Spring: what is the programmatic equivalent of @PropertySource

Question

Consider the following setup:

@Configuration
@PropertySource("classpath:common.properties")
public class CommonConfig {

}

Now let's assume that I want some non-trivial logic behind how and what property sources I load in this config, and I want to use the properties API for this:

@Configuration
public class CommonConfig {

    @Autowired
    private ConfigurableEnvironment env;

    public void loadCommonConfig() {
        // Determine what properties to load and how...
        env.getPropertySources().addLast(...);
    }

}

I don't understand how I'm supposed to notify Spring that I am interested in loadCommonConfig to be called in the point in the life cycle where @PropertySource would have been handled. Simply returned the properties as a @Bean did not seem to work.

Answer 1

You must declare a PropertySourcesPlaceholderConfigurer static bean for @PropertySource annotations to work (or use SpringBoot that will declare it for you).

You can manually load properties files when declaring this bean, with method setLocations(...).

Here's an example :

@Configuration
public class CommonConfig {
...
        @Bean
        public static PropertySourcesPlaceholderConfigurer propertyPlaceholderConfigurer() {
            PropertySourcesPlaceholderConfigurer ppc = new PropertySourcesPlaceholderConfigurer();
            ppc.setLocations(new FileSystemResource("/etc/webapp_properties/security-token.properties"),
                    new ClassPathResource("config/WebApp.properties"),
                    new ClassPathResource("config/" + System.getenv("CURRENTENV") + "/WebApp.properties"));
            return ppc;
        }
...
}