Spring-是否可以在属性文件中递归解析属性（例如环境变量）？

Question

I am using @PropertySource and PropertySourcesPlaceholderConfigurer to load my properties file:

@Configuration
@PropertySource("classpath:app.properties")
class MyApp {
    @Bean
    public PropertySourcesPlaceholderConfigurer PropertySourcesPlaceholderConfigurer() {
        return new PropertySourcesPlaceholderConfigurer();
    }
}

In app.properties , I would like to have:

database.dataSource.url=jdbc:postgresql://localhost:${db-port:5432}/mydb

Here, the port of the database is either resolved from the property db-port , or defaulted to 5432.

This would allow me to spawn my application with the -Ddb-port=9876 flag if necessary. If this flag is not set, the default port as written in app.properties should be taken.

Answer 1

根据https://docs.spring.io/spring-boot/docs/current/reference/html/boot-features-external-config.html和https://stackoverflow.com/a/41779883/ 4785937