spring 容器的創建對應 SpringApplication 中 run 中調用的 createApplicationContext 方法。這里創建了一個 web 容器，接下就進去 prepareContext 容器準備階段：

private void prepareContext(ConfigurableApplicationContext context, ConfigurableEnvironment environment, SpringApplicationRunListeners listeners, ApplicationArguments applicationArguments, Banner printedBanner) { //為容器設置環境 context.setEnvironment(environment); //這里的空實現留給開發者擴展，設置數據轉換的ConversionService postProcessApplicationContext(context); //執行容器中的 Initializers 的 initialize 方法 applyInitializers(context); listeners.contextPrepared(context); if (this.logStartupInfo) { logStartupInfo(context.getParent() == null); logStartupProfileInfo(context); } // Add boot specific singleton 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 Set<Object> sources = getAllSources(); Assert.notEmpty(sources, 'Sources must not be empty'); load(context, sources.toArray(new Object[0])); listeners.contextLoaded(context); }

看一下這里的 load 方法,這里主要把我們的啟動類作為 Bean 注冊到了 Spring 的容器中。

protected void load(ApplicationContext context, Object[] sources) { if (logger.isDebugEnabled()) { logger.debug('Loading source ' + StringUtils.arrayToCommaDelimitedString(sources)); } BeanDefinitionLoader loader = createBeanDefinitionLoader(getBeanDefinitionRegistry(context), sources); if (this.beanNameGenerator != null) { loader.setBeanNameGenerator(this.beanNameGenerator); } if (this.resourceLoader != null) { loader.setResourceLoader(this.resourceLoader); } if (this.environment != null) { loader.setEnvironment(this.environment); } loader.load(); }

/** * Load the sources into the reader. * @return the number of loaded beans */ int load() { int count = 0; for (Object source : this.sources) { count += load(source); } return count; } private int load(Object source) { Assert.notNull(source, 'Source must not be null'); if (source instanceof Class<?>) { return load((Class<?>) source); } if (source instanceof Resource) { return load((Resource) source); } if (source instanceof Package) { return load((Package) source); } if (source instanceof CharSequence) { return load((CharSequence) source); } throw new IllegalArgumentException('Invalid source type ' + source.getClass()); } private int load(Class<?> source) { if (isGroovyPresent() && GroovyBeanDefinitionSource.class.isAssignableFrom(source)) { // Any GroovyLoaders added in beans{} DSL can contribute beans here GroovyBeanDefinitionSource loader = BeanUtils.instantiateClass(source, GroovyBeanDefinitionSource.class); load(loader); } if (isEligible(source)) { this.annotatedReader.register(source); return 1; } return 0; }

再來看下 contextLoaded 方法，這里將上下文設置到監聽器中，同時也把監聽器添加到上下文中。最后發布了一個 ApplicationPreparedEvent 事件。

public void contextLoaded(ConfigurableApplicationContext context) { for (ApplicationListener<?> listener : this.application.getListeners()) { if (listener instanceof ApplicationContextAware) {((ApplicationContextAware) listener).setApplicationContext(context); } context.addApplicationListener(listener); } this.initialMulticaster.multicastEvent(new ApplicationPreparedEvent(this.application, this.args, context)); }

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