什么时候创建嵌入式的Servlet容器工厂?什么时候获取嵌入式的Servlet容器并启动Tomcat;

获取嵌入式的Servlet容器工厂:

1. springboot应用启动运行run方法
2. refreshContext(context):springBoot刷新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];如果是web应用创建web.servlet.context.AnnotationConfigServletWebServerApplicationContext, 否则,创建默认的AnnotationConfigReactiveWebServerApplicationContext;
3. refresh(Context)刷新刚才创建的容器.

@Override
    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. onRefresh(); web的IOC容器重写了onfresh方法.
   web ioc容器会创建嵌入式的servlet容器:createWebServer();
5. ServletWebServerFactory factory = getWebServerFactory();
6. 获取嵌入式的servlet容器工厂,
   从ioc容器中获取ServletWebServerFactory组件,TomcatServletWebServerFactory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
7. 使用容器工厂获取嵌入式的servlet容器
8. 嵌入式的servlet容器创建对象,并启动servlet容器,

先启动嵌入式的servlet容器,在将ioc容器中剩下的没有创建出的对象获取出来.

ioc容器启动创建嵌入式的servlet容器.