【Springboot总结】19 嵌入式Servlet容器启动原理

1、SpringBoot应用启动运行run方法

2、refreshContext(context)  SpringBoot创建IOC容器,创建IOC容器对象，并初始化容器，创建容器中的每一个组件

3、refresh(context)  刷新刚才创建好的ioc容器

public void refresh() throws BeansException, IllegalStateException {
   synchronized (this.startupShutdownMonitor) {
      // Prepare this context for refreshing.
      prepareRefresh();

      // Tell the subclass to refresh the internal bean factory.
      ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory();

      // Prepare the bean factory for use in this context.
      prepareBeanFactory(beanFactory);

      try {
         // Allows post-processing of the bean factory in context subclasses.
         postProcessBeanFactory(beanFactory);

         // Invoke factory processors registered as beans in the context.
         invokeBeanFactoryPostProcessors(beanFactory);

         // Register bean processors that intercept bean creation.
         registerBeanPostProcessors(beanFactory);

         // Initialize message source for this context.
         initMessageSource();

         // Initialize event multicaster for this context.
         initApplicationEventMulticaster();

         // Initialize other special beans in specific context subclasses.
         onRefresh();

         // Check for listener beans and register them.
         registerListeners();

         // Instantiate all remaining (non-lazy-init) singletons.
         finishBeanFactoryInitialization(beanFactory);

         // Last step: publish corresponding event.
         finishRefresh();
      }

      catch (BeansException ex) {
         if (logger.isWarnEnabled()) {
            logger.warn("Exception encountered during context initialization - " +
                  "cancelling refresh attempt: " + ex);
         }

         // Destroy already created singletons to avoid dangling resources.
         destroyBeans();

         // Reset 'active' flag.
         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...
         resetCommonCaches();
      }
   }
}

4、web ioc容器会获取嵌入式的Servlet容器工厂

EmbeddedServletContainerFactory containerFactory = getEmbeddedServletContainerFactory();

5. 使用容器工厂获取嵌入式的Servlet容器

this.embeddedServletContainer = containerFactory .getEmbeddedServletContainer(getSelfInitializer());

 6. 嵌入式的Servlet容器创建对象并启动Servlet容器

 

从ioc容器中获取EmbeddedServletContainerFactory 组件；EmbeddedServletContainerFactory创建对象，后置处理器一看是这个对象，就获取所有的定制器来先定制Servlet容器的相关配置；