# 74.6 设置生效的Spring profiles

Spring `Environment`有一个API可以设置生效的profiles，但通常你会通过系统属性（`spring.profiles.active`）或OS环境变量（`SPRING_PROFILES_ACTIVE`）设置。比如，使用一个`-D`参数启动应用程序（记着把它放到`main`类或jar文件之前）：

```
$ java -jar -Dspring.profiles.active=production demo-0.0.1-SNAPSHOT.jar
```

在Spring Boot中，你也可以在`application.properties`里设置生效的profile，例如：

```java
spring.profiles.active=production
```

通过这种方式设置的值会被系统属性或环境变量替换，但不会被`SpringApplicationBuilder.profiles()`方法替换。因此，后面的Java API可用来在不改变默认设置的情况下增加profiles。

想要获取更多信息可查看'Spring Boot特性'章节的[25. Profiles](https://docs.spring.io/spring-boot/docs/2.0.0.RELEASE/reference/htmlsingle/#boot-features-profiles)。


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