springboot启动原理

 1 public ConfigurableApplicationContext run(String... args) {
 2     StopWatch stopWatch = new StopWatch();
 3     stopWatch.start();
 4     ConfigurableApplicationContext context = null;
 5     FailureAnalyzers analyzers = null;
 6     configureHeadlessProperty();
　　　　//获取SpringApplicationRunListeners 从META-INF/spring.factories 下获取 
　　　　//SpringApplicationRunListener.class 这种类型的，并且初始化
 7     SpringApplicationRunListeners listeners = getRunListeners(args);  //就一个EventPunlishRunListener
 8     listeners.starting(); //回调所有starting方法
 9     try {
10           ApplicationArguments applicationArguments = new DefaultApplicationArguments(args); //没有参数
12           ConfigurableEnvironment environment = prepareEnvironment(listeners, applicationArguments);
14           Banner printedBanner = printBanner(environment);
　　　　　　　　//根据环境创建ioc容器
15           context = createApplicationContext();
16           analyzers = new FailureAnalyzers(context); //异常分析报告，下面的try{}catch{}
　　　　　　  //准备上下文环境,将环境保存到ioc容器中，applyInitializers(context);
17           prepareContext(context, environment, listeners, applicationArguments, printedBanner);
19           refreshContext(context); //刷新容器，spring执行流程 相当于所有配置进入 web应用创建tomcat
20           afterRefresh(context, applicationArguments);
21           listeners.finished(context, null);
22           stopWatch.stop();
23           if (this.logStartupInfo) {
24               new StartupInfoLogger(this.mainApplicationClass).logStarted(getApplicationLog(), stopWatch);
26           }
27           return context;
28      }
29       catch (Throwable ex) {
30          handleRunFailure(context, listeners, analyzers, ex);
31          throw new IllegalStateException(ex);
32       }
33  }

protected void applyInitializers(ConfigurableApplicationContext context) {
　　for (ApplicationContextInitializer initializer : getInitializers()) {
	Class<?> requiredType = GenericTypeResolver.resolveTypeArgument(initializer.getClass(), 
　　　　　　　　ApplicationContextInitializer.class);
	Assert.isInstanceOf(requiredType, context, "Unable to call initializer.");
	initializer.initialize(context); //回调之前所有initializer.initialize()
　　}
}