environment与@ConfigurationProperties的关系 加载过程分析

environment是在printBanner之前就初始化好了, 更在context创建之前,

已经加载application-xxxx.properties, System.properties, System.environment ...

也可以自己监听应用启动 SpringApplicationRunListener事件， 完成自己的独特的配置加载方案

启动后调用listener.finished() 打印一些启动后的信息

prepareEnvironment()源码如下

     private ConfigurableEnvironment prepareEnvironment(
             SpringApplicationRunListeners listeners,
             ApplicationArguments applicationArguments) {
         // Create and configure the environment
         ConfigurableEnvironment environment = getOrCreateEnvironment();

 //加载标准目录下的配置文件 &profile
         configureEnvironment(environment, applicationArguments.getSourceArgs());
 //加载自定义的配置方案
         listeners.environmentPrepared(environment);
         if (!this.webEnvironment) {
             environment = new EnvironmentConverter(getClassLoader())
                     .convertToStandardEnvironmentIfNecessary(environment);
         }
         return environment;
     }

@ConfigurationProperties  使用的变量也是从environment中取的

CLI参数配置方式：

参考：

https://docs.spring.io/spring-boot/docs/current/reference/html/boot-features-external-config.html#boot-features-external-config-relaxed-binding

https://www.baeldung.com/properties-with-spring