[{"type":"Paragraph","children":[{"text":"springboot启动代码一般如下："}],"slateId":"3F04Nre_kHFpOSlQW_2PN"},{"type":"CodeBlock","activeTabIndex":0,"children":[{"type":"CodeTab","language":"java","name":"","children":[{"text":"@EnableAutoConfiguration //自动装配\n@ComponentScan //自动注入\npublic static void main(String[] args) {\n SpringApplication springApplication = new SpringApplication(xxxApplication.class);\n springApplication.run(args);\n}"}],"slateId":"dXWCasNZ4EmjJD0rFIlxA"}],"slateId":"FAPn4PKCVw0J6FyKDimE_"},{"type":"Paragraph","children":[{"text":""}],"slateId":"0xhz_ybmRO6lkKleDPexI"},{"type":"Heading1","slateId":"PigjWXbXOteEr1Kdeze52","children":[{"text":"一、启动代码"}]},{"type":"Paragraph","slateId":"aNzk_ItG03XBR_ECu0Ch0","children":[{"text":"new SpringApplication()主要执行一些扫描任务"}]},{"type":"CodeBlock","activeTabIndex":0,"children":[{"type":"CodeTab","language":"java","name":"","children":[{"text":"public SpringApplication(ResourceLoader resourceLoader, Class... primarySources) {\n // 将用户自定义的主应用类，如 xxxApplication.class，写入集合中；\n // 这在后面自动注入非常关键，ConfigurationClassPostProcessor.class会先从IOC中取出主配置类，然后递归的扫描主配置类上的注解@ComponentScan、@EnableAutoConfiguration注解\n this.primarySources = new LinkedHashSet<>(Arrays.asList(primarySources));\n // 扫描类路径下所有ApplicationContextInitializer.class\n setInitializers((Collection) getSpringFactoriesInstances(ApplicationContextInitializer.class));\n // 扫描类路径下所有ApplicationListener.class\n setListeners((Collection) getSpringFactoriesInstances(ApplicationListener.class));\n this.mainApplicationClass = deduceMainApplicationClass();\n}"}],"slateId":"ph4BupKX7ypcHIsllgh_c"}],"slateId":"usp5zMTBzEvIJqw36Hkl1"},{"type":"Paragraph","children":[{"text":"SpringApplication.run() 的关键片段："}],"slateId":"4ICdbTPJ90Y4QhNqQET0B"},{"type":"CodeBlock","activeTabIndex":0,"children":[{"type":"CodeTab","language":"java","name":"","children":[{"text":"public ConfigurableApplicationContext run(String... args) {\n // 创建一个空的IOC容器\n ConfigurableApplicationContext context = null;\n \n //获取SpringApplicationRunListeners, 从类路径下META-INF/spring/spring.factories获取\n 作用：使用观察者模式，在spring初始化的特定阶段，调用不同的方法\n spring默认注册了EventPublishingRunListener，用于发送下述的各种Event事件\n SpringApplicationRunListeners listeners = this.getRunListeners(args);\n listeners.starting(bootstrapContext, this.mainApplicationClass);\n \n // 封装命令行参数\n ApplicationArguments applicationArguments = new DefaultApplicationArguments(args);\n \n //重要：创建IOC容器，根据Spring应用类型创建ApplicationContext，一般都为Servlet类型\n context = this.createApplicationContext();\n \n // a.主要是调用 this.applyInitializers(context); \n // 将new ConfigurableApplicationContext()构造函数中扫描到的ApplicationContextInitializer.class都执行一遍\n // b.将用户自定义的主配置类实例化为BD，注入BeanFactory\n this.prepareContext(bootstrapContext, context, environment, listeners, applicationArguments, printedBanner);\n\n // 核心：初始化IOC容器，将各种Bean加载进容器\n refreshContext(context); \n\n afterRefresh(context, applicationArguments); // 默认为空,用户可以通过接口实现\n\n // ⏱️ 【关键点】refresh() 已完全结束！此时 ContextRefreshedEvent 已发布！此时所有Bean已经完成初始化、且非懒加载的单例Bean已经注入IOC容器\n\n // 从IOC（即，BeanFactory）容器中获取所有Runner执（CommandLineRunner / ApplicationRunner的实现类），并执行run方法\n callRunners(context, applicationArguments); \n\n // 👇 Runner 执行完后，才发布 ApplicationReadyEvent\n if (context.isRunning()) {\n listeners.ready(context, startup.ready()); // ← listener中包含观察者EventPublishingRunListener，其在这会发布 ApplicationReadyEvent事件\n }\n \n // 完全启动完成后，返回IOC容器\n return context;\n}"}],"slateId":"mqznA-yBzDUeF7fMrXqnS"}],"slateId":"vIUezcAS3U25nG3G3fIq5"},{"type":"Paragraph","children":[{"text":"context = this.createApplicationContext()相关源码的展开："}],"slateId":"Wajvr_b8fkZraCvHS2uoG"},{"type":"CodeBlock","activeTabIndex":0,"children":[{"type":"CodeTab","language":"java","name":"","children":[{"text":"protected ConfigurableApplicationContext createApplicationContext() {\n return this.applicationContextFactory.create(this.properties.getWebApplicationType());\n}\n\n// 根据当前应用的 Web 类型（Servlet、Reactive 或 NONE），创建对应的 ConfigurableApplicationContext 实例\n//通常为Servlet类型： WebApplicationType.SERVLET ----> AnnotationConfigServletWebServerApplicationContext.class\n\n// 其构造函数注册AnnotatedBeanDefinitionReader.class\npublic AnnotationConfigServletWebServerApplicationContext() {\n this.reader = new AnnotatedBeanDefinitionReader(this); // ← 关键！\n this.scanner = new ClassPathBeanDefinitionScanner(this);\n}\n\n// Reader使用工具类注册多个作用于各种注解的BeanPostProcessor\npublic AnnotatedBeanDefinitionReader(BeanDefinitionRegistry registry, Environment environment) {\n ........\n AnnotationConfigUtils.registerAnnotationConfigProcessors(this.registry);\n}\n\npublic static Set registerAnnotationConfigProcessors(\n BeanDefinitionRegistry registry, @Nullable Object source) {\n\n // 1. 注册 ConfigurationClassPostProcessor（最关键！）\n if (!registry.containsBeanDefinition(CONFIGURATION_ANNOTATION_PROCESSOR_BEAN_NAME)) {\n RootBeanDefinition def = new RootBeanDefinition(ConfigurationClassPostProcessor.class);\n def.setSource(source);\n beanDefs.add(registerPostProcessor(registry, def, CONFIGURATION_ANNOTATION_PROCESSOR_BEAN_NAME));\n }\n\n // 2. 注册 CommonAnnotationBeanPostProcessor（支持 @PostConstruct 等）\n // 3. 注册 AutowiredAnnotationBeanPostProcessor（支持 @Autowired）\n // 4. 注册 PersistenceAnnotationBeanPostProcessor（JPA）\n // 5. 注册 EventListenerMethodProcessor 和 DefaultEventListenerFactory（@EventListener）\n\n return beanDefs;\n}"}],"slateId":"kc0VJQCYN_QlbmoKF6S7I"}],"slateId":"suebZE0-E1ss4qW01pqJQ"},{"type":"Paragraph","children":[{"text":"a.这里的ConfigurationClassPostProcessor.class实现了BeanDefinitionRegistryPostProcessor接口，"}],"slateId":"rq2ZU-N-4QlsNp6kzB-Oe"},{"type":"Paragraph","slateId":"jxlxWKdrE7iWmGlAcr9G6","children":[{"text":"并作为一个BeanDefinition注入IOC容器，并在后续refresh()的invokeBeanFactoryPostProcessors()方法中调用(即第5步)"}]},{"type":"Paragraph","slateId":"Jcn4lmwmxIuPbv1pq_gcv","children":[{"text":"b.同时ConfigurationClassPostProcessor.class实现了PriorityOrdered接口"}]},{"type":"Paragraph","slateId":"s-Qi_uznN1gRlP8NpkoY1","children":[{"text":"在refresh()的步骤5中，会被率先调用"}]},{"type":"Paragraph","slateId":"2XY8wzqg6otpnqQ21sA_0","children":[{"text":"！！！这是实现自动装配和自动配置的关键。"}]},{"type":"Paragraph","slateId":"ShG4xP4gG16YE0eB1FZhy","children":[{"text":""}]},{"type":"Paragraph","slateId":"ecWS6GhjfZXcDbq4cMYsD","children":[{"text":"this.prepareContext();的相关源码展开:"}]},{"type":"CodeBlock","activeTabIndex":0,"children":[{"type":"CodeTab","language":"java","name":"","children":[{"text":"private void prepareContext(DefaultBootstrapContext bootstrapContext, ConfigurableApplicationContext context,\n ConfigurableEnvironment environment, SpringApplicationRunListeners listeners,\n ApplicationArguments applicationArguments, Banner printedBanner) {\n ....\n // 将new ConfigurableApplicationContext()构造函数中扫描到的ApplicationContextInitializer.class都执行一遍\n applyInitializers(context);\n .....\n if (!AotDetector.useGeneratedArtifacts()) {\n // Load the sources\n // SpringApplication构造函数中赋值的this.primarySources成员变量中取出用户自定义的主配置类,如xxxApplication.class\n Set