SpringBoot大致启动流程
以main方法为入口进入:
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主线流程到此结束，接下来重点看 6，7，8这三个方法中详细的代码流程，首先是prepareContext进行上下文预处理:
private void prepareContext(ConfigurableApplicationContext context, ConfigurableEnvironment environment, SpringApplicationRunListeners listeners, ApplicationArguments applicationArguments, Banner printedBanner) { context.setEnvironment(environment);//为上下文设置Environment this.postProcessApplicationContext(context); this.applyInitializers(context); listeners.contextPrepared(context); if (this.logStartupInfo) { this.logStartupInfo(context.getParent() == null); this.logStartupProfileInfo(context); } ConfigurableListableBeanFactory beanFactory = context.getBeanFactory(); beanFactory.registerSingleton("springApplicationArguments", applicationArguments); if (printedBanner != null) { beanFactory.registerSingleton("springBootBanner", printedBanner);//注册banner单例 } if (beanFactory instanceof DefaultListableBeanFactory) { ((DefaultListableBeanFactory)beanFactory).setAllowBeanDefinitionOverriding(this.allowBeanDefinitionOverriding); } if (this.lazyInitialization) { context.addBeanFactoryPostProcessor(new LazyInitializationBeanFactoryPostProcessor()); } Set<Object> sources = this.getAllSources(); Assert.notEmpty(sources, "Sources must not be empty");//断言 this.load(context, sources.toArray(new Object[0])); listeners.contextLoaded(context); }
之后是refreshContext进行上下文更新:
1 private void refreshContext(ConfigurableApplicationContext context) { 2 this.refresh((ApplicationContext)context); 3 if (this.registerShutdownHook) { 4 try { 5 context.registerShutdownHook(); 6 } catch (AccessControlException var3) { 7 } 8 } 9 10 }
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public void refresh() throws BeansException, IllegalStateException {
synchronized(this.startupShutdownMonitor) {//使用synchronized对象锁锁住整个方法，strtupShutdownMonitor为Object实例对象
this.prepareRefresh();//更新前的数据准备，startupDate设置为当前时间，closed设为false,active设为true
ConfigurableListableBeanFactory beanFactory = this.obtainFreshBeanFactory();
this.prepareBeanFactory(beanFactory);
//进行大量赋值，最终以执行resetCommonCaches结束
try {
this.postProcessBeanFactory(beanFactory);
this.invokeBeanFactoryPostProcessors(beanFactory);
this.registerBeanPostProcessors(beanFactory);
this.initMessageSource();
this.initApplicationEventMulticaster();
this.onRefresh();
this.registerListeners();
this.finishBeanFactoryInitialization(beanFactory);
this.finishRefresh();
} catch (BeansException var9) {
if (this.logger.isWarnEnabled()) {
this.logger.warn("Exception encountered during context initialization - cancelling refresh attempt: " + var9);
}
this.destroyBeans();
this.cancelRefresh(var9);
throw var9;
} finally {
this.resetCommonCaches();
}
}
}
接下来看afterRefresh方法：
1 protected void afterRefresh(ConfigurableApplicationContext context, ApplicationArguments args) { 2 }
afterRefresh方法结束，只有一个空壳方法在这里，应该可以进行自定义拓展；