springboot 源码笔记

时间：2022-03-03 23:29:59

1.springAppication构造器

　　基于getSpringFactoriesInstances方法构造如下类(获取文件内容在META-INF/spring.factories文件中)

　　1.1 初始化ApplicationContextInitializer.class

# Application Context Initializers

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

　　1.2 初始化ApplicationListener.class

# Application Listeners
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

2.run方法

		StopWatch stopWatch = new StopWatch();//构造时间观察器

		stopWatch.start();// 打印一个开始时间

		ConfigurableApplicationContext context = null;

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

		configureHeadlessProperty();// 配置headless 依据java.awt.headless

		SpringApplicationRunListeners listeners = getRunListeners(args);// 解析如下

		// getSpringFactoriesInstances方法获取SpringApplicationRunListener.class对象->EventPublishingRunListener对象

			// EventPublishingRunListener对象初始化时,构造器内会执行下面的逻辑

				//SimpleApplicationEventMulticaster广播器初始化,并且将listener设置到广播器中

		// 将上面获取到的EventPublishingRunListener对象对象添加到SpringApplicationRunListeners对象中

		listeners.starting(); // 解析如下

		// 调用EventPublishingRunListener对象的starting方法

			// 将ApplicationStartingEvent广播出去 SimpleApplicationEventMulticaster->multicastEvent方法

			// 调用getApplicationListeners方法获取所有listeners,然后循环广播

			// 调用支持事件的listener的listener.onApplicationEvent(event);方法,驱动listener巡行

			// 此处支持的listener如下

				// org.springframework.boot.logging.LoggingApplicationListener,

				// org.springframework.boot.autoconfigure.BackgroundPreinitializer,

				// org.springframework.boot.context.config.DelegatingApplicationListener,

				// org.springframework.boot.liquibase.LiquibaseServiceLocatorApplicationListener

		try {

			ApplicationArguments applicationArguments = new DefaultApplicationArguments(

					args);

			// 创建一个DefaultApplicationArguments对象,构造器中构造了一个新的SOURCE对象

			// 根据SOURCE对象的继承结构->SimpleCommandLinePropertySource->parse方法

				// 如果args是–开头的,就加入OptionArg中,否则加入到NonOptionArg中

			// CommandLinePropertySource构造其中commandLineArgs存入source

			ConfigurableEnvironment environment = prepareEnvironment(listeners,

					applicationArguments);

			// 参照下面的prepareEnvironment方法分析

			configureIgnoreBeanInfo(environment);

			Banner printedBanner = printBanner(environment); // 打印banner

			context = createApplicationContext();

			// 创建applicationContext

			// 添加AnnotationTypeFilter–>Component 添加AnnotationTypeFilter –> ManagedBean 添加AnnotationTypeFilter –> javax.inject.Named

			// 

			exceptionReporters = getSpringFactoriesInstances(

					SpringBootExceptionReporter.class,

					new Class[] { ConfigurableApplicationContext.class }, context);

			// 异常处理

			prepareContext(context, environment, listeners, applicationArguments,

					printedBanner);

			//

			refreshContext(context);

			//

			afterRefresh(context, applicationArguments);

			stopWatch.stop();

			if (this.logStartupInfo) {

				new StartupInfoLogger(this.mainApplicationClass)

						.logStarted(getApplicationLog(), stopWatch);

			}

			listeners.started(context);

			callRunners(context, applicationArguments);

		}

　　

prepareEnvironment方法分析

private ConfigurableEnvironment prepareEnvironment(

			SpringApplicationRunListeners listeners,

			ApplicationArguments applicationArguments) {

		// Create and configure the environment

		ConfigurableEnvironment environment = getOrCreateEnvironment();

		// 获取或者创建ConfigurableEnvironment 构造environment对象 继承AbstractEnvironment

		// AbstractEnvironment构造器中调用customizePropertySources方法

		// StandardEnvironment对象:配置systemEnvironment systemProperties

		// StandardServletEnvironment对象:配置servletContextInitParams servletConfigInitParams jndiProperties

		configureEnvironment(environment, applicationArguments.getSourceArgs());

		// 配置环境的信息

		// configurePropertySources 配置PropertySources

			// commandLineArgs、servletConfigInitParams、servletContextInitParams、jndiProperties（如果存在）、

			// systemProperties、systemEnvironment、defaultProperties（如果存在）

		// configureProfiles 配置Profiles

			// 至于哪个具体的配置文件会被加载，需要在application.properties文件中通过spring.profiles.active属性来设置，其值对应{profile}值。

			//  application-dev.properties：开发环境  application-test.properties：测试环境 application-prod.properties：生产环境

		listeners.environmentPrepared(environment);

		// 通知所有的观察者,发送ApplicationEnvironmentPreparedEvent事件.

			// org.springframework.boot.context.config.ConfigFileApplicationListener,

			// org.springframework.boot.context.config.AnsiOutputApplicationListener,

			// org.springframework.boot.logging.LoggingApplicationListener,

			// org.springframework.boot.logging.ClasspathLoggingApplicationListener,

			// org.springframework.boot.autoconfigure.BackgroundPreinitializer,

			// org.springframework.boot.context.config.DelegatingApplicationListener,

			// org.springframework.boot.context.FileEncodingApplicationListener

		//

		bindToSpringApplication(environment);

		if (!this.isCustomEnvironment) {

			environment = new EnvironmentConverter(getClassLoader())

					.convertEnvironmentIfNecessary(environment, deduceEnvironmentClass());

		}

		ConfigurationPropertySources.attach(environment);

		return environment;

	}

　　

prepareContext分析
private void prepareContext(ConfigurableApplicationContext context,

        ConfigurableEnvironment environment, SpringApplicationRunListeners listeners,

        ApplicationArguments applicationArguments, Banner printedBanner) {

    // 1. 上下文设置环境

    context.setEnvironment(environment);

    // 2. 调用postProcessApplicationContext方法设置上下文的beanNameGenerator和resourceLoader(如果SpringApplication有的话)

    postProcessApplicationContext(context);

    // 3. 拿到之前实例化SpringApplication对象的时候设置的ApplicationContextInitializer，调用它们的initialize方法，对上下文做初始化

    applyInitializers(context);

    // 4. contextPrepareds 是一个空实现

    listeners.contextPrepared(context);

    // 5. 打印启动日志

    if (this.logStartupInfo) {

        logStartupInfo(context.getParent() == null);

        logStartupProfileInfo(context);

    }

    // Add boot specific singleton beans

    // 6. 日志往上下文的beanFactory中注册一个singleton的bean，bean的名字是springApplicationArguments，bean的实例是之前实例化的ApplicationArguments对象

    context.getBeanFactory().registerSingleton("springApplicationArguments",

            applicationArguments);

    // 如果之前获取的printedBanner不为空，那么往上下文的beanFactory中注册一个singleton的bean，bean的名字是springBootBanner，bean的实例就是这个printedBanner

    if (printedBanner != null) {

        context.getBeanFactory().registerSingleton("springBootBanner", printedBanner);

    }

    // Load the sources

    Set<Object> sources = getSources();

    Assert.notEmpty(sources, "Sources must not be empty");

    // 7. 调用load方法注册启动类的bean定义，也就是调用SpringApplication.run(Application.class, args);的类，SpringApplication的load方法内会创建BeanDefinitionLoader的对象，并调用它的load()方法

    load(context, sources.toArray(new Object[sources.size()]));

    // 8. 调用listeners的contextLoaded方法，说明上下文已经加载，该方法先找到所有的ApplicationListener，遍历这些listener，如果该listener继承了ApplicationContextAware类，那么在这一步会调用它的setApplicationContext方法，设置context

    listeners.contextLoaded(context);

}

　　

# Environment Post Processors

org.springframework.boot.env.EnvironmentPostProcessor=\

org.springframework.boot.cloud.CloudFoundryVcapEnvironmentPostProcessor,\

org.springframework.boot.env.SpringApplicationJsonEnvironmentPostProcessor,\

org.springframework.boot.env.SystemEnvironmentPropertySourceEnvironmentPostProcessor

　　

1.SpringFactoriesLoader类

　　loadFactoryNames->loadSpringFactories->META-INF/spring.factories

　　位置:spring-boot-2.0.5.RELEASE-sources.jar目录下

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