springboot ApplicationContextInitializer的三种使用方法小结

 
public class Demo01ApplicationContextInitializer implements ApplicationContextInitializer<ConfigurableApplicationContext> {
    @Override
    public void initialize(ConfigurableApplicationContext configurableApplicationContext) {
        System.out.println("user add method ==> ApplicationContextInitializer");
    }
}

private <T> Collection<? extends T> getSpringFactoriesInstances(Class<T> type,
			Class<?>[] parameterTypes, Object... args) {
		ClassLoader classLoader = Thread.currentThread().getContextClassLoader();
		// Use names and ensure unique to protect against duplicates
		Set<String> names = new LinkedHashSet<String>(
				SpringFactoriesLoader.loadFactoryNames(type, classLoader));
		List<T> instances = createSpringFactoriesInstances(type, parameterTypes,
				classLoader, args, names);
		AnnotationAwareOrderComparator.sort(instances);
		return instances;
	}

private static final String PROPERTY_NAME = "context.initializer.classes";

private List<Class<?>> getInitializerClasses(ConfigurableEnvironment env) {
		String classNames = env.getProperty(PROPERTY_NAME);
		List<Class<?>> classes = new ArrayList<Class<?>>();
		if (StringUtils.hasLength(classNames)) {
			for (String className : StringUtils.tokenizeToStringArray(classNames, ",")) {
				classes.add(getInitializerClass(className));
			}
		}
		return classes;
	}

@SpringBootApplication
public class InitializerDemoApplication { 
	public static void main(String[] args) {
		//type01
		SpringApplication springApplication = new SpringApplication(InitializerDemoApplication.class);
		springApplication.addInitializers(new Demo01ApplicationContextInitializer());
		springApplication.run(args);
 
		//SpringApplication.run(InitializerDemoApplication.class,args);
	}
}

 @Override
 public void initialize(ConfigurableApplicationContext context) {
  ConfigurableEnvironment environment = context.getEnvironment();
  
  List<Class<?>> initializerClasses = getInitializerClasses(environment);
  if (!initializerClasses.isEmpty()) {
   applyInitializerClasses(context, initializerClasses);
  }
 }

 @Override
 public void initialize(ConfigurableApplicationContext applicationContext) {
  
  applicationContext.addBeanFactoryPostProcessor(new CachingMetadataReaderFactoryPostProcessor());
 }

 @Override
 public void initialize(ConfigurableApplicationContext applicationContext) {
  ContextId contextId = getContextId(applicationContext);
  applicationContext.setId(contextId.getId());
  
  applicationContext.getBeanFactory().reGISterSingleton(ContextId.class.getName(), contextId);
 }

 @Override
 public void initialize(ConfigurableApplicationContext context) {
  
  context.addBeanFactoryPostProcessor(new ConfigurationWarningsPostProcessor(getChecks()));
 }

 @Override
 public void initialize(ConfigurableApplicationContext applicationContext) {
   
  applicationContext.addApplicationListener(new Listener(applicationContext));
 }

 @Override
 public void initialize(ConfigurableApplicationContext applicationContext) {
  
  applicationContext.addApplicationListener(this);
 }

 @Override
 public void initialize(ConfigurableApplicationContext applicationContext) {
  this.applicationContext = applicationContext;
  applicationContext.addApplicationListener(new ConditionEvaluationReportListener());
  if (applicationContext instanceof GenericApplicationContext) {
   // Get the report early in case the context fails to load
   // 注册一个监听ApplicationEvent事件的监听器用于打印自动配置后的日志信息
   this.report = ConditionEvaluationReport.get(this.applicationContext.getBeanFactory());
  }
 }