Zipkin-1.19.0学习系列6：applyInitializers(context);

源码如下：

/**
	 * Apply any {@link ApplicationContextInitializer}s to the context before it is
	 * refreshed.
	 * @param context the configured ApplicationContext (not refreshed yet)
	 * @see ConfigurableApplicationContext#refresh()
	 */
	@SuppressWarnings({ "rawtypes", "unchecked" })
	protected void applyInitializers(ConfigurableApplicationContext context) {
		for (ApplicationContextInitializer initializer : getInitializers()) {
			Class<?> requiredType = GenericTypeResolver.resolveTypeArgument(
					initializer.getClass(), ApplicationContextInitializer.class);
			Assert.isInstanceOf(requiredType, context, "Unable to call initializer.");
			initializer.initialize(context);
		}
	}

debug结果如下：

main[1] print getInitializers()
 getInitializers() = "[
org.springframework.boot.context.config.DelegatingApplicationContextInitializer@c446b14, 
org.springframework.boot.context.ContextIdApplicationContextInitializer@3af356f, 
org.springframework.boot.context.ConfigurationWarningsApplicationContextInitializer@4443ef6f, 
org.springframework.boot.context.web.ServerPortInfoApplicationContextInitializer@7e46d648, 
org.springframework.boot.autoconfigure.SharedMetadataReaderFactoryContextInitializer@51751e5f, 
org.springframework.boot.autoconfigure.logging.AutoConfigurationReportLoggingInitializer@2b0b4d53
]"

下面一个一个分析：

1)DelegatingApplicationContextInitializer

Step completed: "thread=main", org.springframework.boot.context.config.DelegatingApplicationContextInitializer.initialize(), line=54 bci=7
54    		List<Class<?>> initializerClasses = getInitializerClasses(environment);

main[1] next
> 
Step completed: "thread=main", org.springframework.boot.context.config.DelegatingApplicationContextInitializer.initialize(), line=55 bci=13
55    		if (!initializerClasses.isEmpty()) {

main[1] print initializerClasses
 initializerClasses = "[]"
main[1] next
> 
Step completed: "thread=main", org.springframework.boot.context.config.DelegatingApplicationContextInitializer.initialize(), line=58 bci=28
58    	}

什么都不做

2)ContextIdApplicationContextInitializer
 

@Override
	public void initialize(ConfigurableApplicationContext applicationContext) {
		applicationContext.setId(getApplicationId(applicationContext.getEnvironment()));
	}

119    		return name;

main[1] print name
 name = "zipkin-server:shared:9411"
main[1] step
> 
Step completed: "thread=main", org.springframework.boot.context.ContextIdApplicationContextInitializer.initialize(), line=105 bci=11
105    		applicationContext.setId(getApplicationId(applicationContext.getEnvironment()));

main[1] stepsdf
Unrecognized command: 'stepsdf'.  Try help...
main[1] print 		applicationContext
 		applicationContext = "org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext@38f2e97e: startup date [Thu Jan 01 08:00:00 CST 1970]; root of context hierarchy"

3)ConfigurationWarningsApplicationContextInitializer

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

4)ServerPortInfoApplicationContextInitializer

@Override
	public void initialize(ConfigurableApplicationContext applicationContext) {
		applicationContext.addApplicationListener(
				new ApplicationListener<EmbeddedServletContainerInitializedEvent>() {

					@Override
					public void onApplicationEvent(
							EmbeddedServletContainerInitializedEvent event) {
						ServerPortInfoApplicationContextInitializer.this
								.onApplicationEvent(event);
					}

				});
	}

增加一个监听器

5)SharedMetadataReaderFactoryContextInitializer

略

6)AutoConfigurationReportLoggingInitializer

主要是设置自动配置的Bean