SpringBoot启动流程分析

前景提示

　　@ComponentScan  的处理都放在org.springframework.context.annotation.ConfigurationClassParser#doProcessConfigurationClass

1.创建SpringApplication对象

private void initialize(Object[] sources) {
        if (sources != null && sources.length > 0) {
            this.sources.addAll(Arrays.asList(sources));
        }
　　　　　　　//判断当前是否是web应用
        this.webEnvironment = deduceWebEnvironment();
　　　　　　　//从类路径下找到META-INF/spring
        setInitializers((Collection) getSpringFactoriesInstances(
                ApplicationContextInitializer.class));
        setListeners((Collection) getSpringFactoriesInstances(ApplicationListener.class));
        this.mainApplicationClass = deduceMainApplicationClass();
    }

        StopWatch stopWatch = new StopWatch();
        stopWatch.start();
        ConfigurableApplicationContext context = null;
        configureHeadlessProperty();
　　　　　　//获取liestener 从类路径下META-INF/spring.factoise下获取
        SpringApplicationRunListeners listeners = getRunListeners(args);
　　　　　　//回调starting方法
        listeners.started();
        try {
　　　　　　　　//封装命令行参数
            ApplicationArguments applicationArguments = new DefaultApplicationArguments(
                    args);
            context = createAndRefreshContext(listeners, applicationArguments);
            afterRefresh(context, applicationArguments);
            listeners.finished(context, null);
            stopWatch.stop();
            if (this.logStartupInfo) {
                new StartupInfoLogger(this.mainApplicationClass)
                        .logStarted(getApplicationLog(), stopWatch);
            }
            return context;
        }
        catch (Throwable ex) {
            handleRunFailure(context, listeners, ex);
            throw new IllegalStateException(ex);
        }