简介

初始化SpringApplication

public SpringApplication(ResourceLoader resourceLoader, Class... primarySources) {
        this.sources = new LinkedHashSet();
        this.bannerMode = Mode.CONSOLE;
        this.logStartupInfo = true;
        this.addCommandLineProperties = true;
        this.headless = true;
        this.registerShutdownHook = true;
        this.additionalProfiles = new HashSet();
        this.resourceLoader = resourceLoader;
        Assert.notNull(primarySources, "PrimarySources must not be null");
        this.primarySources = new LinkedHashSet(Arrays.asList(primarySources));
        
        // 设置应用类型为 WebApplicationType.SERVLET
        this.webApplicationType = this.deduceWebApplicationType();

        //  META-INF 下的ApplicationContextInitializer
        this.setInitializers(this.getSpringFactoriesInstances(ApplicationContextInitializer.class));
        
        //  META-INF 下的ApplicationListener
        this.setListeners(this.getSpringFactoriesInstances(ApplicationListener.class));

        // 设置启动类
        this.mainApplicationClass = this.deduceMainApplicationClass();
    }

运行SpringApplication

public ConfigurableApplicationContext run(String... args) {
        
        // 做一些启动停止时间的判断；
        StopWatch stopWatch = new StopWatch();
        stopWatch.start();

        //
        ConfigurableApplicationContext context = null;
        Collection<SpringBootExceptionReporter> exceptionReporters = new ArrayList();
        this.configureHeadlessProperty();

        // 事件发布监听器
        SpringApplicationRunListeners listeners = this.getRunListeners(args);
        listeners.starting();

        Collection exceptionReporters;
        try {

            // 应用传入的参数
            ApplicationArguments applicationArguments = new DefaultApplicationArguments(args);
            
            // 环境
            ConfigurableEnvironment environment = this.prepareEnvironment(listeners, applicationArguments);
            this.configureIgnoreBeanInfo(environment);
            Banner printedBanner = this.printBanner(environment);

            // 创建context，webServlet/ reactive/ 非web
            context = this.createApplicationContext();
            exceptionReporters = this.getSpringFactoriesInstances(SpringBootExceptionReporter.class, new Class[]{ConfigurableApplicationContext.class}, context);
            this.prepareContext(context, environment, listeners, applicationArguments, printedBanner);
            
            // 此处会加载IOC且，里面的onrefrsh会启动tomcat
            this.refreshContext(context);
            this.afterRefresh(context, applicationArguments);
            stopWatch.stop();
            if (this.logStartupInfo) {
                (new StartupInfoLogger(this.mainApplicationClass)).logStarted(this.getApplicationLog(), stopWatch);
            }

            listeners.started(context);
            this.callRunners(context, applicationArguments);
        } catch (Throwable var10) {
            this.handleRunFailure(context, var10, exceptionReporters, listeners);
            throw new IllegalStateException(var10);
        }

        try {
            listeners.running(context);
            return context;
        } catch (Throwable var9) {
            this.handleRunFailure(context, var9, exceptionReporters, (SpringApplicationRunListeners)null);
            throw new IllegalStateException(var9);
        }
    }