Spring Boot系列（四）：Spring Boot源码解析

public SpringApplication(ResourceLoader resourceLoader, Class<?>... primarySources) {
        this.resourceLoader = resourceLoader;
        Assert.notNull(primarySources, "PrimarySources must not be null");
        //设置主配置类 我们自己写的Spring Boot的启动类
        this.primarySources = new LinkedHashSet<>(Arrays.asList(primarySources));
        //设置web应用的类型
        this.webApplicationType = WebApplicationType.deduceFromClasspath();
        //设置容器初始化器(ApplicationContextInitializer类型的)
        setInitializers((Collection) getSpringFactoriesInstances(ApplicationContextInitializer.class));
        //把监听器设置到SpringApplication中[ApplicationListener]
        setListeners((Collection) getSpringFactoriesInstances(ApplicationListener.class));
        //设置主配置类
        this.mainApplicationClass = deduceMainApplicationClass();
    }

public ConfigurableApplicationContext run(String... args) {
        StopWatch stopWatch = new StopWatch();
        stopWatch.start();
        //容器对象
        ConfigurableApplicationContext context = null;
        Collection<SpringBootExceptionReporter> exceptionReporters = new ArrayList<>();
        configureHeadlessProperty();
        //去META-INFO/spring.factories中获取SpringApplicationRunListener监听器(事件发布监听器)
        SpringApplicationRunListeners listeners = getRunListeners(args);
        //发布容器starting事件(通过spring的事件多播器)
        listeners.starting();
        try {
            //封装命令行参数
            ApplicationArguments applicationArguments = new DefaultApplicationArguments(args);
            /**
             * 准备容器环境
             * 1: 获取或者创建环境
             * 2：把命令行参数设置到环境中
             * 3：通过监听器发布环境准备事件
             */
            ConfigurableEnvironment environment = prepareEnvironment(listeners, applicationArguments);
            configureIgnoreBeanInfo(environment);
            //打印Springboot的图标
            Banner printedBanner = printBanner(environment);
            //创建容器根据webApplicationType来创建容器(通过反射创建)
            context = createApplicationContext();
            exceptionReporters = getSpringFactoriesInstances(SpringBootExceptionReporter.class,
                    new Class[] { ConfigurableApplicationContext.class }, context);
            /**
             * 准备上下文
             * 1：把环境设置到容器中
             * 2: 循环调用ApplicationContextInitializer进行容器初始化工作
             * 3: 发布容器上下文准备完成事件
             * 4: 注册关于Springboot特性的相关单例Bean
             * 5: 发布容器上下文加载完毕事件
             */
            prepareContext(context, environment, listeners, applicationArguments, printedBanner);
            refreshContext(context);
            //运行ApplicationRunner和CommandLineRunner
            afterRefresh(context, applicationArguments);
            stopWatch.stop();
            if (this.logStartupInfo) {
                new StartupInfoLogger(this.mainApplicationClass).logStarted(getApplicationLog(), stopWatch);
            }
            //发布容器启动事件
            listeners.started(context);
            //运行ApplicationRunner和CommandLineRunner
            callRunners(context, applicationArguments);
        }
        catch (Throwable ex) {
            //出现异常调用异常分析保护类进行分析
            handleRunFailure(context, ex, exceptionReporters, listeners);
            throw new IllegalStateException(ex);
        }

        try {
            //发布容器运行事件
            listeners.running(context);
        }
        catch (Throwable ex) {
            handleRunFailure(context, ex, exceptionReporters, null);
            throw new IllegalStateException(ex);
        }
        return context;
    }