SpringBoot 的启动流程
一、 生成SpringApplication对象
1. webApplicationType = 推测web应用的类型(NODE(普通项目)、SERVLET(Servlet web项目)、 * REACTIVE(响应式项目 flux)
2. 从spring.factories 中获取BootstrapRegistryInitializer对象
3. initializers = 从spring.factories中获取ApplicationContextInitializer对象
4. isteners = 从spring.factories中获取ApplicationListener对象
二、 该方法启动SpringBoot项目
1. 调用run方法–> (new SpringApplication(primarySources)).run(args);
2. 先生成SpringApplication对象,之后调用run方法 primarySource --> 传进去的的类相当于配置类,可以为一个数组。
3. SpringApplicationListener.starting()
4. 创建一个Spring容器
5. ApplicationContextInitializer—>初始化Spring容器
6.SpringApplicationRunListener.contextPrepared()
7. 把传给run方法的的配置类注册成bean
8. SpringApplicationRunListener.contextLoaded()会
9. 解析配置类、扫描、启动Tomcat/Jetty/Undertow
(AutoConfigurationImportSelector、DeferredImportSelector)
10. SpringApplicationRunListener.started()
11. callRunners–>ApplicationRunner、CommandLineRunner
12. SpringApplicationListener.ready()
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; //设置applicationContextFactory类型 this.applicationContextFactory = ApplicationContextFactory.DEFAULT; //默认的“无操作”应用程序启动实现 this.applicationStartup = ApplicationStartup.DEFAULT; this.resourceLoader = resourceLoader;//资源 Assert.notNull(primarySources, "PrimarySources must not be null"); //传入的配置类 this.primarySources = new LinkedHashSet(Arrays.asList(primarySources)); //判断SpringBoot项目类型 webApplicationType=NODE、Servlet、Reactive this.webApplicationType = WebApplicationType.deduceFromClasspath(); //启动应用初始化器 this.bootstrapRegistryInitializers = new ArrayList(this.getSpringFactoriesInstances(BootstrapRegistryInitializer.class)); //初始化容器 this.setInitializers(this.getSpringFactoriesInstances(ApplicationContextInitializer.class)); //设置监听器 this.setListeners(this.getSpringFactoriesInstances(ApplicationListener.class)); //检查主应用程序 this.mainApplicationClass = this.deduceMainApplicationClass(); }public ConfigurableApplicationContext run(String... args) { long startTime = System.nanoTime();//记录开始时间 DefaultBootstrapContext bootstrapContext = this.createBootstrapContext(); ConfigurableApplicationContext context = null; this.configureHeadlessProperty(); SpringApplicationRunListeners listeners = this.getRunListeners(args);//获得监听器 listeners.starting(bootstrapContext, this.mainApplicationClass);//执行监听器 try { ApplicationArguments applicationArguments = new DefaultApplicationArguments(args);//初始化默认应用参数类、命令行参数 ConfigurableEnvironment environment = this.prepareEnvironment(listeners, bootstrapContext, applicationArguments);//获得系统环境以及配置信息 this.configureIgnoreBeanInfo(environment);//排除某些bean Banner printedBanner = this.printBanner(environment);//获得打印banner的信息 context = this.createApplicationContext();//创建ApplicationContext即Spring容器 context.setApplicationStartup(this.applicationStartup); this.prepareContext(bootstrapContext, context, environment, listeners, applicationArguments, printedBanner);//SpringApplicationRunListener.contextPrepared() this.refreshContext(context);//刷新应用上下文 this.afterRefresh(context, applicationArguments); Duration timeTakenToStartup = Duration.ofNanos(System.nanoTime() - startTime);//了的获得执行时间 if (this.logStartupInfo) { (new StartupInfoLogger(this.mainApplicationClass)).logStarted(this.getApplicationLog(), timeTakenToStartup); } listeners.started(context, timeTakenToStartup);//执行监听器 //callRunners-->ApplicationRunner、CommandLineRunner this.callRunners(context, applicationArguments); } catch (Throwable var12) { //处理异常 this.handleRunFailure(context, var12, listeners); throw new IllegalStateException(var12); } try { Duration timeTakenToReady = Duration.ofNanos(System.nanoTime() - startTime); //执行ready listeners.ready(context, timeTakenToReady); return context; } catch (Throwable var11) { this.handleRunFailure(context, var11, (SpringApplicationRunListeners)null); throw new IllegalStateException(var11); } }来源地址：https://blog.csdn.net/m0_52058662/article/details/128973271
