Spring启动流程

// 第一次进入拿到的是ConfigurationClassPostProcessor 的 BeanDefinition 与扫描相关//当前循环 List<BeanDefinitionRegistryPostProcessor> 放入  实现PriorityOrdered排好序的BeanDefinitionRegistryPostProcessor（beanFactory 后置处理器）   registryProcessors.addAll(currentRegistryProcessors);

// 增强配置类，代理加了Configuration注解的配置类（cglb 动态代理生成代理类，修改BeanDifinition的beanClass属性指向生成的代理类）// Configuration 的作用是在-->某个用@Bean 注解注释的方法内部有调用其他@Bean 注解注释的方法时，是用该配置类的代理类去执行调用方法，那么在执行之前会执行代理逻辑，判断被调用的bean是不是已经创建出来了，如果是那就不需要再创建，直接从单例池获取  enhanceConfigurationClasses(beanFactory);

注册CommonAnnotationBeanPostProcessor类型的BeanDefinition会处理bean中的@Resource注解

// ConfigurationClassPostProcessor 会解析配置类  processConfigBeanDefinitions(registry);

prepareBeanFactory(beanFactory); 在这个步骤会加入ApplicationListenerDetector，这里也加了一次，不是重复了吗？

// 执行完BeanDefinitionRegistryPostProcessor的postProcessBeanDefinitionRegistry()方法后，   // 再执行BeanDefinitionRegistryPostProcessor的postProcessBeanFactory()方法   font color=\"#b71c1c\

// 添加了事件监听器后，判断是否有earlyApplicationEvents，如果有就使用事件广播器发布earlyApplicationEvents\t\t// earlyApplicationEvents表示在事件广播器还没生成好之前ApplicationContext所发布的事件\t\tSet<ApplicationEvent> earlyEventsToProcess = this.earlyApplicationEvents;\t\tthis.earlyApplicationEvents = null;\t\tif (!CollectionUtils.isEmpty(earlyEventsToProcess)) {\t\t\tfor (ApplicationEvent earlyEvent : earlyEventsToProcess) {\t\t\t\tgetApplicationEventMulticaster().multicastEvent(earlyEvent);\t\t\t}\t\t}

子流程

 if (this.applicationEventMulticaster != null) {   this.applicationEventMulticaster.addApplicationListener(listener);  }  this.applicationListeners.add(listener);

AnnotationConfigApplicationContext applicationContext = new AnnotationConfigApplicationContext();  applicationContext.register(AppConfig.class);  applicationContext.addBeanFactoryPostProcessor(new BeanFactoryPostProcessor() {   @Override   public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {   }  });  applicationContext.refresh();

继承 SmartInitializingSingleton

prepareRefresh()

关联

// ApplicationListenerDetector负责把ApplicantsListener类型的Bean注册到ApplicationContext中  beanFactory.addBeanPostProcessor(new ApplicationListenerDetector(this));

ConfigurationClassPostProcessor.postProcessBeanFactory()

解析配置类会扫描，扫描出程序员自己定义出来的BeanFactoryPostProcessor

注册AutowiredAnnotationBeanPostProcessor类型的BeanDefinition会处理bean中的@Value @Autowired注解

  this.beanFactory = new DefaultListableBeanFactory();

  // 准备BeanFactory   // 1. 设置BeanFactory的类加载器、SpringEL表达式解析器、类型转化注册器   // 2. 添加三个BeanPostProcessor，注意是具体的BeanPostProcessor实例对象   // 3. 记录ignoreDependencyInterface   // 4. 记录ResolvableDependency   // 5. 添加三个单例Bean   prepareBeanFactory(beanFactory);

加入beanFactory的beanPostProcessors属性前会移除（根据ApplicationListenerDetector的equals()方法）之前加的  this.beanPostProcessors.remove(beanPostProcessor);  this.beanPostProcessors.add(beanPostProcessor);

// 模板方法比如子类可以把ServletContext中的参数对设置到Environment(spring环境容器中)  initPropertySources();

refresh();

//font color=\"#b71c1c\

// 设置lifecycleProcessor，默认为DefaultLifecycleProcessor\t\tinitLifecycleProcessor();

this.scanner = new ClassPathBeanDefinitionScanner(this);

afterSingletonsInstantiated()// 所有单例bean 实例化后调用

注册EventListenerMethodProcessor类型的BeanDefinition，用来处理@EventListener注解的

当前未执行

// 将扫描到的BeanPostProcessors实例化并排序，并添加到BeanFactory的beanPostProcessors属性中去    registerBeanPostProcessors(beanFactory);

// 子类来设置一下BeanFactory与web相关    postProcessBeanFactory(beanFactory);

publishEvent(new ContextRefreshedEvent(this));// 发布容器启动完成事件

AnnotationConfigApplicationContext applicationContext = new AnnotationConfigApplicationContext(AppConfig.class);初始化容器开始

//实现ImportAware实现类上没有@Component，通过其他类@Import导入，可以获取到导入类的注解信息\t\tbeanFactory.addBeanPostProcessor(new ImportAwareBeanPostProcessor(beanFactory));

beanFactory.setBeanClassLoader(getClassLoader());

启动结束

//最后加入ApplicationListenerDetector 这个BeanPostProcessorbeanFactory.addBeanPostProcessor(new ApplicationListenerDetector(applicationContext));

currentRegistryProcessors.clear();

registerDefaultFilters();

//在初始化后 将ApplicationListener 加入applicationContext 的事件广播器中Boolean flag = this.singletonNames.get(beanName);   if (Boolean.TRUE.equals(flag)) {    this.applicationContext.addApplicationListener((ApplicationListener<?>) bean);   }

// 把定义的ApplicationListener的Bean对象，设置到ApplicationContext中去，并执行在此之前所发布的事件    registerListeners();

// 将单例非懒加载bean 实例化放入单例池// 流程图请看'spring实例化单例bean'    finishBeanFactoryInitialization(beanFactory);

// Spring5.3中新增的功能，可以选择是否开启Spel功能，shouldIgnoreSpel默认为false，表示开启\t\tif (!shouldIgnoreSpel) {\t\t\tbeanFactory.setBeanExpressionResolver(new StandardBeanExpressionResolver(beanFactory.getBeanClassLoader()));\t\t}

@Override\tpublic boolean equals(@Nullable Object other) {\t\treturn (this == other || (other instanceof ApplicationListenerDetector &&\t\t\t\tthis.applicationContext == ((ApplicationListenerDetector) other).applicationContext));\t}

getLifecycleProcessor().onRefresh();// 调用LifecycleBean的start()

this();

// beanFactoryPostProcessors集合一般情况下都是空的，除非我们手动调用容器的addBeanFactoryPostProcessor方法添加了   // beanFactoryPostProcessors中可能包含了：普通BeanFactoryPostProcessor对象和BeanDefinitionRegistryPostProcessor对象   // 对于BeanDefinitionRegistryPostProcessor对象，会执行自己的postProcessBeanDefinitionRegistry()方法   for (BeanFactoryPostProcessor postProcessor : beanFactoryPostProcessors) {    if (postProcessor instanceof BeanDefinitionRegistryPostProcessor) {     BeanDefinitionRegistryPostProcessor registryProcessor =       (BeanDefinitionRegistryPostProcessor) postProcessor;     registryProcessor.postProcessBeanDefinitionRegistry(registry);     registryProcessors.add(registryProcessor);    }    else {     regularPostProcessors.add(postProcessor);    }   }

 // 组成一个BeanPostProcessor，用来处理EnvironmentAware、EmbeddedValueResolverAware等回调  beanFactory.addBeanPostProcessor(new ApplicationContextAwareProcessor(this));

this.reader = new AnnotatedBeanDefinitionReader(this);  

getEnvironment().validateRequiredProperties();//验证环境变量中是否有对应键值存在

// 注册@Component对应的AnnotationTypeFilter\t\tthis.includeFilters.add(new AnnotationTypeFilter(Component.class));

finishRefresh();

// Invoke factory processors registered as beans in the context.    // BeanFactory准备好了之后，执行BeanFactoryPostProcessor，开始对BeanFactory进行处理    // 默认情况下:    // 此时beanFactory的beanDefinitionMap中有6个BeanDefinition，5个基础BeanDefinition+AppConfig的BeanDefinition    // 而这6个中只有一个BeanFactoryPostProcessor：ConfigurationClassPostProcessor    // 这里会执行ConfigurationClassPostProcessor进行@Component的扫描，扫描得到BeanDefinition，并注册到beanFactory中    // 注意：扫描的过程中可能又会扫描出其他的BeanFactoryPostProcessor，那么这些BeanFactoryPostProcessor也得在这一步执行    invokeBeanFactoryPostProcessors(beanFactory);  // scanner.scan()

if (processedBeans.contains(ppName)) {    // skip - already processed in first phase above   }按照之前特殊BeanFactory后置处理器一样 排序（排序之前要排除掉已经执行过后置方法的BeanFactory后置处理器）执行后置方法postProcessor.postProcessBeanFactory(beanFactory)

// 给子类的模板方法没用    onRefresh()

// 执行手动添加的普通BeanFactoryPostProcessor的postProcessBeanFactory()方法//也就是一开始我们手动调用容器的addBeanFactoryPostProcessor方法添加了   invokeBeanFactoryPostProcessors(font color=\"#b71c1c\

当前未执行，只代表有关联

// 放入applicationContext 的事件广播器applicationEventMulticastercontext.addApplicationListener(applicationListener);

因为上面的步骤完成了扫描，这个过程中程序员可能自己定义了一些BeanPostProcessor，在这一步骤就会把BeanFactory中所有的BeanPostProcessor 找出来并实例化加到BeanFactory的beanPostProcessors属性中去，并且按照是否实现PriorityOrdered ，Ordered 接口排序

添加beanFactory.ignoreDependencyInterface的属性如果一个bean属性对应的set方法在ignoredDependencyInterfaces接口中被定义了，则该属性不会进行自动注入（是Spring中的自动注入@Bean(autowire = Autowire.BY_NAME/BY_TYPE)，不是@Autowired）beanFactory.ignoreDependencyInterface(EnvironmentAware.class);  beanFactory.ignoreDependencyInterface(EmbeddedValueResolverAware.class);  beanFactory.ignoreDependencyInterface(ResourceLoaderAware.class);  beanFactory.ignoreDependencyInterface(ApplicationEventPublisherAware.class);  beanFactory.ignoreDependencyInterface(MessageSourceAware.class);  beanFactory.ignoreDependencyInterface(ApplicationContextAware.class);  beanFactory.ignoreDependencyInterface(ApplicationStartupAware.class);