<parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.5.1</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>

<dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

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

public static ConfigurableApplicationContext run(Class<?> primarySource, String... args) {
		return run(new Class<?>[] { primarySource }, args);
	}

public static ConfigurableApplicationContext run(Class<?>[] primarySources, String[] args) {
   return new SpringApplication(primarySources).run(args);
}

public SpringApplication(Class<?>... primarySources) {
		this(null, primarySources);
	}

@SuppressWarnings({ "unchecked", "rawtypes" })
public SpringApplication(ResourceLoader resourceLoader, Class<?>... primarySources) {
   ......
   //本次不相關(guān)的代碼全部省略掉，只保留相關(guān)代碼
   //這里的 this.webApplicationType=WebApplicationType.SERVLET， 我們來分析下這個(gè)代碼的具體的執(zhí)行賦值
   this.webApplicationType = WebApplicationType.deduceFromClasspath();
   ......
}

//這個(gè)方法主要是在當(dāng)前類路徑下查找指定的class類是否存在，返回對飲枚舉類型
	static WebApplicationType deduceFromClasspath() {
	// WEBMVC_INDICATOR_CLASS = "org.springframework.web.servlet.DispatcherServlet";
	
	//我們通過pom文件引入spring-boot-starter-web，會(huì)簡介引入spring-webmvc,上面這個(gè)類就在這個(gè)webmvc中，所以不會(huì)進(jìn)入這個(gè)if分支
		if (ClassUtils.isPresent(WEBFLUX_INDICATOR_CLASS, null) && !ClassUtils.isPresent(WEBMVC_INDICATOR_CLASS, null)
				&& !ClassUtils.isPresent(JERSEY_INDICATOR_CLASS, null)) {
			return WebApplicationType.REACTIVE;
		}
	//SERVLET_INDICATOR_CLASSES = { "javax.servlet.Servlet",
			"org.springframework.web.context.ConfigurableWebApplicationContext" }
	//javax.servlet.Servlet這個(gè)類存在于tomcat-embed-core中
    //org.springframework.web.context.ConfigurableWebApplicationContext這個(gè)類存在于spring-web中
    //這兩個(gè)jar都是由spring-boot-starter-web間接引入的，所以也不會(huì)走這個(gè)分支
		for (String className : SERVLET_INDICATOR_CLASSES) {
			if (!ClassUtils.isPresent(className, null)) {
				return WebApplicationType.NONE;
			}
		}
		//所以會(huì)從這里返回
		return WebApplicationType.SERVLET;
	}

public ConfigurableApplicationContext run(String... args) {
		.......
		try {
			......
			//我們來看這個(gè)context的創(chuàng)建，context=new AnnotationConfigServletWebServerApplicationContext()下面來具體看這塊的執(zhí)行
			context = createApplicationContext();
		    ......
		    //后續(xù)幾個(gè)部分會(huì)來說明這個(gè)方法
			refreshContext(context);
			......
		}
		catch (Throwable ex) {
			......
		}

		try {
		.......
		}
		catch (Throwable ex) {
		.......
		}
		return context;
	}

protected ConfigurableApplicationContext createApplicationContext() {
		//這里的this.webApplicationType就是上面的WebApplicationType.SERVLET
		return this.applicationContextFactory.create(this.webApplicationType);
	}

//最終會(huì)調(diào)用到這個(gè)lambda表達(dá)式，入?yún)⒕褪巧厦娴腤ebApplicationType.SERVLET
	ApplicationContextFactory DEFAULT = (webApplicationType) -> {
		try {
			switch (webApplicationType) {
			case SERVLET:
				//會(huì)從這里返回
				return new AnnotationConfigServletWebServerApplicationContext();
			case REACTIVE:
				return new AnnotationConfigReactiveWebServerApplicationContext();
			default:
				return new AnnotationConfigApplicationContext();
			}
		}
		catch (Exception ex) {
			throw new IllegalStateException("Unable create a default ApplicationContext instance, "
					+ "you may need a custom ApplicationContextFactory", ex);
		}
	};

public ConfigurableApplicationContext run(String... args) {
		.......
		try {
			......
			//上面已經(jīng)對context做過了講解，context=new AnnotationConfigServletWebServerApplicationContext()
			context = createApplicationContext();
		    ......
		    //下面來看這個(gè)方法
			refreshContext(context);
			......
		}
		catch (Throwable ex) {
			......
		}

		try {
		.......
		}
		catch (Throwable ex) {
		.......
		}
		return context;
	}

private void refreshContext(ConfigurableApplicationContext context) {
		if (this.registerShutdownHook) {
			shutdownHook.registerApplicationContext(context);
		}
		refresh(context);
	}

protected void refresh(ConfigurableApplicationContext applicationContext) {
        //這里的applicationContext就是AnnotationConfigServletWebServerApplicationContext的對象，由于這個(gè)類沒有refresh方法，會(huì)跳轉(zhuǎn)到它的父類ServletWebServerApplicationContext的方法中去,我們繼續(xù)點(diǎn)進(jìn)去
		applicationContext.refresh();
	}

public final void refresh() throws BeansException, IllegalStateException {
		try {
            //繼續(xù)跳轉(zhuǎn)到父類AbstractApplicationContext方法
			super.refresh();
		}
		catch (RuntimeException ex) {
			WebServer webServer = this.webServer;
			if (webServer != null) {
				webServer.stop();
			}
			throw ex;
		}
	}

//springboot 大部分的初始化工作是在這里完成的，不過這不是我們本地的重點(diǎn)，不相關(guān)的我們統(tǒng)統(tǒng)略過
public void refresh() throws BeansException, IllegalStateException {
		synchronized (this.startupShutdownMonitor) {
			......
			try {
			......
				//繼續(xù)點(diǎn)到這個(gè)方法，這里又會(huì)跳轉(zhuǎn)到ServletWebServerApplicationContext這個(gè)類的方法
				onRefresh();
			.....
			}

			catch (BeansException ex) {
			.....
			}

			finally {
			.....
			}
		}
	}

protected void onRefresh() {
		super.onRefresh();
		try {
			//這里就是我們本次的重點(diǎn)，會(huì)在這里創(chuàng)建具體的web容器，我們點(diǎn)進(jìn)去看看，還是ServletWebServerApplicationContext這個(gè)類的方法
			createWebServer();
		}
		catch (Throwable ex) {
			throw new ApplicationContextException("Unable to start web server", ex);
		}
	}

private void createWebServer() {
	
		WebServer webServer = this.webServer;
		ServletContext servletContext = getServletContext();
		//第一次進(jìn)來webServer servletContext都是null,會(huì)進(jìn)到if分支里面
		if (webServer  == null && servletContext == null) {
		   //這里只是做個(gè)標(biāo)記，不用關(guān)注，跳過
			StartupStep createWebServer = this.getApplicationStartup().start("spring.boot.webserver.create");
			//這里就會(huì)來查找ServletWebServerFactory，也就是web容器的工廠,具體看下getWebServerFactory()方法，還是ServletWebServerApplicationContext這個(gè)類的方法
			ServletWebServerFactory factory = getWebServerFactory();
			createWebServer.tag("factory", factory.getClass().toString());
			this.webServer = factory.getWebServer(getSelfInitializer());
			createWebServer.end();
			getBeanFactory().registerSingleton("webServerGracefulShutdown",
					new WebServerGracefulShutdownLifecycle(this.webServer));
			getBeanFactory().registerSingleton("webServerStartStop",
					new WebServerStartStopLifecycle(this, this.webServer));
		}
		else if (servletContext != null) {
			try {
				getSelfInitializer().onStartup(servletContext);
			}
			catch (ServletException ex) {
				throw new ApplicationContextException("Cannot initialize servlet context", ex);
			}
		}
		initPropertySources();
	}

protected ServletWebServerFactory getWebServerFactory() {
		// Use bean names so that we don't consider the hierarchy
		//從beanFactory中查找ServletWebServerFactory類型的bean的定義，返回對應(yīng)bean的名字
		String[] beanNames = getBeanFactory().getBeanNamesForType(ServletWebServerFactory.class);
		if (beanNames.length == 0) {
			throw new ApplicationContextException("Unable to start ServletWebServerApplicationContext due to missing "
					+ "ServletWebServerFactory bean.");
		}
		if (beanNames.length > 1) {
			throw new ApplicationContextException("Unable to start ServletWebServerApplicationContext due to multiple "
					+ "ServletWebServerFactory beans : " + StringUtils.arrayToCommaDelimitedString(beanNames));
		}
        //這里會(huì)從beanFactory中返回bean的名字為beanNames[0],類型為ServletWebServerFactory.class的bean對象，如果當(dāng)前bean還未創(chuàng)建，則此時(shí)就會(huì)創(chuàng)建bean對象并返回	
		return getBeanFactory().getBean(beanNames[0], ServletWebServerFactory.class);
	}

# Auto Configuration Import Filters
org.springframework.boot.autoconfigure.AutoConfigurationImportFilter=\
org.springframework.boot.autoconfigure.condition.OnBeanCondition,\
org.springframework.boot.autoconfigure.condition.OnClassCondition,\
org.springframework.boot.autoconfigure.condition.OnWebApplicationCondition

# Auto Configure
org.springframework.boot.autoconfigure.EnableAutoConfiguration=\
......
#下面這個(gè)會(huì)在創(chuàng)建servelt中使用，下部分我們再關(guān)注它
org.springframework.boot.autoconfigure.web.servlet.DispatcherServletAutoConfiguration,\
#下面這個(gè)就是我們需要用到的
org.springframework.boot.autoconfigure.web.servlet.ServletWebServerFactoryAutoConfiguration,\
......
org.springframework.boot.autoconfigure.web.servlet.WebMvcAutoConfiguration,\
......

ServletWebServerFactoryConfiguration.EmbeddedTomcat.class,
ServletWebServerFactoryConfiguration.EmbeddedJetty.class,
ServletWebServerFactoryConfiguration.EmbeddedUndertow.class

protected ServletWebServerFactory getWebServerFactory() {
		.......
        //所以這里的邏輯實(shí)際上會(huì)執(zhí)行ServletWebServerFactoryConfiguration.EmbeddedTomcat類的tomcatServletWebServerFactory方法，返回TomcatServletWebServerFactory對象,相關(guān)的屬性注入等等這里就不講述了            
		return getBeanFactory().getBean(beanNames[0], ServletWebServerFactory.class);
	}

# Auto Configuration Import Filters
org.springframework.boot.autoconfigure.AutoConfigurationImportFilter=\
org.springframework.boot.autoconfigure.condition.OnBeanCondition,\
org.springframework.boot.autoconfigure.condition.OnClassCondition,\
org.springframework.boot.autoconfigure.condition.OnWebApplicationCondition

# Auto Configure
org.springframework.boot.autoconfigure.EnableAutoConfiguration=\
......
#現(xiàn)在我們重點(diǎn)來看這個(gè)類
org.springframework.boot.autoconfigure.web.servlet.DispatcherServletAutoConfiguration,\
org.springframework.boot.autoconfigure.web.servlet.ServletWebServerFactoryAutoConfiguration,\
......
org.springframework.boot.autoconfigure.web.servlet.WebMvcAutoConfiguration,\
......

@AutoConfigureOrder(Ordered.HIGHEST_PRECEDENCE)
@Configuration(proxyBeanMethods = false)
//我們當(dāng)前只關(guān)注這ConditionalOnWebApplication、ConditionalOnClass注解
//ConditionalOnWebApplication是根據(jù)type來判斷指定類是否存在
//當(dāng)前的type是 Type.SERVLET，是來查找org.springframework.web.context.support.GenericWebApplicationContext類是否存在，這個(gè)類存在于spring-web中，所以這個(gè)條件是true
@ConditionalOnWebApplication(type = Type.SERVLET)
//這個(gè)注解上面說過了 ，就是查找指定的類是否存在，這個(gè)是查找DispatcherServlet.class是否存在，這里也會(huì)返回true
@ConditionalOnClass(DispatcherServlet.class)
//上面兩個(gè)條件都成立，就會(huì)執(zhí)行后續(xù)的操作，去遍歷內(nèi)部類和方法
@AutoConfigureAfter(ServletWebServerFactoryAutoConfiguration.class)
public class DispatcherServletAutoConfiguration {

	/**
	 * The bean name for a DispatcherServlet that will be mapped to the root URL "/".
	 */
	public static final String DEFAULT_DISPATCHER_SERVLET_BEAN_NAME = "dispatcherServlet";

	/**
	 * The bean name for a ServletRegistrationBean for the DispatcherServlet "/".
	 */
	public static final String DEFAULT_DISPATCHER_SERVLET_REGISTRATION_BEAN_NAME = "dispatcherServletRegistration";

	@Configuration(proxyBeanMethods = false)
    //這里還是個(gè)條件，通過實(shí)現(xiàn)Condition接口，通過matches方法來判斷
    //DefaultDispatcherServletCondition這個(gè)類就在當(dāng)前這個(gè)文件里，matches判斷的結(jié)果也是true
	@Conditional(DefaultDispatcherServletCondition.class)
    //ServletRegistration.class這個(gè)類存在于tomcat-embed-core里面，這個(gè)結(jié)果也是true
	@ConditionalOnClass(ServletRegistration.class)
    //上面兩個(gè)條件成立，就會(huì)執(zhí)行后續(xù)的操作，去遍歷內(nèi)部類和方法
	@EnableConfigurationProperties(WebMvcProperties.class)
	protected static class DispatcherServletConfiguration {

        //beanFactory會(huì)創(chuàng)建這個(gè)DispatcherServletbean的定義，bean的名字就是dispatcherServlet
		@Bean(name = DEFAULT_DISPATCHER_SERVLET_BEAN_NAME)
		public DispatcherServlet dispatcherServlet(WebMvcProperties webMvcProperties) {
			DispatcherServlet dispatcherServlet = new DispatcherServlet();
			dispatcherServlet.setDispatchOptionsRequest(webMvcProperties.isDispatchOptionsRequest());
			dispatcherServlet.setDispatchTraceRequest(webMvcProperties.isDispatchTraceRequest());
			dispatcherServlet.setThrowExceptionIfNoHandlerFound(webMvcProperties.isThrowExceptionIfNoHandlerFound());
			dispatcherServlet.setPublishEvents(webMvcProperties.isPublishRequestHandledEvents());
			dispatcherServlet.setEnableLoggingRequestDetails(webMvcProperties.isLogRequestDetails());
			return dispatcherServlet;
		}

		@Bean
		@ConditionalOnBean(MultipartResolver.class)
		@ConditionalOnMissingBean(name = DispatcherServlet.MULTIPART_RESOLVER_BEAN_NAME)
		public MultipartResolver multipartResolver(MultipartResolver resolver) {
			// Detect if the user has created a MultipartResolver but named it incorrectly
			return resolver;
		}

	}

	@Configuration(proxyBeanMethods = false)
    //和上面的一樣，不說了
	@Conditional(DispatcherServletRegistrationCondition.class)
    //和上面的一樣，不說了
	@ConditionalOnClass(ServletRegistration.class)
	@EnableConfigurationProperties(WebMvcProperties.class)
    //這里會(huì)要在查找DispatcherServletConfiguration.class，并執(zhí)行加載bean定義的流程，這就是上面的類了
	@Import(DispatcherServletConfiguration.class)
	protected static class DispatcherServletRegistrationConfiguration {

		@Bean(name = DEFAULT_DISPATCHER_SERVLET_REGISTRATION_BEAN_NAME)
        //ConditionalOnBean查找是否存在指定bean的定義，這個(gè)方法要注入?yún)?shù)，需要這個(gè)類，當(dāng)前這里就是上面的dispatcherServlet方法定義的，這里也是存在的
		@ConditionalOnBean(value = DispatcherServlet.class, name = DEFAULT_DISPATCHER_SERVLET_BEAN_NAME)
        //DispatcherServlet dispatcherServlet這個(gè)就是dispatcherServlet這個(gè)方法定義的bean，在創(chuàng)建DispatcherServletRegistrationBean這個(gè)bean的時(shí)候，就會(huì)去查找dispatcherServlet是否存在，如果不存在，先創(chuàng)建dispatcherServlet這個(gè)bean,再創(chuàng)建DispatcherServletRegistrationBean
		public DispatcherServletRegistrationBean dispatcherServletRegistration(DispatcherServlet dispatcherServlet,
				WebMvcProperties webMvcProperties, ObjectProvider<MultipartConfigElement> multipartConfig) {
			DispatcherServletRegistrationBean registration = new DispatcherServletRegistrationBean(dispatcherServlet,
					webMvcProperties.getServlet().getPath());
			registration.setName(DEFAULT_DISPATCHER_SERVLET_BEAN_NAME);
			registration.setLoadOnStartup(webMvcProperties.getServlet().getLoadOnStartup());
			multipartConfig.ifAvailable(registration::setMultipartConfig);
			return registration;
		}

	}
  ......
}

private void createWebServer() {
		WebServer webServer = this.webServer;
		ServletContext servletContext = getServletContext();
		if (webServer == null && servletContext == null) {
			StartupStep createWebServer = this.getApplicationStartup().start("spring.boot.webserver.create");
			//上面我們已經(jīng)看到了這里，factory是TomcatServletWebServerFactory類的一個(gè)實(shí)例對象
			ServletWebServerFactory factory = getWebServerFactory();
            //這里還是做個(gè)標(biāo)記，不用關(guān)注
            createWebServer.tag("factory", factory.getClass().toString());
            //這里就是具體創(chuàng)建tomcat了，這里的入?yún)etSelfInitializer()是個(gè)lambda表達(dá)式，這個(gè)后續(xù)很重要
			this.webServer = factory.getWebServer(getSelfInitializer());
			createWebServer.end();
			getBeanFactory().registerSingleton("webServerGracefulShutdown",
					new WebServerGracefulShutdownLifecycle(this.webServer));
			getBeanFactory().registerSingleton("webServerStartStop",
					new WebServerStartStopLifecycle(this, this.webServer));
		}
		else if (servletContext != null) {
			try {
				getSelfInitializer().onStartup(servletContext);
			}
			catch (ServletException ex) {
				throw new ApplicationContextException("Cannot initialize servlet context", ex);
			}
		}
		initPropertySources();
	}

private org.springframework.boot.web.servlet.ServletContextInitializer getSelfInitializer() {
		return this::selfInitialize;
	}
	//是創(chuàng)建webServer的參數(shù)
	private void selfInitialize(ServletContext servletContext) throws ServletException {
		prepareWebApplicationContext(servletContext);
		registerApplicationScope(servletContext);
		WebApplicationContextUtils.registerEnvironmentBeans(getBeanFactory(), servletContext);
		for (ServletContextInitializer beans : getServletContextInitializerBeans()) {
			beans.onStartup(servletContext);
		}
	}

public WebServer getWebServer(ServletContextInitializer... initializers) {
        .......
		//上面的入?yún)?huì)在這里傳下去
		prepareContext(tomcat.getHost(), initializers);
		return getTomcatWebServer(tomcat);
	}

protected void prepareContext(Host host, ServletContextInitializer[] initializers) {
		......
		ServletContextInitializer[] initializersToUse = mergeInitializers(initializers);
		host.addChild(context);
		//繼續(xù)傳下去
		configureContext(context, initializersToUse);
		postProcessContext(context);
	}

protected void configureContext(Context context, ServletContextInitializer[] initializers) {
		//會(huì)傳遞給TomcatStarter，作為構(gòu)造參數(shù)，下面我們?nèi)ミ@里看看
		TomcatStarter starter = new TomcatStarter(initializers);
        ......
    }

這個(gè)類不長
class TomcatStarter implements ServletContainerInitializer {
    ......
	TomcatStarter(ServletContextInitializer[] initializers) {
        //入?yún)?huì)作為它的成員屬性
		this.initializers = initializers;
	}

	@Override
	public void onStartup(Set<Class<?>> classes, ServletContext servletContext) throws ServletException {
		try {
			for (ServletContextInitializer initializer : this.initializers) {
                //會(huì)在這里調(diào)用onStartup方法，這里的入?yún)⒕褪茿pplicationContextFacade的對象，里面包裝了ApplicationContext，里面再包裝了TomcatEmbeddedContext，這要就和tomcat聯(lián)系起來了，下面的截圖就是servletContext的對象結(jié)構(gòu)
				initializer.onStartup(servletContext);
			}
		}
		catch (Exception ex) {
			......
	}

private void selfInitialize(ServletContext servletContext) throws ServletException {
        //這里是將ApplicationContextFacade設(shè)置到當(dāng)前的servletContext上
		prepareWebApplicationContext(servletContext);
        //這里是在beanFactory中注冊application的scope
		registerApplicationScope(servletContext);
        //這里還是注冊上下文相關(guān)的bean
		WebApplicationContextUtils.registerEnvironmentBeans(getBeanFactory(), servletContext);
        //我們重點(diǎn)來看這里getServletContextInitializerBeans()是定義個(gè)一個(gè)ServletContextInitializerBeans對象，我們點(diǎn)進(jìn)去看看
		for (ServletContextInitializer beans : getServletContextInitializerBeans()) {
			beans.onStartup(servletContext);
		}
	}

protected Collection<ServletContextInitializer> getServletContextInitializerBeans() {
		//這里的getBeanFactory()就是全局的beanFactory
		return new ServletContextInitializerBeans(getBeanFactory());
	}

public ServletContextInitializerBeans(ListableBeanFactory beanFactory,
			Class<? extends ServletContextInitializer>... initializerTypes) {
		this.initializers = new LinkedMultiValueMap<>();
        //由于我們沒有傳initializerTypes這個(gè)參數(shù)，所以this.initializerTypes里面就只有ServletContextInitializer.class這個(gè)類
		this.initializerTypes = (initializerTypes.length != 0) ? Arrays.asList(initializerTypes)
				: Collections.singletonList(ServletContextInitializer.class);
        //這里主要是從beanFactory中查找this.initializerTypes類型，我們進(jìn)去看看，就是下面這個(gè)方法了
		addServletContextInitializerBeans(beanFactory);
		addAdaptableBeans(beanFactory);
		List<ServletContextInitializer> sortedInitializers = this.initializers.values().stream()
				.flatMap((value) -> value.stream().sorted(AnnotationAwareOrderComparator.INSTANCE))
				.collect(Collectors.toList());
		this.sortedList = Collections.unmodifiableList(sortedInitializers);
		logMappings(this.initializers);
	}

	private void addServletContextInitializerBeans(ListableBeanFactory beanFactory) {
		for (Class<? extends ServletContextInitializer> initializerType : this.initializerTypes) {
            //默認(rèn)情況下這里找到就只有上面第3部分的DispatcherServletRegistrationBean對應(yīng)的bean
			for (Entry<String, ? extends ServletContextInitializer> initializerBean : getOrderedBeansOfType(beanFactory,
					initializerType)) {
                //這里的key是bean的名字,value就是bean對象，在進(jìn)去看看，就是下面這個(gè)方法
				addServletContextInitializerBean(initializerBean.getKey(), initializerBean.getValue(), beanFactory);
			}
		}
	}
	private void addServletContextInitializerBean(String beanName, ServletContextInitializer initializer,
			ListableBeanFactory beanFactory) {
        //會(huì)走到這個(gè)分支
		if (initializer instanceof ServletRegistrationBean) {
            //這里返回的servlet也還是第3部分DispatcherServlet對應(yīng)的bean
			Servlet source = ((ServletRegistrationBean<?>) initializer).getServlet();
            //再點(diǎn)進(jìn)去
			addServletContextInitializerBean(Servlet.class, beanName, initializer, beanFactory, source);
		}
		else if (initializer instanceof FilterRegistrationBean) {
			Filter source = ((FilterRegistrationBean<?>) initializer).getFilter();
			addServletContextInitializerBean(Filter.class, beanName, initializer, beanFactory, source);
		}
		else if (initializer instanceof DelegatingFilterProxyRegistrationBean) {
			String source = ((DelegatingFilterProxyRegistrationBean) initializer).getTargetBeanName();
			addServletContextInitializerBean(Filter.class, beanName, initializer, beanFactory, source);
		}
		else if (initializer instanceof ServletListenerRegistrationBean) {
			EventListener source = ((ServletListenerRegistrationBean<?>) initializer).getListener();
			addServletContextInitializerBean(EventListener.class, beanName, initializer, beanFactory, source);
		}
		else {
			addServletContextInitializerBean(ServletContextInitializer.class, beanName, initializer, beanFactory,
					initializer);
		}
	}

	private void addServletContextInitializerBean(Class<?> type, String beanName, ServletContextInitializer initializer,
			ListableBeanFactory beanFactory, Object source) {
        //這里的initializers是個(gè)map,按照類型，bean對象進(jìn)行加載，這里的type是javax.servlet.Servlet.class,value是上面的DispatcherServletRegistrationBean
		this.initializers.add(type, initializer);
		if (source != null) {
			// Mark the underlying source as seen in case it wraps an existing bean
            //將DispatcherServlet對應(yīng)的bean加到這里
			this.seen.add(source);
		}
		if (logger.isTraceEnabled()) {
			String resourceDescription = getResourceDescription(beanName, beanFactory);
			int order = getOrder(initializer);
			logger.trace("Added existing " + type.getSimpleName() + " initializer bean '" + beanName + "'; order="
					+ order + ", resource=" + resourceDescription);
		}
	}

public ServletContextInitializerBeans(ListableBeanFactory beanFactory,
			Class<? extends ServletContextInitializer>... initializerTypes) {
		...... //這里的內(nèi)容上面已經(jīng)看過了，我們現(xiàn)在看下面這句，點(diǎn)進(jìn)去
		addAdaptableBeans(beanFactory);
		List<ServletContextInitializer> sortedInitializers = this.initializers.values().stream()
				.flatMap((value) -> value.stream().sorted(AnnotationAwareOrderComparator.INSTANCE))
				.collect(Collectors.toList());
		this.sortedList = Collections.unmodifiableList(sortedInitializers);
		logMappings(this.initializers);
	}

protected void addAdaptableBeans(ListableBeanFactory beanFactory) {
		//這句不用關(guān)注
		MultipartConfigElement multipartConfig = getMultipartConfig(beanFactory);
		//這句不用關(guān)注
		addAsRegistrationBean(beanFactory, Servlet.class, new ServletRegistrationBeanAdapter(multipartConfig));
		//點(diǎn)到這里去看看
		addAsRegistrationBean(beanFactory, Filter.class, new FilterRegistrationBeanAdapter());
        
		for (Class<?> listenerType : ServletListenerRegistrationBean.getSupportedTypes()) {
			addAsRegistrationBean(beanFactory, EventListener.class, (Class<EventListener>) listenerType,
					new ServletListenerRegistrationBeanAdapter());
		}
	}

private <T, B extends T> void addAsRegistrationBean(ListableBeanFactory beanFactory, Class<T> type,
			Class<B> beanType, RegistrationBeanAdapter<T> adapter) {
		//這里的beanType是 Filter.class,下面這句就是從beanFactory中獲取所有類型為Filter.class的bean
		List<Map.Entry<String, B>> entries = getOrderedBeansOfType(beanFactory, beanType, this.seen);
		for (Entry<String, B> entry : entries) {
			String beanName = entry.getKey();
			B bean = entry.getValue();
            //將bean放置到this.seen里面
			if (this.seen.add(bean)) {
				// One that we haven't already seen
                //包裝成RegistrationBean對象
				RegistrationBean registration = adapter.createRegistrationBean(beanName, bean, entries.size());
				int order = getOrder(bean);
				registration.setOrder(order);
                //同樣放置到this.initializers里面
				this.initializers.add(type, registration);
				if (logger.isTraceEnabled()) {
					logger.trace("Created " + type.getSimpleName() + " initializer for bean '" + beanName + "'; order="
							+ order + ", resource=" + getResourceDescription(beanName, beanFactory));
				}
			}
		}
	}

protected void addAdaptableBeans(ListableBeanFactory beanFactory) {
		......//這里剛才說過了
         //下面這部分不說了，這里基本和上面一樣，不過處理的類型變成了ServletContextAttributeListener.class、ServletRequestListener.class、ServletRequestAttributeListener.class、HttpSessionAttributeListener.class、HttpSessionIdListener.class、HttpSessionListener.class、ServletContextListener.class這些類型
		for (Class<?> listenerType : ServletListenerRegistrationBean.getSupportedTypes()) {
			addAsRegistrationBean(beanFactory, EventListener.class, (Class<EventListener>) listenerType,
					new ServletListenerRegistrationBeanAdapter());
		}
	}

public ServletContextInitializerBeans(ListableBeanFactory beanFactory,
			Class<? extends ServletContextInitializer>... initializerTypes) {
		......//這里剛才都說過了，看下面
        //這里就是把上面所有獲取到的相關(guān)的bean放置到this.sortedList中，下面我是我本地this.sortedList的截圖
		List<ServletContextInitializer> sortedInitializers = this.initializers.values().stream()
				.flatMap((value) -> value.stream().sorted(AnnotationAwareOrderComparator.INSTANCE))
				.collect(Collectors.toList());
		this.sortedList = Collections.unmodifiableList(sortedInitializers);
		logMappings(this.initializers);
	}

public class ServletContextInitializerBeans extends AbstractCollection<ServletContextInitializer>

public abstract Iterator<E> iterator();

@Override
public Iterator<ServletContextInitializer> iterator() {
   return this.sortedList.iterator();
}

private void selfInitialize(ServletContext servletContext) throws ServletException {
	......//這里上面都說過了
	//getServletContextInitializerBeans()這個(gè)方法就是構(gòu)造了ServletContextInitializerBeans
	//這里的for循環(huán)也是調(diào)用了ServletContextInitializerBeans的iterator的方法，實(shí)際上遍歷的也就是上面的this.sortedList
	for (ServletContextInitializer beans : getServletContextInitializerBeans()) {
		//這里就是把在beanFactory中查找到的Servlet.class,filter.class，監(jiān)聽器等等添加到tomcat容器中,我們就只進(jìn)到servlet里面去看看
		//進(jìn)到DispatcherServletRegistrationBean里面去看看
		beans.onStartup(servletContext);
	}
}

//這個(gè)方法在DispatcherServletRegistrationBean的父類RegistrationBean中
	//所有的Servlet.class,filter.class，監(jiān)聽器都會(huì)走到這里
	public final void onStartup(ServletContext servletContext) throws ServletException {
		//這里是返回的表述，不關(guān)注
		String description = getDescription();
		if (!isEnabled()) {
			logger.info(StringUtils.capitalize(description) + " was not registered (disabled)");
			return;
		}
		//這里由不同的子類去實(shí)現(xiàn)，DispatcherServletRegistrationBean會(huì)調(diào)用到ServletRegistrationBean中
		register(description, servletContext);
	}

//這個(gè)方法是在ServletRegistrationBean這個(gè)類中
	@Override
	protected ServletRegistration.Dynamic addRegistration(String description, ServletContext servletContext) {
		String name = getServletName();
		//這里的servletContext上面的ApplicationContextFacade的對象，這里就會(huì)將DispatcherServlet的bean對象加載到TomcatEmbeddedContext中，后續(xù)所有的http請求最后都會(huì)流轉(zhuǎn)到DispatcherServlet去進(jìn)行具體的分發(fā)
		return servletContext.addServlet(name, this.servlet);
	}

# Auto Configuration Import Filters
org.springframework.boot.autoconfigure.AutoConfigurationImportFilter=\
org.springframework.boot.autoconfigure.condition.OnBeanCondition,\
org.springframework.boot.autoconfigure.condition.OnClassCondition,\
org.springframework.boot.autoconfigure.condition.OnWebApplicationCondition

# Auto Configure
org.springframework.boot.autoconfigure.EnableAutoConfiguration=\
......
org.springframework.boot.autoconfigure.web.servlet.DispatcherServletAutoConfiguration,\
org.springframework.boot.autoconfigure.web.servlet.ServletWebServerFactoryAutoConfiguration,\
......
#現(xiàn)在我們重點(diǎn)來看這個(gè)類
org.springframework.boot.autoconfigure.web.servlet.WebMvcAutoConfiguration,\
......

//這里會(huì)創(chuàng)建RequestMappingHandlerMapping的bean
		@Bean
		@Primary
		@Override
		public RequestMappingHandlerMapping requestMappingHandlerMapping(
				@Qualifier("mvcContentNegotiationManager") ContentNegotiationManager contentNegotiationManager,
				@Qualifier("mvcConversionService") FormattingConversionService conversionService,
				@Qualifier("mvcResourceUrlProvider") ResourceUrlProvider resourceUrlProvider) {
			// Must be @Primary for MvcUriComponentsBuilder to work
			return super.requestMappingHandlerMapping(contentNegotiationManager, conversionService,
					resourceUrlProvider);

@Override
	public void afterPropertiesSet() {
		initHandlerMethods();
	}

	/**
	 * Scan beans in the ApplicationContext, detect and register handler methods.
	 * @see #getCandidateBeanNames()
	 * @see #processCandidateBean
	 * @see #handlerMethodsInitialized
	 */
	protected void initHandlerMethods() {
        //這里查找beanFactory中的所有bean進(jìn)行遍歷
		for (String beanName : getCandidateBeanNames()) {
			if (!beanName.startsWith(SCOPED_TARGET_NAME_PREFIX)) {
                //點(diǎn)到這里去看看
				processCandidateBean(beanName);
			}
		}
		handlerMethodsInitialized(getHandlerMethods());
	}

protected void processCandidateBean(String beanName) {
		Class<?> beanType = null;
		try {
			//根據(jù)beanName獲取對應(yīng)bean的Class對象
			beanType = obtainApplicationContext().getType(beanName);
		}
		catch (Throwable ex) {
			// An unresolvable bean type, probably from a lazy bean - let's ignore it.
			if (logger.isTraceEnabled()) {
				logger.trace("Could not resolve type for bean '" + beanName + "'", ex);
			}
		}
		//判斷類上是否有Controller.class，RequestMapping.class注解
		if (beanType != null && isHandler(beanType)) {
			//這里就會(huì)解析beanName上的所有方法進(jìn)行遍歷，查找有 RequestMapping.class注解的方法，創(chuàng)建RequestMappingInfo對象，放置到registry屬性中(在AbstractHandlerMethodMapping)中，這樣我們所有定義的controller中的http請求就會(huì)全部被掃描到
			detectHandlerMethods(beanName);
		}
	}

protected void initStrategies(ApplicationContext context) {
		......
		這就會(huì)加載之前查找到的RequestMappingHandlerMapping中的我們定義的controller
		initHandlerMappings(context);
		......
	}

private void initHandlerMappings(ApplicationContext context) {
		this.handlerMappings = null;

		if (this.detectAllHandlerMappings) {
			// Find all HandlerMappings in the ApplicationContext, including ancestor contexts.
			//這里會(huì)在beanFactory中查找所有HandlerMapping.class的bean,其中就包含我們第5部分的RequestMappingHandlerMapping
			Map<String, HandlerMapping> matchingBeans =
					BeanFactoryUtils.beansOfTypeIncludingAncestors(context, HandlerMapping.class, true, false);
			if (!matchingBeans.isEmpty()) {
			//將所有查找到的放置到handlerMappings中
				this.handlerMappings = new ArrayList<>(matchingBeans.values());
				// We keep HandlerMappings in sorted order.
				AnnotationAwareOrderComparator.sort(this.handlerMappings);
			}
		}
		......
	}

protected void doDispatch(HttpServletRequest request, HttpServletResponse response) throws Exception {
		......

		try {
			ModelAndView mv = null;
			Exception dispatchException = null;

			try {
				processedRequest = checkMultipart(request);
				multipartRequestParsed = (processedRequest != request);

				// Determine handler for the current request.
                //在這里，就會(huì)請求request的請求路徑去查找實(shí)際要執(zhí)行的controller的方法，點(diǎn)進(jìn)去看看
				mappedHandler = getHandler(processedRequest);
				......
	}

@Nullable
	protected HandlerExecutionChain getHandler(HttpServletRequest request) throws Exception {
		if (this.handlerMappings != null) {
            //這其實(shí)就是根據(jù)遍歷，查找對應(yīng)的路徑，這個(gè)this.handlerMappings就是就是在initHandlerMappings方法中賦值的
			for (HandlerMapping mapping : this.handlerMappings) {
				HandlerExecutionChain handler = mapping.getHandler(request);
				if (handler != null) {
					return handler;
				}
			}
		}
		return null;
	}