1.springboot debug

1.初始化SpringApplication

this.resourceLoader = resourceLoader;

Assert.notNull(primarySources,"PrimarySources must not be null");

this.primarySources =new LinkedHashSet<>(Arrays.asList(primarySources));

this.webApplicationType = WebApplicationType.deduceFromClasspath();

setInitializers((Collection) getSpringFactoriesInstances(ApplicationContextInitializer.class));

setListeners((Collection) getSpringFactoriesInstances(ApplicationListener.class));

this.mainApplicationClass = deduceMainApplicationClass();

1.loadSpringFactories类：先加载spring-boot和spring-autoconfig 下的spring-factories  的properties key value

2.实例化ApplicationContextInitializer 和ApplicationListener 的实现类，并加入到当前上下文