Spring Boot启动过程

public ConfigurableApplicationContext run(String... args) {
    StopWatch stopWatch = new StopWatch();
    stopWatch.start();
    ConfigurableApplicationContext context = null;
    FailureAnalyzers analyzers = null;
    configureHeadlessProperty();
                //1.创建了应用的监听器SpringApplicationRunListeners并开始监听
    SpringApplicationRunListeners listeners = getRunListeners(args);
    listeners.starting();
    try {
                //2.创建⼀个DefaultApplicationArguments对象,它持有着args参数，就是main函数传进来的参数.调⽤prepareEnvironment⽅法
      ApplicationArguments applicationArguments = new DefaultApplicationArguments(
          args);
               //3.加载SpringBoot配置环境(ConfigurableEnvironment)，如果是通过web容器发布，会加载StandardEnvironment
      ConfigurableEnvironment environment = prepareEnvironment(listeners,
          applicationArguments);
               //4.打印banner
      Banner printedBanner = printBanner(environment);
               //5.创建run方法的返回对象：ConfigurableApplicationContext(应用配置上下文)
      context = createApplicationContext();
      analyzers = new FailureAnalyzers(context);
              //6.回到run方法内，prepareContext方法将listeners、environment、applicationArguments、banner等重
              //要组件与上下文对象关联
      prepareContext(context, environment, listeners, applicationArguments,
          printedBanner);
              //7.接下来的refreshContext(context)方法(初始化方法如下)将是实现spring-boot-starter-*(mybatis、
              //redis等)自动化配置的关键，包括spring.factories的加载，bean的实例化等核心工作。
      refreshContext(context);
      afterRefresh(context, applicationArguments);
      listeners.finished(context, null);
      stopWatch.stop();
      return context;
    }
    catch (Throwable ex) {
      handleRunFailure(context, listeners, analyzers, ex);
      throw new IllegalStateException(ex);
    }
  }