Properties Object

Spring Boot supports mapping properties into an object, to have better control over existing configuration.

Automatic Mapping

In this case it will map all the values starting with "db." into any matching field.

@Validated
@ConfigurationProperties(prefix = "db")
public class DatabaseProperties
{

   @NotEmpty
   private String url;

   public final String getUrl()
   {
      return url;
   }

}

Value Injection

In some cases it won't me possible, mostly when the properties structure isn't clean, and then the values will have to be injected.

@Validated
@ConfigurationProperties
public class DatabaseProperties
{

   @NotEmpty
   @Value("${db.url}")
   private String url;

   @NotEmpty
   @Value("${username.db}")
   private String username;

   public final String getUrl()
   {
      return url;
   }

   public final String getUsername()
   {
      return username;
   }

}

Registering and Using

These files can be registered into any configuration class.

@Configuration
@EnableConfigurationProperties(DatabaseProperties.class)
public class ConfigurationClass

And then the properties class can be injected as a dependency.

@Bean
public DataSource datasource(DatabaseProperties dbProperties)