Injecting properties into the Spring environment

Besides the separation of environment-specific configuration using profiles, you would still need to externalize many properties, such as database URLs, e-mails, and date formats in a property file for easier handling. These properties would then either be injected directly into the beans or read from environment by the beans at runtime. Spring's environment abstraction, together with @PropertySource annotation, makes this possible in Spring applications.

The @PropertySource annotation provides a convenient and declarative mechanism for adding a PropertySource to Spring's environment:

@Configuration
@PropertySource("classpath:application.properties")
@ComponentScan(basePackages = "com.springessentialsbook")
public class SpringJavaConfigurator {
...
   @Autowired
   @Lazy
   private SystemSettings systemSettings;

   @Autowired
   private Environment env;

   @Bean
   public SystemSettings getSystemSettings() {
      String dateFormat = env.getProperty("system.date-format");
      String appDisplayName = env.getProperty("app.displayname");

      return new SystemSettings(dateFormat, appDisplayName);
   }
…
}