Spring Boot 启动过程

阅读源码是最快的学习途径

public static ConfigurableApplicationContext run(Class<?>[] primarySources, String[] args) {
	return new SpringApplication(primarySources).run(args);
}

public SpringApplication(ResourceLoader resourceLoader, Class<?>... primarySources) {
	this.resourceLoader = resourceLoader; // null
	Assert.notNull(primarySources, "PrimarySources must not be null");
	this.primarySources = new LinkedHashSet<>(Arrays.asList(primarySources)); // 带有@SpringBoot的主类
	this.webApplicationType = WebApplicationType.deduceFromClasspath();  //SERVLET
	/**
	通过 SpringFactoriesLoader 从默认资源路径 META-INF/spring.factories 加载
		com.learn.config.MyBootstrapRegistryInitializer
		org.springframework.cloud.bootstrap.RefreshBootstrapRegistryInitializer
		org.springframework.cloud.bootstrap.TextEncryptorConfigBootstrapper
	*/
	this.bootstrapRegistryInitializers = new ArrayList<>(
			getSpringFactoriesInstances(BootstrapRegistryInitializer.class));
	/**
		org.springframework.boot.context.config.DelegatingApplicationContextInitializer@550ee7e5
		org.springframework.boot.autoconfigure.SharedMetadataReaderFactoryContextInitializer@5f9b2141
		org.springframework.boot.context.ContextIdApplicationContextInitializer@247d8ae
		com.learn.config.MyApplicationContextInitializer@48974e45
		org.springframework.boot.context.ConfigurationWarningsApplicationContextInitializer@6a84a97d
		org.springframework.boot.rsocket.context.RSocketPortInfoApplicationContextInitializer@6c130c45
		org.springframework.boot.web.context.ServerPortInfoApplicationContextInitializer@50ad3bc1
		org.springframework.boot.autoconfigure.logging.ConditionEvaluationReportLoggingListener@223aa2f7
	*/
	setInitializers((Collection) getSpringFactoriesInstances(ApplicationContextInitializer.class));
	/**
        org.springframework.cloud.bootstrap.BootstrapApplicationListener@7c711375
		org.springframework.cloud.bootstrap.LoggingSystemShutdownListener@57cf54e1
		org.springframework.boot.env.EnvironmentPostProcessorApplicationListener@5b03b9fe
		org.springframework.boot.context.config.AnsiOutputApplicationListener@37d4349f
		org.springframework.boot.context.logging.LoggingApplicationListener@434a63ab
		org.springframework.boot.autoconfigure.BackgroundPreinitializer@6e0f5f7f
		org.springframework.boot.context.config.DelegatingApplicationListener@2805d709
		org.springframework.cloud.context.restart.RestartListener@3ee37e5a
		org.springframework.boot.builder.ParentContextCloserApplicationListener@2ea41516
		com.learn.config.MyApplicationListener@3a44431a
		org.springframework.boot.ClearCachesApplicationListener@3c7f66c4
		org.springframework.boot.context.FileEncodingApplicationListener@194bcebf
	*/
	setListeners((Collection) getSpringFactoriesInstances(ApplicationListener.class));
	this.mainApplicationClass = deduceMainApplicationClass(); // 找 main 方法
}

• BootstrapRegistryInitializer
  • org.springframework.cloud.bootstrap.RefreshBootstrapRegistryInitializer
  • org.springframework.cloud.bootstrap.TextEncryptorConfigBootstrapper
• ApplicationContextInitializer
  • org.springframework.boot.context.config.DelegatingApplicationContextInitializer@550ee7e5
  • org.springframework.boot.autoconfigure.SharedMetadataReaderFactoryContextInitializer@5f9b2141
  • org.springframework.boot.context.ContextIdApplicationContextInitializer@247d8ae
  • com.learn.config.MyApplicationContextInitializer@48974e45
  • org.springframework.boot.context.ConfigurationWarningsApplicationContextInitializer@6a84a97d
  • org.springframework.boot.rsocket.context.RSocketPortInfoApplicationContextInitializer@6c130c45
  • org.springframework.boot.web.context.ServerPortInfoApplicationContextInitializer@50ad3bc1
  • org.springframework.boot.autoconfigure.logging.ConditionEvaluationReportLoggingListener@223aa2f7
• ApplicationListener
  • org.springframework.cloud.bootstrap.BootstrapApplicationListener@7c711375
    org.springframework.cloud.bootstrap.LoggingSystemShutdownListener@57cf54e1
    org.springframework.boot.env.EnvironmentPostProcessorApplicationListener@5b03b9fe
    org.springframework.boot.context.config.AnsiOutputApplicationListener@37d4349f
    org.springframework.boot.context.logging.LoggingApplicationListener@434a63ab
    org.springframework.boot.autoconfigure.BackgroundPreinitializer@6e0f5f7f
    org.springframework.boot.context.config.DelegatingApplicationListener@2805d709
    org.springframework.cloud.context.restart.RestartListener@3ee37e5a
    org.springframework.boot.builder.ParentContextCloserApplicationListener@2ea41516
    com.learn.config.MyApplicationListener@3a44431a
    org.springframework.boot.ClearCachesApplicationListener@3c7f66c4
    org.springframework.boot.context.FileEncodingApplicationListener@194bcebf
    public class BootstrapApplicationListener implements ApplicationListener, Ordered {}
    监听 EnvironmentPreparedEvent，从 bootstrap 加载配置，取名为 springCloudDefaultProperties，高优先级

    @Override
    public void onApplicationEvent(ApplicationEnvironmentPreparedEvent event) {
    	ConfigurableEnvironment environment = event.getEnvironment();
    	// "spring.cloud.bootstrap.enabled=false" && isNotPresent(org.springframework.cloud.bootstrap.marker.Marker)
    	// && "spring.config.use-legacy-processing=false"
    	if (!bootstrapEnabled(environment) && !useLegacyProcessing(environment)) {
    		return;
    	}
    	// don't listen to events in a bootstrap context 跳过 BootstrapContext，即只处理 ApplicationContext
    	// properties.contains("bootstrap")
    	if (environment.getPropertySources().contains(BOOTSTRAP_PROPERTY_SOURCE_NAME)) {
    		return;
    	}
    	ConfigurableApplicationContext context = null;
    	// 找出 bootstrap 配置
    	String configName = environment.resolvePlaceholders("${spring.cloud.bootstrap.name:bootstrap}");
    	for (ApplicationContextInitializer<?> initializer : event.getSpringApplication().getInitializers()) {
    		if (initializer instanceof ParentContextApplicationContextInitializer) {
    			context = findBootstrapContext((ParentContextApplicationContextInitializer) initializer, configName);
    		}
    	}
    	if (context == null) {
    		context = bootstrapServiceContext(environment, event.getSpringApplication(), configName);
    		event.getSpringApplication().addListeners(new CloseContextOnFailureApplicationListener(context));
    	}
    		
    	apply(context, event.getSpringApplication(), environment);
    }

  • org.springframework.cloud.bootstrap.LoggingSystemShutdownListener@57cf54e
  • org.springframework.boot.env.EnvironmentPostProcessorApplicationListener@
  • org.springframework.boot.context.config.AnsiOutputApplicationListener@37d
  • org.springframework.boot.context.logging.LoggingApplicationListener@434a6
  • org.springframework.boot.autoconfigure.BackgroundPreinitializer@6e0f5f7f
  • org.springframework.boot.context.config.DelegatingApplicationListener@280
  • org.springframework.cloud.context.restart.RestartListener@3ee37e5a
  • org.springframework.boot.builder.ParentContextCloserApplicationListener@2
  • com.learn.config.MyApplicationListener@3a44431a
  • org.springframework.boot.ClearCachesApplicationListener@3c7f66c4
  • org.springframework.boot.context.FileEncodingApplicationListener@194bcebf