springboot启动流程

https://blog.csdn.net/woshilijiuyi/article/details/82219585

工程请参考 springboot-simple.zip

entry

Application entry is SpringApplication.run(App.class, args);.

• return new SpringApplication(new Class[] {App.class}).run(args);

  • new SpringApplication(new Class[] {App.class})

        this.resourceLoader = resourceLoader;
        Assert.notNull(primarySources, "PrimarySources must not be null");
        this.primarySources = new LinkedHashSet<>(Arrays.asList(primarySources));
        this.webApplicationType = WebApplicationType.deduceFromClasspath();
        setInitializers((Collection) getSpringFactoriesInstances(ApplicationContextInitializer.class));
        setListeners((Collection) getSpringFactoriesInstances(ApplicationListener.class));
        this.mainApplicationClass = deduceMainApplicationClass();
    

    spring.factories:

    • in spring-boot-2.1.6.RELEASE.jar!\META-INF\spring.factories
    • in spring-boot-autoconfigure-2.1.6.RELEASE.jar!/META-INF/spring.factories
      ```text
      SpringFactoriesLoader.loadFactoryNames(ApplicationContextInitializer.class, classLoader):
      names = {LinkedHashSet@1002} size = 6
      0 = "org.springframework.boot.context.ConfigurationWarningsApplicationContextInitializer"
      1 = "org.springframework.boot.context.ContextIdApplicationContextInitializer"
      2 = "org.springframework.boot.context.config.DelegatingApplicationContextInitializer"
      3 = "org.springframework.boot.web.context.ServerPortInfoApplicationContextInitializer"
      4 = "org.springframework.boot.autoconfigure.SharedMetadataReaderFactoryContextInitializer"
      5 = "org.springframework.boot.autoconfigure.logging.ConditionEvaluationReportLoggingListener"

    SpringFactoriesLoader.loadFactoryNames(ApplicationListener.class, classLoader):
    names = {LinkedHashSet@1118} size = 10
    0 = "org.springframework.boot.ClearCachesApplicationListener"
    1 = "org.springframework.boot.builder.ParentContextCloserApplicationListener"
    2 = "org.springframework.boot.context.FileEncodingApplicationListener"
    3 = "org.springframework.boot.context.config.AnsiOutputApplicationListener"
    4 = "org.springframework.boot.context.config.ConfigFileApplicationListener"
    5 = "org.springframework.boot.context.config.DelegatingApplicationListener"
    6 = "org.springframework.boot.context.logging.ClasspathLoggingApplicationListener"
    7 = "org.springframework.boot.context.logging.LoggingApplicationListener"
    8 = "org.springframework.boot.liquibase.LiquibaseServiceLocatorApplicationListener"
    9 = "org.springframework.boot.autoconfigure.BackgroundPreinitializer"

    
    基于如上，可自行创建META-INF\spring.factories文件，并配置自己的ApplicationContextInitializer和ApplicationListener。
    ```text
    org.springframework.context.ApplicationContextInitializer=\
    com.example.SimpleApplicationContextInitializer
    
    org.springframework.context.ApplicationListener=\
    com.example.SimpleApplicationListener
    

  • ConfigurableApplicationContext run(String... args)

    • SpringApplicationRunListeners listeners = getRunListeners(args);

       names = {LinkedHashSet@1299}  size = 1
        0 = "org.springframework.boot.context.event.EventPublishingRunListener"
      

    • listeners.starting(); --> ApplicationStartingEvent
    • listeners.environmentPrepared(environment); --> ApplicationEnvironmentPreparedEvent
    • --> ApplicationStartedEvent