SpringBoot 的启动流程

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
5. 调用run方法–> (new SpringApplication(primarySources)).run(args);
6. 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。
7. SpringApplicationListener.starting()
8. 创建一个Spring容器
9. 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()

/**
     * 生成SpringApplication对象
     *      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)
     *      从spring.factories 中获取BootstrapRegistryInitializer对象
     *      initializers = 从spring.factories中获取ApplicationContextInitializer对象
     *      listeners = 从spring.factories中获取ApplicationListener对象
     *
     * 该方法启动SpringBoot项目
     *      调用run方法--> (new SpringApplication(primarySources)).run(args);
     *      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。
     *      SpringApplicationListener.starting()
     *      创建一个Spring容器
     *      ApplicationContextInitializer--->初始化Spring容器
     *      SpringApplicationRunListener.contextPrepared()
     *      把传给run方法的的配置类注册成bean
     *      SpringApplicationRunListener.contextLoaded()
     *      会解析配置类、扫描、启动                               Tomcat/Jetty/Undertow(AutoConfigurationImportSelector、DeferredImportSelector)
     *      SpringApplicationRunListener.started()
     *      callRunners-->ApplicationRunner、CommandLineRunner
     *      SpringApplicationListener.ready()
     *
     */publicSpringApplication(ResourceLoader resourceLoader,Class<?>... primarySources){this.sources =newLinkedHashSet();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 =newLinkedHashSet(Arrays.asList(primarySources));//判断SpringBoot项目类型 webApplicationType=NODE、Servlet、Reactivethis.webApplicationType =WebApplicationType.deduceFromClasspath();//启动应用初始化器this.bootstrapRegistryInitializers =newArrayList(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();}publicConfigurableApplicationContextrun(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 =newDefaultApplicationArguments(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beanBanner 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){(newStartupInfoLogger(this.mainApplicationClass)).logStarted(this.getApplicationLog(), timeTakenToStartup);}
            listeners.started(context, timeTakenToStartup);//执行监听器//callRunners-->ApplicationRunner、CommandLineRunnerthis.callRunners(context, applicationArguments);}catch(Throwable var12){//处理异常this.handleRunFailure(context, var12, listeners);thrownewIllegalStateException(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);thrownewIllegalStateException(var11);}}