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Spring Boot ApplicationListener ? ApplicationContextInitializer ??

? Spring Boot ??????ApplicationListener ? ApplicationContextInitializer ????????????????????????????? Spring Boot ??????

???????????

ApplicationListener ??????? Spring ?? IOC ???????????????????????????????????????????????

package com.roy.applicationContextInitializer;
import org.springframework.context.ApplicationContextInitializer;
import org.springframework.context.ConfigurableApplicationContext;
public class MyApplicationContextInitializer implements ApplicationContextInitializer {
    @Override
    public void initialize(ConfigurableApplicationContext context) {
        System.out.println("==== systemProperties ===========");
        context.getEnvironment().getSystemProperties().forEach((key, value) -> {
            System.out.println(key + "===" + value);
        });
        System.out.println("==== systemProperties end ===========");
    }
}

?????????? Spring Boot ??????

@SpringBootApplication
public class P1Application implements CommandLineRunner {
    public static void main(String[] args) {
        final SpringApplication application = new SpringApplication(P1Application.class);
        application.addInitializers(new MyApplicationContextInitializer());
        application.run(args);
    }
    @Autowired
    private ApplicationContext applicationContext;
    
    @Override
    public void run(String... args) throws Exception {
        System.out.println("Application ID: " + applicationContext.getId());
    }
}

?????????????????????????

????????

????????????????? Spring Boot ???????????????????????????

public SpringApplication(ResourceLoader resourceLoader, Class
   ... primarySources) {
    this.sources = new LinkedHashSet();
    this.bannerMode = Mode.CONSOLE;
    this.logStartupInfo = true;
    this.addCommandLineProperties = true;
    this.addConversionService = true;
    this.headless = true;
    this.registerShutdownHook = true;
    this.additionalProfiles = Collections.emptySet();
    this.isCustomEnvironment = false;
    this.lazyInitialization = false;
    this.applicationContextFactory = ApplicationContextFactory.DEFAULT;
    this.applicationStartup = ApplicationStartup.DEFAULT;
    this.resourceLoader = resourceLoader;
    Assert.notNull(primarySources, "PrimarySources must not be null");
    this.primarySources = new LinkedHashSet(Arrays.asList(primarySources));
    this.webApplicationType = WebApplicationType.deduceFromClasspath();
    this.bootstrapRegistryInitializers = this.getBootstrapRegistryInitializersFromSpringFactories();
    this.setInitializers(this.getSpringFactoriesInstances(ApplicationContextInitializer.class));
}

??????????Spring Boot ??? SpringApplication ????????? ApplicationContextInitializer ????

??Spring Boot ?????

Spring Boot ?????????????????????????????????????ContextIdApplicationContextInitializer ???? ApplicationContext ? ID?

public class ContextIdApplicationContextInitializer 
    implements ApplicationContextInitializer, Ordered {
    private int order = Ordered.LOWEST_PRECEDENCE - 10;
    @Override
    public void initialize(ConfigurableApplicationContext applicationContext) {
        applicationContext.setId(contextId(applicationContext).getId());
        applicationContext.getBeanFactory().registerSingleton(
            ContextId.class.getName(), contextId(applicationContext));
    }
    private ContextId contextId(ConfigurableApplicationContext applicationContext) {
        ApplicationContext parent = applicationContext.getParent();
        if (parent != null && parent.containsBean(ContextId.class.getName())) {
            return parent.getBean(ContextId.class).createChildId();
        }
        return new ContextId(getApplicationId(applicationContext.getEnvironment()));
    }
    private String getApplicationId(ConfigurableEnvironment environment) {
        String name = environment.getProperty("spring.application.name");
        return StringUtils.hasText(name) ? name : "application";
    }
}

??????????????? spring.application.name ????????? ApplicationContext ? ID?

???????????????????? Spring Boot ??????

????????

? Spring Boot ??????????????????????????????????? Spring Boot ???????????? ApplicationContextInitializer ??????????????????????? Spring Boot ???????????????