spring boot 配置的加载过程

ConfigFileApplicationListener通过在容器启动的过程中监听相应的事件来加载配置。

public class ConfigFileApplicationListener implements EnvironmentPostProcessor, SmartApplicationListener, Ordered {
    @Override
    public void onApplicationEvent(ApplicationEvent event) {
        if (event instanceof ApplicationEnvironmentPreparedEvent) {
            onApplicationEnvironmentPreparedEvent(
                    (ApplicationEnvironmentPreparedEvent) event);
        }
        if (event instanceof ApplicationPreparedEvent) {
            onApplicationPreparedEvent(event);
        }
    }

    private void onApplicationEnvironmentPreparedEvent(
            ApplicationEnvironmentPreparedEvent event) {
        //从spring.factories中获取所有的EnvironmentPostProcessor
        List<EnvironmentPostProcessor> postProcessors = loadPostProcessors();
        //当前对象也是一个EnvironmentPostProcessor
        postProcessors.add(this);
        //排序
        AnnotationAwareOrderComparator.sort(postProcessors);
        for (EnvironmentPostProcessor postProcessor : postProcessors) {
            //加载配置
            postProcessor.postProcessEnvironment(event.getEnvironment(),
                    event.getSpringApplication());
        }
    }

    /**
    * 当前EnvironmentPostProcessor的处理逻辑
    */
    @Override
    public void postProcessEnvironment(ConfigurableEnvironment environment,
            SpringApplication application) {
        addPropertySources(environment, application.getResourceLoader());
    }

    
    protected void addPropertySources(ConfigurableEnvironment environment,
            ResourceLoader resourceLoader) {
        RandomValuePropertySource.addToEnvironment(environment);
        //new一个loader（在spring.factories文件中找到所有的PropertySourceLoader，如properties,yml文件的Loader[PropertiesPropertySourceLoader，YamlPropertySourceLoader]）并load
        new Loader(environment, resourceLoader).load();
    }
}