Spring 4.x IOC介绍（五.Spring boot 启动流程以及 IoC 构建）

男娘i 2021-11-22 07:16 368阅读 0赞

> ***基于Spring boot - 2.0.1.RELEAS***

之前的文章介绍了：BeanFactory 、ApplicationContext、WebApplicationContext  
也写了各个部分的实现，总觉得缺点什么，最近整理自己博客的时候，终于发现了。少SpringBoot的啊。  
[Spring 4.x IOC介绍（一.BeanFactory 、ApplicationContext、WebApplicationContext之BeanFactory）][Spring 4.x IOC_.BeanFactory _ApplicationContext_WebApplicationContext_BeanFactory]

[Spring 4.x IOC介绍（二.BeanFactory 、ApplicationContext、WebApplicationContext之ApplicationContext）  
][Spring 4.x IOC_.BeanFactory _ApplicationContext_WebApplicationContext_ApplicationContext_]

[Spring 4.x IOC介绍（三.BeanFactory 、ApplicationContext、WebApplicationContext之WebApplicationContext）  
][Spring 4.x IOC_.BeanFactory _ApplicationContext_WebApplicationContext_WebApplicationContext_]

[Spring 4.x IOC介绍（四.BeanFactory 、ApplicationContext、WebApplicationContext——总结）][Spring 4.x IOC_.BeanFactory _ApplicationContext_WebApplicationContext]

但是现在使用Spring Boot居多，在启动SpringBoot的时候，是如何创建Bean的？这篇文章说一下SpringBoot启动以及创建Bean。

# Spring boot 启动代码 #

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

两个重点

*  @SpringBootApplication 注解
 *  SpringApplication.run() 方法。

一个一个看

# @SpringBootApplication 源码 #

@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 {
    
    	/**
    	 * Exclude specific auto-configuration classes such that they will never be applied.
    	 * @return the classes to exclude
    	 */
    	@AliasFor(annotation = EnableAutoConfiguration.class)
    	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
    	 */
    	@AliasFor(annotation = EnableAutoConfiguration.class)
    	String[] excludeName() default {};
    
    	/**
    	 * Base packages to scan for annotated components. Use {@link #scanBasePackageClasses}
    	 * for a type-safe alternative to String-based package names.
    	 * @return base packages to scan
    	 * @since 1.3.0
    	 */
    	@AliasFor(annotation = ComponentScan.class, attribute = "basePackages")
    	String[] scanBasePackages() default {};
    
    	/**
    	 * Type-safe alternative to {@link #scanBasePackages} for specifying the packages to
    	 * scan for annotated components. The package of each class specified will be scanned.
    	 * <p>
    	 * Consider creating a special no-op marker class or interface in each package that
    	 * serves no purpose other than being referenced by this attribute.
    	 * @return base packages to scan
    	 * @since 1.3.0
    	 */
    	@AliasFor(annotation = ComponentScan.class, attribute = "basePackageClasses")
    	Class<?>[] scanBasePackageClasses() default {};
    
    }

## SpringBootApplication 注解 ##

比较重要的几个注解：

### @SpringBootConfiguration ###

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

@SpringBootConfiguration继承自@Configuration，二者功能也一致(可以穿插使用)，标注当前类是配置类，  
并会将当前类内声明的一个或多个以@Bean注解标记的方法的实例纳入到spring容器中，并且实例名就是方法名。

### @EnableAutoConfiguration ###

@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 {};
    
    }

借助@Import的帮助，将所有符合自动配置条件的bean定义加载到IoC容器（建议放在根包路径下，这样可以扫描子包和类）。

可以看到`@Import(AutoConfigurationImportSelector.class)`  
看下 AutoConfigurationImportSelector.Class

#### AutoConfigurationImportSelector ####

看下类继承关系：  
![AutoConfigurationImportSelector][]  
`AutoConfigurationImportSelector`最终实现了`ImportSelector#selectImports`，代码如下

@Override
    	public String[] selectImports(AnnotationMetadata annotationMetadata) {
    		if (!isEnabled(annotationMetadata)) {
    			return NO_IMPORTS;
    		}
    		// 1.从META-INF/spring-autoconfigure-metadata.properties文件中载入配置属性
    		AutoConfigurationMetadata autoConfigurationMetadata = AutoConfigurationMetadataLoader
    				.loadMetadata(this.beanClassLoader);
    		//2.获取注解属性
    		AnnotationAttributes attributes = getAttributes(annotationMetadata);
    		// 3.获取配置信息
    		List<String> configurations = getCandidateConfigurations(annotationMetadata,
    				attributes);
    		// //4.移除重复的
    		configurations = removeDuplicates(configurations);
    		// 6.获取需要排除的
    		Set<String> exclusions = getExclusions(annotationMetadata, attributes);
    		// 7.校验排除类
    		checkExcludedClasses(configurations, exclusions);
    		// 8.删除所有需要排除的
    		configurations.removeAll(exclusions);
    		// 9.过滤器OnClassCondition（注解中配置的当存在某类才生效）
    		configurations = filter(configurations, autoConfigurationMetadata);
    		// 10.触发自动配置导入监听事件
    		fireAutoConfigurationImportEvents(configurations, exclusions);
    		return StringUtils.toStringArray(configurations);
    	}

### @ComponentScan ###

@Retention(RetentionPolicy.RUNTIME)
    @Target(ElementType.TYPE)
    @Documented
    @Repeatable(ComponentScans.class)
    public @interface ComponentScan {
    
    	@AliasFor("basePackages")
    	String[] value() default {};
    
    	@AliasFor("value")
    	String[] basePackages() default {};
    
    	Class<?>[] basePackageClasses() default {};
    
    	Class<? extends BeanNameGenerator> nameGenerator() default BeanNameGenerator.class;
    
    	Class<? extends ScopeMetadataResolver> scopeResolver() default AnnotationScopeMetadataResolver.class;
    
    	ScopedProxyMode scopedProxy() default ScopedProxyMode.DEFAULT;
    
    	String resourcePattern() default ClassPathScanningCandidateComponentProvider.DEFAULT_RESOURCE_PATTERN;
    	
    	boolean useDefaultFilters() default true;
    
    	Filter[] includeFilters() default {};
    
    	Filter[] excludeFilters() default {};
    
    	boolean lazyInit() default false;
    
    	@Retention(RetentionPolicy.RUNTIME)
    	@Target({})
    	@interface Filter {
    
    		FilterType type() default FilterType.ANNOTATION;
    		
    		@AliasFor("classes")
    		Class<?>[] value() default {};
    		
    		@AliasFor("value")
    		Class<?>[] classes() default {};
    		
    		String[] pattern() default {};
    
    	}
    
    }

spring的自动扫描并加载符合条件的组件，可定义扫描范围，加载到IOC容器

我们可以通过basePackages等属性来细粒度的定制@ComponentScan自动扫描的范围，如果不指定，则默认Spring框架实现会从声明@ComponentScan所在类的package进行扫描。

# SpringApplication.run() 方法 #

public static ConfigurableApplicationContext run(Class<?> primarySource,
    			String... args) {
    		return run(new Class<?>[] { primarySource }, args);
    	}
    
    	public static ConfigurableApplicationContext run(Class<?>[] primarySources,
    			String[] args) {
    		// 创建SpringApplication对象，并调用run方法。
    		return new SpringApplication(primarySources).run(args);
    	}

## new SpringApplication(primarySources).——创建SpringApplication实例 ##

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 = deduceWebApplicationType();
    		setInitializers((Collection) getSpringFactoriesInstances(
    				ApplicationContextInitializer.class));
    		setListeners((Collection) getSpringFactoriesInstances(ApplicationListener.class));
    		this.mainApplicationClass = deduceMainApplicationClass();
    	}
    
    	private WebApplicationType deduceWebApplicationType() {
    		if (ClassUtils.isPresent(REACTIVE_WEB_ENVIRONMENT_CLASS, null)
    				&& !ClassUtils.isPresent(MVC_WEB_ENVIRONMENT_CLASS, null)) {
    			return WebApplicationType.REACTIVE;
    		}
    		for (String className : WEB_ENVIRONMENT_CLASSES) {
    			if (!ClassUtils.isPresent(className, null)) {
    				return WebApplicationType.NONE;
    			}
    		}
    		return WebApplicationType.SERVLET;
    	}

判断了webApplicationType是不是SERVLET，如果是，则创建Servlet的环境，否则创建基本环境。  
spring boot是通过检查当前环境中是否存在  
`org.springframework.web.servlet.DispatcherServlet`类来判断当前是否是web环境的。  
接着往下看，获得了`ConfigurableEnvironment`环境以后，通过后面的代码对环境进行“微调”。  
通过`configureIgnoreBeanInfo(environment)`;如果`System`中的`spring.beaninfo.ignore`属性为空，就把当前环境中的属性覆盖上去：

## run(String\[\] args) 核心方法。 ##

public ConfigurableApplicationContext run(String... args) {
    		// 创建秒表
    		StopWatch stopWatch = new StopWatch();
    		// 开始计时
    		stopWatch.start();
    		ConfigurableApplicationContext context = null;
    		Collection<SpringBootExceptionReporter> exceptionReporters = new ArrayList<>();
    		configureHeadlessProperty();
    		// 1.获取监听器
    		SpringApplicationRunListeners listeners = getRunListeners(args);
    		// 2.启动
    		listeners.starting();
    		try {
    			// 3.获取ApplicationArguments对象
    			ApplicationArguments applicationArguments = new DefaultApplicationArguments(
    					args);
    			// 4.准备环境，并触发 ApplicationEnvironmentPreparedEvent 事件
    			ConfigurableEnvironment environment = prepareEnvironment(listeners,
    					applicationArguments);
    			// 4.1.如果System中的spring.beaninfo.ignore属性为空，就把当前环境中的属性覆盖上去：
    			configureIgnoreBeanInfo(environment);
    			
    			Banner printedBanner = printBanner(environment);
    			// 5.创建应用上下文
    			context = createApplicationContext();
    			exceptionReporters = getSpringFactoriesInstances(
    					SpringBootExceptionReporter.class,
    					new Class[] { ConfigurableApplicationContext.class }, context);
    			// 5.1.准备上下文
    			prepareContext(context, environment, listeners, applicationArguments,
    					printedBanner);
    			// 5.2刷新上下文
    			refreshContext(context);
    			// 5.3刷新上下文后
    			afterRefresh(context, applicationArguments);
    			// 结束计时
    			stopWatch.stop();
    			if (this.logStartupInfo) {
    				new StartupInfoLogger(this.mainApplicationClass)
    						.logStarted(getApplicationLog(), stopWatch);
    			}
    			listeners.started(context);
    			callRunners(context, applicationArguments);
    		}
    		catch (Throwable ex) {
    			handleRunFailure(context, ex, exceptionReporters, listeners);
    			throw new IllegalStateException(ex);
    		}
    
    		try {
    			listeners.running(context);
    		}
    		catch (Throwable ex) {
    			handleRunFailure(context, ex, exceptionReporters, null);
    			throw new IllegalStateException(ex);
    		}
    		return context;
    	}

### SpringApplicationRunListeners listeners = getRunListeners(args); —— 获取监听器 ###

private SpringApplicationRunListeners getRunListeners(String[] args) {
    		Class<?>[] types = new Class<?>[] { SpringApplication.class, String[].class };
    		return new SpringApplicationRunListeners(logger, getSpringFactoriesInstances(
    				SpringApplicationRunListener.class, types, this, args));
    	}
    	
    	SpringApplicationRunListeners(Log log,
    			Collection<? extends SpringApplicationRunListener> listeners) {
    		this.log = log;
    		this.listeners = new ArrayList<>(listeners);
    	}
    	
    	private <T> Collection<T> getSpringFactoriesInstances(Class<T> type,
    			Class<?>[] parameterTypes, Object... args) {
    		ClassLoader classLoader = Thread.currentThread().getContextClassLoader();
    		// Use names and ensure unique to protect against duplicates
    		// 使用名称并确保唯一以防止重复—加载工厂名字
    		Set<String> names = new LinkedHashSet<>(
    				SpringFactoriesLoader.loadFactoryNames(type, classLoader));
    		// 创建 工厂实例
    		List<T> instances = createSpringFactoriesInstances(type, parameterTypes,
    				classLoader, args, names);
    		// 排序
    		AnnotationAwareOrderComparator.sort(instances);
    		return instances;
    	}
    
    	// 加载工厂名
    	public static List<String> loadFactoryNames(Class<?> factoryClass, @Nullable ClassLoader classLoader) {
    		String factoryClassName = factoryClass.getName();
    		return loadSpringFactories(classLoader).getOrDefault(factoryClassName, Collections.emptyList());
    	}
    	
    	// 加载工厂
    	private static Map<String, List<String>> loadSpringFactories(@Nullable ClassLoader classLoader) {
    		MultiValueMap<String, String> result = cache.get(classLoader);
    		if (result != null) {
    			return result;
    		}
    
    		try {
    			// 路径：FACTORIES_RESOURCE_LOCATION = META-INF/spring.factories
    			Enumeration<URL> urls = (classLoader != null ?
    					classLoader.getResources(FACTORIES_RESOURCE_LOCATION) :
    					ClassLoader.getSystemResources(FACTORIES_RESOURCE_LOCATION));
    			result = new LinkedMultiValueMap<>();
    			while (urls.hasMoreElements()) {
    				URL url = urls.nextElement();
    				UrlResource resource = new UrlResource(url);
    				// 加载属性
    				Properties properties = PropertiesLoaderUtils.loadProperties(resource);
    				for (Map.Entry<?, ?> entry : properties.entrySet()) {
    					List<String> factoryClassNames = Arrays.asList(
    							StringUtils.commaDelimitedListToStringArray((String) entry.getValue()));
    					result.addAll((String) entry.getKey(), factoryClassNames);
    				}
    			}
    			cache.put(classLoader, result);
    			return result;
    		}
    		catch (IOException ex) {
    			throw new IllegalArgumentException("Unable to load factories from location [" +
    					FACTORIES_RESOURCE_LOCATION + "]", ex);
    		}
    	}
    
    	public static Properties loadProperties(Resource resource) throws IOException {
    		Properties props = new Properties();
    		// 填充属性
    		fillProperties(props, resource);
    		return props;
    	}
    
    	// 从给定的资源中填充给定的属性（采用ISO-8859-1编码）
    	public static void fillProperties(Properties props, Resource resource) throws IOException {
    		InputStream is = resource.getInputStream();
    		try {
    			String filename = resource.getFilename();
    			if (filename != null && filename.endsWith(XML_FILE_EXTENSION)) {
    				props.loadFromXML(is);
    			}
    			else {
    				props.load(is);
    			}
    		}
    		finally {
    			is.close();
    		}
    	}

### ConfigurableEnvironment environment = prepareEnvironment(listeners, applicationArguments); — 准备环境 ###

private ConfigurableEnvironment prepareEnvironment(
    			SpringApplicationRunListeners listeners,
    			ApplicationArguments applicationArguments) {
    		// Create and configure the environment
    		// 得到环境对象ConfigurableEnvironment，没有则创建一个StandardServletEnvironment
    		// 
    		ConfigurableEnvironment environment = getOrCreateEnvironment();
    		// 配置环境信息（激活环境，通过从系统环境变量里取）
    		configureEnvironment(environment, applicationArguments.getSourceArgs());
    		// 发布ApplicationEnvironmentPreparedEvent事件，加载配置文件，具体请看（ConfigFileApplicationListener）。
    		listeners.environmentPrepared(environment);
    		bindToSpringApplication(environment);
    		if (this.webApplicationType == WebApplicationType.NONE) {
    			environment = new EnvironmentConverter(getClassLoader())
    					.convertToStandardEnvironmentIfNecessary(environment);
    		}
    		ConfigurationPropertySources.attach(environment);
    		return environment;
    	}
    
    	protected void configureEnvironment(ConfigurableEnvironment environment,String[] args) {
    		configurePropertySources(environment, args);
    		// 配置ConfigurableEnvironment中的激活属性
    		configureProfiles(environment, args);
    	}
    	protected void configureProfiles(ConfigurableEnvironment environment, String[] args) {
    		environment.getActiveProfiles(); // ensure they are initialized
    		// additionalProfiles是项目启动时在main中SpringApplication.setAdditionalProfiles("")配置的
    		Set<String> profiles = new LinkedHashSet<>(this.additionalProfiles);
    		// 获取环境变量中设置的spring.profiles.active属性
    		profiles.addAll(Arrays.asList(environment.getActiveProfiles()));
    		// 赋值 activeProfiles
    		environment.setActiveProfiles(StringUtils.toStringArray(profiles));
    	}

### createApplicationContext() —— 创建应用上下文 ###

protected ConfigurableApplicationContext createApplicationContext() {
    		Class<?> contextClass = this.applicationContextClass;
    		if (contextClass == null) {
    			try {
    				switch (this.webApplicationType) {
    				case SERVLET:
    					contextClass = Class.forName(DEFAULT_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);
    			}
    		}
    		return (ConfigurableApplicationContext) BeanUtils.instantiateClass(contextClass);
    	}

spring boot是根据不同的webApplicationType的类型，来创建不同的ApplicationContext的。

### prepareContext —— 准备上下文 ###

private void prepareContext(ConfigurableApplicationContext context,
    			ConfigurableEnvironment environment, SpringApplicationRunListeners listeners,
    			ApplicationArguments applicationArguments, Banner printedBanner) {
    		// 对ApplicationContext设置环境变量；
    		context.setEnvironment(environment);
    		// 配置属性ResourceLoader和ClassLoader属性；
    		postProcessApplicationContext(context);
    		// 循环初始化继承ApplicationContextInitializer接口的类
    		applyInitializers(context);
    		listeners.contextPrepared(context);
    		if (this.logStartupInfo) {
    			logStartupInfo(context.getParent() == null);
    			logStartupProfileInfo(context);
    		}
    
    		// Add boot specific singleton beans
    		context.getBeanFactory().registerSingleton("springApplicationArguments",
    				applicationArguments);
    		if (printedBanner != null) {
    			context.getBeanFactory().registerSingleton("springBootBanner", printedBanner);
    		}
    
    		// Load the sources
    		Set<Object> sources = getAllSources();
    		Assert.notEmpty(sources, "Sources must not be empty");
    		load(context, sources.toArray(new Object[0]));
    		listeners.contextLoaded(context);
    	}
    	
    	@Override
    	public void setEnvironment(ConfigurableEnvironment environment) {
    		super.setEnvironment(environment);
    		this.reader.setEnvironment(environment);
    		this.scanner.setEnvironment(environment);
    	}

**加粗样式**

### refreshContext —— 刷新上下文 ###

private void refreshContext(ConfigurableApplicationContext context) {
    		refresh(context);
    		if (this.registerShutdownHook) {
    			try {
    				context.registerShutdownHook();
    			}
    			catch (AccessControlException ex) {
    				// Not allowed in some environments.
    			}
    		}
    	}
    @Override
    	public void refresh() throws BeansException, IllegalStateException {
    		synchronized (this.startupShutdownMonitor) {
    			// 准备刷新的上下文环境
    			prepareRefresh();
    
    			// 初始化BeanFactory
    			ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory();
    
    			// 对BeanFactory进行各种功能填充
    			prepareBeanFactory(beanFactory);
    
    			try {
    				// 子类覆盖方法做额外的处理
    				postProcessBeanFactory(beanFactory);
    
    				// 激活各种BeanFactory处理器
    				invokeBeanFactoryPostProcessors(beanFactory);
    
    				// 注册拦截Bean创建的Bean处理，这里只是注册，真正调用是再拿去Bean的时候
    				registerBeanPostProcessors(beanFactory);
    
    				// 为上下文初始化Message源，即不同语言的消息体，国际化处理
    				initMessageSource();
    
    				// 初始化应用消息广播器，并放到applicationEventMulticaster bean中
    				initApplicationEventMulticaster();
    
    				// 留给子类来初始化其他bean
    				onRefresh();
    
    				// 在所有注册的bean中查找Listener bean，注册到消息广播中
    				registerListeners();
    
    				// 初始化剩下的单实例（非惰性）
    				finishBeanFactoryInitialization(beanFactory);
    
    				// 完成刷新过程，通知生命周期处理器lifecycleProcessor刷新过程，同时发出ContextRefreshEvent通知别人
    				finishRefresh();
    			}
    
    			catch (BeansException ex) {
    				if (logger.isWarnEnabled()) {
    					logger.warn("Exception encountered during context initialization - " +
    							"cancelling refresh attempt: " + ex);
    				}
    
    				// 销毁已经创建的单例Bean, 以避免资源占用.
    				destroyBeans();
    
    				// 取消refresh操作, 重置active标志. 
    				cancelRefresh(ex);
    
    				// Propagate exception to caller.
    				throw ex;
    			}
    
    			finally {
    				// Reset common introspection caches in Spring's core, since we
    				// might not ever need metadata for singleton beans anymore...
    				// 重置Spring的核心缓存
    				resetCommonCaches();
    			}
    		}
    	}

### afterRefresh —— 刷新上下文后 ###

protected void afterRefresh(ConfigurableApplicationContext context,
    			ApplicationArguments args) {
    	}

上面的refresh() 便是构建IoC的最重要的一步

# 总结 #

> 参考博文： [https://blog.csdn.net/u010811939/article/details/80592461 ][https_blog.csdn.net_u010811939_article_details_80592461]

概述：

*  构造SpringApplication的实例（时序图步骤1-2）
 *  调用SpringApplication.run()方法（时序图步骤3）
    
     *  构造SpringApplicationRunListeners 实例（时序图步骤3.1.1）
     *  发布ApplicationStartedEvent事件（时序图步骤3.1.2）
     *  SpringApplicationRunListeners 实例准备环境信息（时序图步骤3.1.3）
     *  创建ApplicationContext对象（时序图步骤3.1.4）
     *  ApplicationContext实例准备环境信息（时序图步骤3.1.5）
     *  刷新的上下文（时序图步骤3.1.6）  
        ![时序图][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2phdmFfeWVz_size_16_color_FFFFFF_t_70]

[Spring 4.x IOC_.BeanFactory _ApplicationContext_WebApplicationContext_BeanFactory]: https://blog.csdn.net/java_yes/article/details/81505865
[Spring 4.x IOC_.BeanFactory _ApplicationContext_WebApplicationContext_ApplicationContext_]: https://blog.csdn.net/java_yes/article/details/81672698
[Spring 4.x IOC_.BeanFactory _ApplicationContext_WebApplicationContext_WebApplicationContext_]: https://blog.csdn.net/java_yes/article/details/81941263
[Spring 4.x IOC_.BeanFactory _ApplicationContext_WebApplicationContext]: https://blog.csdn.net/java_yes/article/details/82107557
[AutoConfigurationImportSelector]: /images/20211122/45d9c51484c84178988fc37748087484.png
[https_blog.csdn.net_u010811939_article_details_80592461]: https://blog.csdn.net/u010811939/article/details/80592461
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2phdmFfeWVz_size_16_color_FFFFFF_t_70]: /images/20211122/39b8b20483f3416c832d09e9e8fd0e4b.png