springboot源码流程解析

springboot 2.3.0

1.启动流程

span style=\"font-size: inherit;\

this.resourceLoader = resourceLoader;

this.primarySources = new LinkedHashSet<>(Arrays.asList(primarySources)); 

this.webApplicationType = WebApplicationType.deduceFromClasspath(); 

REACTIVE

NONE

SERVLET

setInitializers((Collection) getSpringFactoriesInstances(ApplicationContextInitializer.class)); 

getSpringFactoriesInstances(ApplicationContextInitializer.class，new Class<?>[] {})

getClassLoader()

(List)loadSpringFactories(classLoader)

setInitializers--this.initializers = new ArrayList<>(initializers)

setListeners((Collection) getSpringFactoriesInstances(ApplicationListener.class)); --this.listeners = new ArrayList<>(listeners);

this.mainApplicationClass = deduceMainApplicationClass(); 

#run(args)

ConfigurableApplicationContext context = null

Collection<SpringBootExceptionReporter> exceptionReporters = new ArrayList<>()

SpringApplicationRunListeners listeners = getRunListeners(args);

listeners.starting()

RestartApplicationListener#onApplicationStartingEvent

ApplicationArguments applicationArguments = new DefaultApplicationArguments(args)

configureIgnoreBeanInfo(environment);

Banner printedBanner = printBanner(environment);

context = createApplicationContext();

若没有显示指定容器的类型，则根据this.webApplicationType创建class

若为SERVLET，创建AnnotationConfigServletWebServerApplicationContext，反射实例化

context.setEnvironment(environment)

postProcessApplicationContext(context); 

applyInitializers(context);

循环依次initializer.initialize(context)

listeners.contextPrepared(context);

beanFactory.registerSingleton(\"springApplicationArguments\

若this.lazyInitialization：默认false，可在yaml配置main:lazy-initialization:truecontext.addBeanFactoryPostProcessor(new LazyInitializationBeanFactoryPostProcessor())

Set<Object> sources = getAllSources();

listeners.contextLoaded(context);

refreshContext(context);

refresh((ApplicationContext) context);

大部分与普通springioc容器流程相同，详情见springioc流程分析

不同点

#invokeBeanFactoryPostProcessors

ServletWebServerApplicationContext#Onfresh

this.themeSource = UiApplicationContextUtils.initThemeSource(this);

createWebServer()

ServletWebServerFactory factory = getWebServerFactory();

this.webServer = factory.getWebServer(getSelfInitializer());

getSelfInitializer()--return this::selfInitialize: 传入方法引用，匿名函数，在之后webServer初始化时调用>>>>selfInitialize(ServletContext servletContext)

prepareWebApplicationContext(servletContext);

Object rootContext = servletContext.getAttribute(WebApplicationContext.ROOT_WEB_APPLICATION_CONTEXT_ATTRIBUTE);

setServletContext(servletContext);

registerApplicationScope(servletContext);

ServletContextScope appScope = new ServletContextScope(servletContext);

for (ServletContextInitializer beans : getServletContextInitializerBeans())>>beans.onStartup(servletContext);

getServletContextInitializerBeans()--return new ServletContextInitializerBeans(getBeanFactory());----addServletContextInitializerBeans(beanFactory);----addAdaptableBeans(beanFactory);

getWebServer(ServletContextInitializer... initializers)

Tomcat tomcat = new Tomcat();

TomcatEmbeddedContext context = new TomcatEmbeddedContext();

addDefaultServlet(context);

TomcatStarter starter = new TomcatStarter(initializers);

for (TomcatContextCustomizer customizer : this.tomcatContextCustomizers) {    customizer.customize(context);\t\t}

postProcessContext(context);

getBeanFactory().registerSingleton(\"webServerGracefulShutdown\

getBeanFactory().registerSingleton(\"webServerStartStop\

sources.replace(\"servletContextInitParams\

sources.replace(\"servletConfigInitParams\

#registerListeners

详情见springioc流程分析

#finishRefresh

getLifecycleProcessor().onRefresh();

DefaultLifecycleProcessor#startBeans(true);

webServerStartStop#start

this.webServer.start();

this.running = true;

webServerGracefulShutdown

根据各个bean不同的应用阶段分组

调用LifecycleGroup中的所有Lifecycle的start方法

this.webServer.start()

context.registerShutdownHook();

listeners.started(context);

List<Object> runners = new ArrayList<>();

runners.addAll(context.getBeansOfType(ApplicationRunner.class).values());

runners.addAll(context.getBeansOfType(CommandLineRunner.class).values());

listeners.running(context);

2.@SpringBootApplication

@SpringBootConfiguration

@Configuration

@Component

说明Spring的配置类也是Spring的一个组件

AutoConfigurationExcludeFilter

 TypeExcludeFilter

@EnableAutoConfiguration

@AutoConfigurationPackage

@Import(AutoConfigurationPackages.Registrar.class)自动注册包---主配置类所在的包:com.kuang.demo包

#registerBeanDefinitions

@Import(AutoConfigurationImportSelector.class)自动导入包的核心

#selectImports(AnnotationMetadata annotationMetadata)

#isEnabled(AnnotationMetadata metadata)

#getAutoConfigurationEntry(AnnotationMetadata annotationMetadata)

导入的类：自动导入选择器AutoConfigurationImportSelector

类里有个方法：getAutoConfigurationEntry作用：获得自动配置实体

该方法里调用了方法：getCandidateConfigurations目的：获取候选的配置

getSpringFactoriesLoaderFactoryClass()return EnableAutoConfiguration.class;获取标注了EnableAutoConfiguration这个注解的类：包括主启动类public class Application

应用

自定义运行监听器

implements SpringApplicationRunListenerextends EventPublishingRunListener

写入factories中

插手ServletContext初始化工作

implements ServletContextInitializer

自定义配置嵌入式Servlet容器

implements WebServerFactoryCustomizer<TomcatServletWebServerFactory>

mvc自定义配置

implements WebMvcConfigurer

自定义事件

extends ApplicationEvent

ApplicationContext.publishEvent(“”)

自定义事件监听器

容器事件

implements ApplicationListener<ApplicationEvent>

implements GenericApplicationListener

要想从容器创建开始就监听所有事件，在spring.factories配置key=org.springframework.context.ApplicationListener

请求事件

extends RequestContextListener

插手容器启动时提供参数

implements ApplicationRunner

implements CommandLineRunner

3.ApplicationContextInitializer（系统初始化器

1.ApplicationContextInitializer 介绍

新建一个类 MyApplicationContextInitializer 并实现 ApplicationContextInitializer 接口

SpringBoot的main方法application.addInitializers

application.properties配置

SpringBoot的SPI扩展---META-INF/spring.factories中配置

4.监听器Listenter

SpringBoot框架事件

图片

获取监听器列表

触发机制

自定监听器

5.Bean的创建

6.Banner解析

7.计时器

StopWatch用来统计任务的耗时

8.启动类加载器

9.Spring Boot starter介绍以及自定义starter

1.starter介绍

2.自定义starter

pom文件添加spring-boot-autoconfigure和spring-boot-configuration-processor

创建PriceAutoConfiguration。增加注解EnableConfigurationProperties， ConditionalOnProperty

spring.factories中添加自动配置类实现

3.源码解析

我们引入starter的依赖，会将自动配置的类的jar引入。@SpringBootApplication的注解中有一个是@EnableAutoConfiguration注解，这个注解有一个@Import({EnableAutoConfigurationImportSelector.class})，EnableAutoConfigurationImportSelector内部则是使用了SpringFactoriesLoader.loadFactoryNames方法进行扫描具有META-INF/spring.factories文件的jar包。 启动类上@SpringBootApplication - 引入AutoConfigurationImportSelector - ConfigurationClassParser 中处理 - 获取spring.factories中EnableAutoConfiguration实现

原理

4.webflux解析

WebFlux请求处理流程