spring boot实战(第六篇)加载application资源文件源码分析

本文链接：https://blog.youkuaiyun.com/liaokailin/article/details/48878447

本文深入探讨Spring Boot的ConfigFileApplicationListener，解析PropertiesPropertySourceLoader和YamlPropertySourceLoader如何处理.properties和.yml配置文件。通过时序图展示加载过程，诚邀您关注并支持。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

前言

在上一篇中了解了spring配置资源的加载过程，本篇在此基础上学习spring boot如何默认加载application.xml等文件信息的。

ConfigFileApplicationListener

在 spring boot实战(第三篇)事件监听源码分析中可知在构造SpringApplication时加载相关的监听器，其中存在一个监听器ConfigFileApplicationListener，其定义如下：

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

监听 ApplicationEvent 事件，在触发所有其子类以及本身事件时会执行其onApplicationEvent方法。在执行

			for (SpringApplicationRunListener runListener : runListeners) {
				runListener.environmentPrepared(environment);
			}

时会触发到

if (event instanceof ApplicationEnvironmentPreparedEvent) {
			onApplicationEnvironmentPreparedEvent((ApplicationEnvironmentPreparedEvent) event);
		}

中；

private void onApplicationEnvironmentPreparedEvent(
			ApplicationEnvironmentPreparedEvent event) {
		Environment environment = event.getEnvironment();
		if (environment instanceof ConfigurableEnvironment) {
			onApplicationEnvironmentPreparedEvent((ConfigurableEnvironment) environment,
					event.getSpringApplication());
		}
	}

在上一篇中可以知道enviroment为StandardServletEnvironment实例，因此执行 onApplicationEnvironmentPreparedEvent 方法

private void onApplicationEnvironmentPreparedEvent(
			ConfigurableEnvironment environment, SpringApplication application) {
		addPropertySources(environment, application.getResourceLoader());
		bindToSpringApplication(environment, application);
	}

首先来看 addPropertySources 相关信息

protected void addPropertySources(ConfigurableEnvironment environment,
			ResourceLoader resourceLoader) {
		RandomValuePropertySource.addToEnvironment(environment);
		try {
			new Loader(environment, resourceLoader).load();
		}
		catch (IOException ex)