWatch.TaskInfo(this.currentTaskName, lastTime);
            if (this.keepTaskList) { 
                this.taskList.add(this.lastTaskInfo);
            }
    
            ++this.taskCount;
            this.currentTaskName = null;
        }
    }

#### 13. 发布Spring上下文启动完成事件 ####

void started(ConfigurableApplicationContext context) { 
    	for (SpringApplicationRunListener listener : this.listeners) { 
    		listener.started(context);
    	}
    }

#### 14. 执行所有 Runner 运行器 ####

private void callRunners(ApplicationContext context, ApplicationArguments args) { 
    	List<Object> runners = new ArrayList<>();
    	runners.addAll(context.getBeansOfType(ApplicationRunner.class).values());
    	runners.addAll(context.getBeansOfType(CommandLineRunner.class).values());
    	AnnotationAwareOrderComparator.sort(runners);
    	for (Object runner : new LinkedHashSet<>(runners)) { 
    		if (runner instanceof ApplicationRunner) { 
    			callRunner((ApplicationRunner) runner, args);
    		}
    		if (runner instanceof CommandLineRunner) { 
    			callRunner((CommandLineRunner) runner, args);
    		}
    	}
    }

#### 15. 发布Spring上下文就绪事件 ####

void running(ConfigurableApplicationContext context) { 
    	for (SpringApplicationRunListener listener : this.listeners) { 
    		listener.running(context);
    	}
    }

触发所有 SpringApplicationRunListener 监听器的 running 事件的方法。

--------------------

***由于水平有限，本博客难免有不足，恳请各位大佬不吝赐教！***

[SpringBoot _springboot]: https://blog.csdn.net/weixin_43570367/article/details/104213404
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