flyconf

Lightweight and powerful annotation-based configuration library

Usage Guide:

First of all, you need to create a new FlyconfInstance. FlyconfInstance is a specifically configured container for your configurations. You can use different Flyconf instances if various configurations use different parsers. It allows you to register custom parsers separately.

Creating a new Flyconf instance:
FlyconfInstance instance = Flyconf.newInstance();

FlyconfInstance methods:

• <T> T load(PropertyMapLoader loader, Class<T> into);
• <T> FlyconfInstance registerCustomParser(Class<T> type, Function<String, T> parserFunction);
• FlyconfInstance setDefaultConvention(Convention.ConventionAdapter adapter);
• Convention.ConventionAdapter getConventionAdapter();

Configuration Loading

Let's create a simple .properties configuration interface:

@Configuration
public interface MyConfig {
    String greeting();
}

config.properties:

greeting=Hello World!

File myPropsFile = ...;
MyConfig config = instance.load(new PropertiesConfigurationLoader(myPropsFile), MyConfig.class);
System.out.println(config.greeting());

Output:
Hello World!

Creating advanced configurations

@Configuration
public interface MyAdvancedConfig {
    @Mandatory
    String greeting();
    
    @DefaultValue("Welcome!")
    String title();
    
    Optional<String> subtitle();
    
    @MultiValue(delimiter = "|")
    List<String> description();
    
    @Property("send-message-in")
    Duration sendMessageAfter();
}

Nested configuration sections

@Configuration
public interface JdbcConfig {
    @Mandatory
    String host();
    
    @DefaultValue("3306")
    int port();
    
    String username();
    
    String password();
}

@Configuration
public interface MainConfig {

    String applicationName();
    
    JdbcConfig jdbc();
}

As you can see, our main configuration has a separate JDBC configuration section.

Property Conventions

You can configure your FlyconfInstance or a separate configuration root to adapt Java camelCase convention into any other using ConventionAdapters. There are a few adapters:

• kebab-case implemented by KebabCaseAdapter
• SCREAMING_SNAKE_CASE implemented by ScreamingSnakeCaseAdapter
• snake_case implemented by SnakeCaseAdapter

To set a specific adapter on FlyconfInstance level, use: instance#setDefaultConvention method. You can also set it for specific configuration:

@Configuration
@Convention(adapter = KebabCaseAdapter.class)
public interface MyKebabConfig {
}

Configuration Reloading

Flyconf also provides very easy-to-use reloading mechanism. To make your configuration reloadable, just let it extend Reloadable interface:

@Configuration
public interface MyReloadableConfig extends Reloadable {
}

Then you will be able to call MyReloadableConfig#reload method which automatically reloads all settings from its source (file).