springboot启动源码解析

//构造器初始化
public SpringApplication(ResourceLoader resourceLoader, Class... primarySources) {
this.sources = new LinkedHashSet();
//横幅模式 OFF,CONSOLE,LOG;
this.bannerMode = Mode.CONSOLE;
this.logStartupInfo = true;
this.addCommandLineProperties = true;
this.addConversionService = true;
this.headless = true;
this.registerShutdownHook = true;
this.additionalProfiles = new HashSet();
this.isCustomEnvironment = false;
this.resourceLoader = resourceLoader;
Assert.notNull(primarySources, "PrimarySources must not be null");
this.primarySources = new LinkedHashSet(Arrays.asList(primarySources));
//应用类型NONE,SERVLET,REACTIVE;存在DispatcherHandler，不存在DispatcherServlet，ServletContainer，则为REACTIVE
//不存在javax.servlet.Servlet", "org.springframework.web.context.ConfigurableWebApplicationContext，则为NONE，则为SERVLET
this.webApplicationType = WebApplicationType.deduceFromClasspath();
//spring.factories文件中org.springframework.context.ApplicationContextInitializer= //org.springframework.boot.context.ConfigurationWarningsApplicationContextInitializer, //org.springframework.boot.context.ContextIdApplicationContextInitializer, //org.springframework.boot.context.config.DelegatingApplicationContextInitializer, //org.springframework.boot.web.context.ServerPortInfoApplicationContextInitializer
this.setInitializers(this.getSpringFactoriesInstances(ApplicationContextInitializer.class));
//org.springframework.context.ApplicationListener= //org.springframework.boot.ClearCachesApplicationListener, //org.springframework.boot.builder.ParentContextCloserApplicationListener, //org.springframework.boot.context.FileEncodingApplicationListener, //org.springframework.boot.context.config.AnsiOutputApplicationListener, //org.springframework.boot.context.config.ConfigFileApplicationListener, //org.springframework.boot.context.config.DelegatingApplicationListener, //org.springframework.boot.context.logging.ClasspathLoggingApplicationListener, //org.springframework.boot.context.logging.LoggingApplicationListener, //org.springframework.boot.liquibase.LiquibaseServiceLocatorApplicationListener 进行初始化
this.setListeners(this.getSpringFactoriesInstances(ApplicationListener.class));
//推论出主类main
this.mainApplicationClass = this.deduceMainApplicationClass();
}
//核心开始运行
public ConfigurableApplicationContext run(String... args) {
//秒表，用于记录启动时间，记录每个任务 的时间，
StopWatch stopWatch = new StopWatch();
stopWatch.start();
//spring应用上下文，spring容器
ConfigurableApplicationContext context = null;
//自定义SpringApplication启动错误的回调接口
Collection<SpringBootExceptionReporter> exceptionReporters = new ArrayList();
//java.awt.headless模式 默认为true开启
this.configureHeadlessProperty();
//开启监听
//org.springframework.boot.SpringApplicationRunListener= //org.springframework.boot.context.event.EventPublishingRunListener
SpringApplicationRunListeners listeners = this.getRunListeners(args);
//
listeners.starting();

Collection exceptionReporters;
try {
//参数封装，在命令行下启动应用带的参数，如--server.port
ApplicationArguments applicationArguments = new DefaultApplicationArguments(args);
//环境准备 1.加载外部化配置的资源到environment 2.触发ApplicationEnvironmentPreparedEvent事件
ConfigurableEnvironment environment = this.prepareEnvironment(listeners, applicationArguments);
//配置系统属性spring.beaninfo.ignore
this.configureIgnoreBeanInfo(environment);
//打印横幅
Banner printedBanner = this.printBanner(environment);
//创建ApplicationContext 根据webApplicationType
//SERVLET:
// contextClass = Class.forName("org.springframework.boot.web.servlet.context.AnnotationConfigServletWebServerApplicationContext");
//REACTIVE:
// contextClass = Class.forName("org.springframework.boot.web.reactive.context.AnnotationConfigReactiveWebServerApplicationContext");
// default:
// contextClass = Class.forName("org.springframework.context.annotation.AnnotationConfigApplicationContext");
/**
*AnnotationConfigServletWebServerApplicationContext层级关系-》ServletWebServerApplicationContext-》GenericWebApplicationContext
*-》GenericApplicationContext-》AbstractApplicationContext
*/
//部分属性：reader、scanner、beanFactory进行了实例化
context = this.createApplicationContext();
//实例化 用来支持报告关于启动的错误
//# Error Reporters
//org.springframework.boot.SpringBootExceptionReporter= //org.springframework.boot.diagnostics.FailureAnalyzers
exceptionReporters = this.getSpringFactoriesInstances(SpringBootExceptionReporter.class, new Class[]{ConfigurableApplicationContext.class}, context);
//ApplicationContext准备 加载
this.prepareContext(context, environment, listeners, applicationArguments, printedBanner);
//核心：
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);
}
}
//环境准备
private ConfigurableEnvironment prepareEnvironment(SpringApplicationRunListeners listeners, ApplicationArguments applicationArguments) {
//创建环境 SERVLET StandardServletEnvironment； REACTIVE StandardReactiveWebEnvironment； StandardEnvironment
ConfigurableEnvironment environment = this.getOrCreateEnvironment();
this.configureEnvironment((ConfigurableEnvironment)environment, applicationArguments.getSourceArgs());
listeners.environmentPrepared((ConfigurableEnvironment)environment);
this.bindToSpringApplication((ConfigurableEnvironment)environment);
if (!this.isCustomEnvironment) {
environment = (new EnvironmentConverter(this.getClassLoader())).convertEnvironmentIfNecessary((ConfigurableEnvironment)environment, this.deduceEnvironmentClass());
}

ConfigurationPropertySources.attach((Environment)environment);
return (ConfigurableEnvironment)environment;
}

/**
*AbstractApplicationContext
*/
//刷新
public void refresh() throws BeansException, IllegalStateException {
Object var1 = this.startupShutdownMonitor;
synchronized(this.startupShutdownMonitor) {
//刷新前准备 校验
this.prepareRefresh();
//获取DefaultListableBeanFactory实例
ConfigurableListableBeanFactory beanFactory = this.obtainFreshBeanFactory();
//beanFactory加载配置
this.prepareBeanFactory(beanFactory);

try {
//beanFactory后置处理，重写ApplicationContext的postProcessBeanFactory方法
this.postProcessBeanFactory(beanFactory);
//核心：
this.invokeBeanFactoryPostProcessors(beanFactory);
//注册BeanPostProcessor
this.registerBeanPostProcessors(beanFactory);
this.initMessageSource();
this.initApplicationEventMulticaster();
this.onRefresh();
this.registerListeners();
this.finishBeanFactoryInitialization(beanFactory);
this.finishRefresh();
} catch (BeansException var9) {
if (this.logger.isWarnEnabled()) {
this.logger.warn("Exception encountered during context initialization - cancelling refresh attempt: " + var9);
}

this.destroyBeans();
this.cancelRefresh(var9);
throw var9;
} finally {
this.resetCommonCaches();
}