The initial release of smartics Properties has been published! The version tag is 0.1.0, since this is the first release of a project that is based on our smartics Exceptions, but features a bunch of new concepts.

(Do not be confused if the minor number has already changed, since we continuously update the documentation. :-))

This post introduces the basic concepts of this project.

Declaration of Properties

The declaration of properties is modern and much simpler than in the old days. Simply write a Java interface and add the @PropertySet annotation.

@PropertySet("my")
public interface MyProperties {
  String myString();
  URL myUrl();
  List<String> myList();
  MyCustomType myCustomType();
}

With its declaration a property type, constraints and metadata is determined.

Definition of Properties

Providing a value for a declared property is called definition of a property. This can be done in a couple of ways like a simple properties file on the classpath or in a folder on the file system. Or it may be stored in a database or other sort of backend information system.

The definition of the properties declared above in a properties file may look like this:

my.myString=Hello Properties!
my.myUrl=http://www.maycorporation.com/index.html
my.myList=one, two, three
my.myCustomType=purple:123

Please note that the name of the property set (my) is required as a prefix.

Accessing Properties

It is important that the way properties are accessed is independent of how the properties are defined. Therefore an implementation provides a factory that is able to create configurations. A configuration is a set of property sets. Each property set is a collection of properties. While a configuration is specific to an environment and maybe an application within that environment, a property set is not.

It is an implementation detail how a factory is configured to be able to provide configurations to its clients (please refer to the library’s homepage for details – e.g. One-String-Property Tutorial for an implementation that provides access to properties deployed on the classpath).

final ConfigurationPropertiesFactory factory =
    ConfigurationPropertiesFactoryFactory.createDefaultFactory();

final ConfigurationPropertiesManagement config =
    factory.createDefaultManagement();

The code above creates a default configuration.

The following code snippet shows how to access properties:

final MyProperties properties =
  config.getProperties(MyProperties .class);
final String myString = properties.myString();
final URL myUrl = properties.myUrl();
final List<String> myList = properties.myList();
final MyCustomType  myCustomType = properties.myCustomType();

You will find more information on the project’s site, especially on the tutorial pages and the smartics Properties Maven Plugin for integration with Maven.

If you have questions or comments, please do not hesitate to leave a comment or drop us a line!