在 SpringBoot 中读取环境变量

2022-01-16 00:00:00 environment-variables spring java spring-boot

在 SpringBoot 中读取环境变量的最佳方法是什么?
在 Java 中，我使用:

What is the best way to read environment variables in SpringBoot?
In Java I did it using:

String foo = System.getenv("bar");

是否可以使用 @Value 注释来做到这一点?

Is it possible to do it using @Value annotation?

推荐答案

引用 文档:

Spring Boot 允许您将配置外部化，以便您可以在不同的环境中使用相同的应用程序代码.您可以使用属性文件、YAML 文件、环境变量和命令行参数来外部化配置.属性值可以使用 @Value 注释 直接注入到您的 bean 中，通过 Spring 的 Environment 抽象访问或通过 绑定到结构化对象@ConfigurationProperties.

Spring Boot allows you to externalize your configuration so you can work with the same application code in different environments. You can use properties files, YAML files, environment variables and command-line arguments to externalize configuration. Property values can be injected directly into your beans using the @Value annotation, accessed via Spring’s Environment abstraction or bound to structured objects via @ConfigurationProperties.

所以，既然 Spring boot 允许你使用环境变量进行配置，而且 Spring boot 也允许你使用 @Value 从配置中读取一个属性，那么答案是肯定的.

So, since Spring boot allows you to use environment variables for configuration, and since Spring boot also allows you to use @Value to read a property from the configuration, the answer is yes.

例如，以下将给出相同的结果:

For example, the following will give the same result:

@Component
public class TestRunner implements CommandLineRunner {
    @Value("${bar}")
    private String bar;
    private final Logger logger = LoggerFactory.getLogger(getClass());
    @Override
    public void run(String... strings) throws Exception {
        logger.info("Foo from @Value: {}", bar);
        logger.info("Foo from System.getenv(): {}", System.getenv("bar")); // Same output as line above
    }
}

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