一：核心代码：
package com.spring; import org.springframework.beans.factory.config.ConfigurableListableBeanFactory; import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; import org.springframework.context.ConfigurableApplicationContext; // 核心注解 @SpringBootApplication public class Application{ public static void main(String[] args) { // 启动springboot ConfigurableApplicationContext run = SpringApplication.run(Application.class, args); } }SpringApplication.run(Application.class, args);内部最终走到这个方法
public static ConfigurableApplicationContext run(Class<?>[] primarySources, String[] args) { return (new SpringApplication(primarySources)).run(args); }二：new SpringApplication(primarySources)：
public SpringApplication(ResourceLoader resourceLoader, Class<?>... primarySources) { this.sources = new LinkedHashSet(); this.bannerMode = Mode.CONSOLE; this.logStartupInfo = true; this.addCommandLineProperties = true; this.addConversionService = true; this.headless = true; this.registerShutdownHook = true; this.additionalProfiles = Collections.emptySet(); this.isCustomEnvironment = false; this.lazyInitialization = false; this.applicationContextFactory = ApplicationContextFactory.DEFAULT; this.applicationStartup = ApplicationStartup.DEFAULT; this.resourceLoader = resourceLoader; Assert.notNull(primarySources, "PrimarySources must not be null"); this.primarySources = new LinkedHashSet(Arrays.asList(primarySources)); // 确定应用程序类型 this.webApplicationType = WebApplicationType.deduceFromClasspath(); this.bootstrapRegistryInitializers = this.getBootstrapRegistryInitializersFromSpringFactories(); // 加载初始化器this.setInitializers(this.getSpringFactoriesInstances(ApplicationContextInitializer.class)); // 加载监听器 this.setListeners(this.getSpringFactoriesInstances(ApplicationListener.class)); // 设置程序运行的主类 this.mainApplicationClass = this.deduceMainApplicationClass(); }三：.run(args)：
public ConfigurableApplicationContext run(String... args) { // 实例化计时器 StopWatch stopWatch = new StopWatch(); // 开始计时 stopWatch.start(); // 获取上下文 DefaultBootstrapContext bootstrapContext = this.createBootstrapContext(); ConfigurableApplicationContext context = null; this.configureHeadlessProperty(); // 创建所有 Spring 运行监听器并发布应用启动事件 SpringApplicationRunListeners listeners = this.getRunListeners(args); // 通过上下文启动监听器 listeners.starting(bootstrapContext, this.mainApplicationClass); try { // 设置应用程序参数 ApplicationArguments applicationArguments = new DefaultApplicationArguments(args); // 准备环境变量 ConfigurableEnvironment environment = this.prepareEnvironment(listeners, bootstrapContext, applicationArguments); // 将 spring.beaninfo.ignore 的默认值值设为true，意思是跳过beanInfo的搜索 this.configureIgnoreBeanInfo(environment); // 打印banner Banner printedBanner = this.printBanner(environment); // 创建应用程序上下文 context = this.createApplicationContext(); context.setApplicationStartup(this.applicationStartup); // 准备上下文环境 this.prepareContext(bootstrapContext, context, environment, listeners, applicationArguments, printedBanner); // 刷新上下文 this.refreshContext(context); // 启动后的一些处理，留给用户扩展使用，目前这个方法里面是空的 this.afterRefresh(context, applicationArguments); // 结束计时器 stopWatch.stop(); if (this.logStartupInfo) { (new StartupInfoLogger(this.mainApplicationClass)).logStarted(this.getApplicationLog(), stopWatch); } // 发布上下文准备就绪事件 listeners.started(context); this.callRunners(context, applicationArguments); } catch (Throwable var10) { this.handleRunFailure(context, var10, listeners); throw new IllegalStateException(var10); } try { listeners.running(context); return context; } catch (Throwable var9) { this.handleRunFailure(context, var9, (SpringApplicationRunListeners)null); throw new IllegalStateException(var9); } }
