# 74.3 改变应用程序外部配置文件的位置

默认情况下，来自不同源的属性以一个定义好的顺序添加到Spring的`Environment`中（精确顺序可查看'Sprin Boot特性'章节的[24.外部化配置](https://docs.spring.io/spring-boot/docs/2.0.0.RELEASE/reference/htmlsingle/#boot-features-external-config)）。

为应用程序源添加`@PropertySource`注解是一种很好的添加和修改源顺序的方法。传递给`SpringApplication`静态便利设施（convenience）方法的类和使用`setSources()`添加的类都会被检查，以查看它们是否有`@PropertySources`，如果有，这些属性会被尽可能早的添加到`Environment`里，以确保`ApplicationContext`生命周期的所有阶段都能使用。以这种方式添加的属性优先级低于任何使用默认位置（比如`application.properties`）添加的属性，系统属性，环境变量或命令行参数。

你也可以提供系统属性（或环境变量）来改变该行为：

* `spring.config.name`（`SPRING_CONFIG_NAME`）是根文件名，默认为`application`。
* `spring.config.location`（`SPRING_CONFIG_LOCATION`）是要加载的文件（例如，一个classpath资源或URL）。Spring Boot为该文档设置一个单独的`Environment`属性，它可以被系统属性，环境变量或命令行参数覆盖。

不管你在environment设置什么，Spring Boot都将加载上面讨论过的`application.properties`。如果使用YAML，那具有`.yml`扩展的文件默认也会被添加到该列表，详情参考[ConfigFileApplicationListener](https://github.com/spring-projects/spring-boot/tree/v2.0.0.RELEASE/spring-boot-project/spring-boot/src/main/java/org/springframework/boot/context/config/ConfigFileApplicationListener.java)


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