Springboot启动类
@SpringBootApplication public class TestApplication { public static void main(String[] args) { SpringApplication.run(TestApplication.class, args); } }
SpringBootApplication注解
@Target(ElementType.TYPE) @Retention(RetentionPolicy.RUNTIME) @Documented @Inherited @SpringBootConfiguration @EnableAutoConfiguration @ComponentScan(excludeFilters = { @Filter(type = FilterType.CUSTOM, classes = TypeExcludeFilter.class), @Filter(type = FilterType.CUSTOM, classes = AutoConfigurationExcludeFilter.class) }) public @interface SpringBootApplication {
@SpringBootApplication注解上标注了@EnableAutoConfiguration,表示TestApplication是引导类。
Springboot的启动方法中传入了两个参数,引导类,和程序参数。
public static ConfigurableApplicationContext run(Class> primarySource, String... args) { return run(new Class>[] { primarySource }, args); }
调用run方法
public static ConfigurableApplicationContext run(Class>[] primarySources, String[] args) { return new SpringApplication(primarySources).run(args); }
run方法中有两步,创建SpringApplication和执行SpringApplication的run方法。
1、创建SpringApplication
SpringApplication的构造器
public SpringApplication(Class>... primarySources) { this(null, primarySources); }
private ResourceLoader resourceLoader; private Set> primarySources; public SpringApplication(ResourceLoader resourceLoader, Class>... primarySources) { //将resourceLoader赋值成员变量,此处是null this.resourceLoader = resourceLoader; Assert.notNull(primarySources, "PrimarySources must not be null"); //将引导类赋值成员变量 this.primarySources = new LinkedHashSet<>(Arrays.asList(primarySources)); //判断web类型,赋值成员变量 this.webApplicationType = WebApplicationType.deduceFromClasspath(); //加载初始化器 setInitializers((Collection) getSpringFactoriesInstances(ApplicationContextInitializer.class)); //加载监听器 setListeners((Collection) getSpringFactoriesInstances(ApplicationListener.class)); //获得引导类 this.mainApplicationClass = deduceMainApplicationClass(); }
1.1、判断web类型
//org.springframework.boot.WebApplicationType#deduceFromClasspath static WebApplicationType deduceFromClasspath() { //WEBFLUX_INDICATOR_CLASS = "org.springframework.web.reactive.DispatcherHandler"; //JERSEY_INDICATOR_CLASS = "org.glassfish.jersey.servlet.ServletContainer"; if (ClassUtils.isPresent(WEBFLUX_INDICATOR_CLASS, null) && !ClassUtils.isPresent(WEBMVC_INDICATOR_CLASS, null) && !ClassUtils.isPresent(JERSEY_INDICATOR_CLASS, null)) { return WebApplicationType.REACTIVE; } //SERVLET_INDICATOR_CLASSES = { "javax.servlet.Servlet", "org.springframework.web.context.ConfigurableWebApplicationContext" } for (String className : SERVLET_INDICATOR_CLASSES) { if (!ClassUtils.isPresent(className, null)) { return WebApplicationType.NONE; } } return WebApplicationType.SERVLET; }
1.2、加载上下文初始化器
利用spi加载 ApplicationContextInitializer 的实现类
privateCollection getSpringFactoriesInstances(Class type) { return getSpringFactoriesInstances(type, new Class>[] {}); }
privateCollection getSpringFactoriesInstances(Class type, Class>[] parameterTypes, Object... args) { //获取classloader ClassLoader classLoader = getClassLoader(); // Use names and ensure unique to protect against duplicates //获取配置文件中接口实现类的全限定名 Set names = new LinkedHashSet<>(SpringFactoriesLoader.loadFactoryNames(type, classLoader)); //初始化 List instances = createSpringFactoriesInstances(type, parameterTypes, classLoader, args, names); AnnotationAwareOrderComparator.sort(instances); //返回 return instances; }
public ClassLoader getClassLoader() { if (this.resourceLoader != null) { return this.resourceLoader.getClassLoader(); } return ClassUtils.getDefaultClassLoader(); }
privateList createSpringFactoriesInstances(Class type, Class>[] parameterTypes, ClassLoader classLoader, Object[] args, Set names) { List instances = new ArrayList<>(names.size()); for (String name : names) { try { Class> instanceClass = ClassUtils.forName(name, classLoader); Assert.isAssignable(type, instanceClass); Constructor> constructor = instanceClass.getDeclaredConstructor(parameterTypes); T instance = (T) BeanUtils.instantiateClass(constructor, args); instances.add(instance); } catch (Throwable ex) { throw new IllegalArgumentException("Cannot instantiate " + type + " : " + name, ex); } } return instances; }
将初始化好的上下文初始化器设置到成员变量
//private List> initializers; public void setInitializers(Collection extends ApplicationContextInitializer>> initializers) { this.initializers = new ArrayList<>(initializers); }
1.3、加载监听器
将初始化好的监听器设置到成员变量
//private List> listeners; public void setListeners(Collection extends ApplicationListener>> listeners) { this.listeners = new ArrayList<>(listeners); }
1.4、获得引导类类型
private Class> deduceMainApplicationClass() { try { StackTraceElement[] stackTrace = new RuntimeException().getStackTrace(); for (StackTraceElement stackTraceElement : stackTrace) { //获取main方法的类 if ("main".equals(stackTraceElement.getMethodName())) { return Class.forName(stackTraceElement.getClassName()); } } } catch (ClassNotFoundException ex) { // Swallow and continue } return null; }
2、执行SpringApplication的run方法启动Springboot
public ConfigurableApplicationContext run(String... args) { //启动停止监听器 StopWatch stopWatch = new StopWatch(); stopWatch.start(); //Spring上下文 ConfigurableApplicationContext context = null; //错误导出 CollectionexceptionReporters = new ArrayList<>(); configureHeadlessProperty(); //运行时监听器 SpringApplicationRunListeners listeners = getRunListeners(args); //启动运行时监听器 listeners.starting(); try { //生成ApplicationArguments ApplicationArguments applicationArguments = new DefaultApplicationArguments(args); //准备environment ConfigurableEnvironment environment = prepareEnvironment(listeners, applicationArguments); configureIgnoreBeanInfo(environment); //打印banner Banner printedBanner = printBanner(environment); //创建Spring上下文 context = createApplicationContext(); exceptionReporters = getSpringFactoriesInstances(SpringBootExceptionReporter.class, new Class[] { ConfigurableApplicationContext.class }, context); //准备上下文 prepareContext(context, environment, listeners, applicationArguments, printedBanner); //刷新上下文 refreshContext(context); //上下文刷新后 afterRefresh(context, applicationArguments); //停止 停止监听器 stopWatch.stop(); if (this.logStartupInfo) { new StartupInfoLogger(this.mainApplicationClass).logStarted(getApplicationLog(), stopWatch); } //停止运行时监听器 listeners.started(context); //执行回调 callRunners(context, applicationArguments); } catch (Throwable ex) { handleRunFailure(context, ex, exceptionReporters, listeners); throw new IllegalStateException(ex); } try { listeners.running(context); } catch (Throwable ex) { handleRunFailure(context, ex, exceptionReporters, null); throw new IllegalStateException(ex); } return context; }
2.1、准备environment
private ConfigurableEnvironment prepareEnvironment(SpringApplicationRunListeners listeners, ApplicationArguments applicationArguments) { // Create and configure the environment //创建environment ConfigurableEnvironment environment = getOrCreateEnvironment(); //配置environment configureEnvironment(environment, applicationArguments.getSourceArgs()); ConfigurationPropertySources.attach(environment); listeners.environmentPrepared(environment); bindToSpringApplication(environment); if (!this.isCustomEnvironment) { environment = new EnvironmentConverter(getClassLoader()).convertEnvironmentIfNecessary(environment, deduceEnvironmentClass()); } ConfigurationPropertySources.attach(environment); return environment; }
2.1.1、创建environment
private ConfigurableEnvironment getOrCreateEnvironment() { if (this.environment != null) { return this.environment; } switch (this.webApplicationType) { case SERVLET: return new StandardServletEnvironment(); case REACTIVE: return new StandardReactiveWebEnvironment(); default: return new StandardEnvironment(); } }
这里根据web类型创建不同的environment
2.1.2、配置environment
protected void configureEnvironment(ConfigurableEnvironment environment, String[] args) { if (this.addConversionService) { //转换服务 ConversionService conversionService = ApplicationConversionService.getSharedInstance(); environment.setConversionService((ConfigurableConversionService) conversionService); } configurePropertySources(environment, args); configureProfiles(environment, args); }
配置PropertySources
protected void configurePropertySources(ConfigurableEnvironment environment, String[] args) { MutablePropertySources sources = environment.getPropertySources(); if (this.defaultProperties != null && !this.defaultProperties.isEmpty()) { sources.addLast(new MapPropertySource("defaultProperties", this.defaultProperties)); } if (this.addCommandLineProperties && args.length > 0) { String name = CommandLinePropertySource.COMMAND_LINE_PROPERTY_SOURCE_NAME; if (sources.contains(name)) { PropertySource> source = sources.get(name); CompositePropertySource composite = new CompositePropertySource(name); composite.addPropertySource( new SimpleCommandLinePropertySource("springApplicationCommandLineArgs", args)); composite.addPropertySource(source); sources.replace(name, composite); } else { sources.addFirst(new SimpleCommandLinePropertySource(args)); } } }
主要为了在PropertySources添加一个SimpleCommandLinePropertySource。
配置profiles
protected void configureProfiles(ConfigurableEnvironment environment, String[] args) { Setprofiles = new LinkedHashSet<>(this.additionalProfiles); profiles.addAll(Arrays.asList(environment.getActiveProfiles())); environment.setActiveProfiles(StringUtils.toStringArray(profiles)); }
将profile添加到environment
2.2、打印Banner
private Banner.Mode bannerMode = Banner.Mode.CONSOLE; private Banner printBanner(ConfigurableEnvironment environment) { //无需打印 if (this.bannerMode == Banner.Mode.OFF) { return null; } ResourceLoader resourceLoader = (this.resourceLoader != null) ? this.resourceLoader : new DefaultResourceLoader(getClassLoader()); SpringApplicationBannerPrinter bannerPrinter = new SpringApplicationBannerPrinter(resourceLoader, this.banner); if (this.bannerMode == Mode.LOG) { return bannerPrinter.print(environment, this.mainApplicationClass, logger); } return bannerPrinter.print(environment, this.mainApplicationClass, System.out); }
2.3、创建Spring上下文
//DEFAULT_SERVLET_WEB_CONTEXT_CLASS = "org.springframework.boot." //+"web.servlet.context.AnnotationConfigServletWebServerApplicationContext"; //DEFAULT_REACTIVE_WEB_CONTEXT_CLASS = "org.springframework." //+"boot.web.reactive.context.AnnotationConfigReactiveWebServerApplicationContext"; //DEFAULT_CONTEXT_CLASS = "org.springframework.context." // + "annotation.AnnotationConfigApplicationContext"; protected ConfigurableApplicationContext createApplicationContext() { Class> contextClass = this.applicationContextClass; if (contextClass == null) { try { switch (this.webApplicationType) { case SERVLET: contextClass = Class.forName(DEFAULT_SERVLET_WEB_CONTEXT_CLASS); break; case REACTIVE: contextClass = Class.forName(DEFAULT_REACTIVE_WEB_CONTEXT_CLASS); break; default: contextClass = Class.forName(DEFAULT_CONTEXT_CLASS); } } catch (ClassNotFoundException ex) { throw new IllegalStateException( "Unable create a default ApplicationContext, please specify an ApplicationContextClass", ex); } } //初始化上下文并返回 return (ConfigurableApplicationContext) BeanUtils.instantiateClass(contextClass); }
2.4、准备上下文
private void prepareContext(ConfigurableApplicationContext context, ConfigurableEnvironment environment, SpringApplicationRunListeners listeners, ApplicationArguments applicationArguments, Banner printedBanner) { context.setEnvironment(environment); //ApplicationContext的后置处理 postProcessApplicationContext(context); //应用初始化器 applyInitializers(context); //运行时监听器的准备上下文监听 listeners.contextPrepared(context); if (this.logStartupInfo) { logStartupInfo(context.getParent() == null); logStartupProfileInfo(context); } // Add boot specific singleton beans //获取beanFactory ConfigurableListableBeanFactory beanFactory = context.getBeanFactory(); //将程序入参注册bean springApplicationArguments beanFactory.registerSingleton("springApplicationArguments", applicationArguments); //将banner注册bean springBootBanner if (printedBanner != null) { beanFactory.registerSingleton("springBootBanner", printedBanner); } //设置BeanDefinition是否允许重写 if (beanFactory instanceof DefaultListableBeanFactory) { ((DefaultListableBeanFactory) beanFactory) .setAllowBeanDefinitionOverriding(this.allowBeanDefinitionOverriding); } //初始化允许懒加载,设置BeanfactorypostProcessor if (this.lazyInitialization) { context.addBeanFactoryPostProcessor(new LazyInitializationBeanFactoryPostProcessor()); } // Load the sources //获取source Set
2.4.1、ApplicationContext的后置处理
protected void postProcessApplicationContext(ConfigurableApplicationContext context) { //注册 beanNameGenerator if (this.beanNameGenerator != null) { context.getBeanFactory().registerSingleton(AnnotationConfigUtils.CONFIGURATION_BEAN_NAME_GENERATOR, this.beanNameGenerator); } //注册 resourceLoader if (this.resourceLoader != null) { if (context instanceof GenericApplicationContext) { ((GenericApplicationContext) context).setResourceLoader(this.resourceLoader); } if (context instanceof DefaultResourceLoader) { ((DefaultResourceLoader) context).setClassLoader(this.resourceLoader.getClassLoader()); } } //设置 ConversionService if (this.addConversionService) { context.getBeanFactory().setConversionService(ApplicationConversionService.getSharedInstance()); } }
//org.springframework.boot.convert.ApplicationConversionService#getSharedInstance public static ConversionService getSharedInstance() { ApplicationConversionService sharedInstance = ApplicationConversionService.sharedInstance; if (sharedInstance == null) { synchronized (ApplicationConversionService.class) { sharedInstance = ApplicationConversionService.sharedInstance; if (sharedInstance == null) { sharedInstance = new ApplicationConversionService(); ApplicationConversionService.sharedInstance = sharedInstance; } } } return sharedInstance; }
2.4.2、应用初始化器
protected void applyInitializers(ConfigurableApplicationContext context) { for (ApplicationContextInitializer initializer : getInitializers()) { Class> requiredType = GenericTypeResolver.resolveTypeArgument(initializer.getClass(), ApplicationContextInitializer.class); Assert.isInstanceOf(requiredType, context, "Unable to call initializer."); initializer.initialize(context); } }
执行所有实现了 ApplicationContextInitializer 接口的类的initialize方法。
2.4.3、获取sources
public Set
这里组装了引导类和自定义的source
2.4.4、加载
protected void load(ApplicationContext context, Object[] sources) { if (logger.isDebugEnabled()) { logger.debug("Loading source " + StringUtils.arrayToCommaDelimitedString(sources)); } //创建BeanDefinitionLoader BeanDefinitionLoader loader = createBeanDefinitionLoader(getBeanDefinitionRegistry(context), sources); if (this.beanNameGenerator != null) { loader.setBeanNameGenerator(this.beanNameGenerator); } if (this.resourceLoader != null) { loader.setResourceLoader(this.resourceLoader); } if (this.environment != null) { loader.setEnvironment(this.environment); } //加载,spring的逻辑,这里会将引导类注册 loader.load(); }
protected BeanDefinitionLoader createBeanDefinitionLoader(BeanDefinitionRegistry registry, Object[] sources) { return new BeanDefinitionLoader(registry, sources); }
2.5、刷新上下文
private void refreshContext(ConfigurableApplicationContext context) { refresh(context); if (this.registerShutdownHook) { try { //注册钩子 关闭SpringBoot容器 context.registerShutdownHook(); } catch (AccessControlException ex) { // Not allowed in some environments. } } }
刷新
protected void refresh(ApplicationContext applicationContext) { Assert.isInstanceOf(AbstractApplicationContext.class, applicationContext); //执行spring容器的刷新 ((AbstractApplicationContext) applicationContext).refresh(); }
2.6、上下文刷新后
protected void afterRefresh(ConfigurableApplicationContext context, ApplicationArguments args) { }
这里是一个空实现,应该是作为模板扩展吧。
2.7、执行回调
private void callRunners(ApplicationContext context, ApplicationArguments args) { Listrunners = new ArrayList<>(); runners.addAll(context.getBeansOfType(ApplicationRunner.class).values()); runners.addAll(context.getBeansOfType(CommandLineRunner.class).values()); AnnotationAwareOrderComparator.sort(runners); for (Object runner : new LinkedHashSet<>(runners)) { if (runner instanceof ApplicationRunner) { callRunner((ApplicationRunner) runner, args); } if (runner instanceof CommandLineRunner) { callRunner((CommandLineRunner) runner, args); } } }
这里会调用所有实现了ApplicationRunner,CommandLineRunner的接口的实现类的run方法。
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