springboot读取非classpath下配置文件，并且支持注解使用

springboot加载配置文件路径：src下为classpath，src同级目录为file。

@SpringBootApplication
@PropertySource(value = {"file:config/application.yml","file:config/application-dev.yml",
"file:config/application-pro.yml","file:config/application-pro.yml"})
public class Application {
	static {
		System.setProperty("log4j.configurationFile", "file:config/log4j2.xml");
	}
	public static void main(String[] args) {
	    SpringApplicationBuilder builder = new SpringApplicationBuilder();
	    builder.sources(Application.class);//将读取的所有配置载入SpringApplication中
	    builder.build().run(args);
//		SpringApplication.run(Application.class, args);
	}

}

springboot的applition启动时，会扫描配置的包路径下的注解，当注解使用了配置文件中的属性值，那么则要求SpringApplication对象的sources属性必须包含此属性key。

查看SpringApplicationBuilder源码：

 public SpringApplication build(String... args) {
        this.configureAsChildIfNecessary(args);
        this.application.setSources(this.sources);//spring配置文件参数设置给application对象
        return this.application;
 }

另外main函数中可以写成：

SpringApplication.run(Application.class, args);

SpringApplication源码：

    public static ConfigurableApplicationContext run(Object source, String... args) {
        return run(new Object[]{source}, args);
    }

    public static ConfigurableApplicationContext run(Object[] sources, String[] args) {
        return (new SpringApplication(sources)).run(args);
    }

    public static void main(String[] args) throws Exception {
        run(new Object[0], args);
    }