Configuration

When the library is used without any additional configuration a configuration suitable for standalone applications is applied by default.

File based configuration

As a preferred alternative, configuration file based method is provided: Add a dev.orne.i18n.config.properties file in the class path resources with the configuration options.

# If context should be thread exclusive or shared among threads. Allows SHARED, THREAD. Defaults to THREAD.
dev.orne.i18n.context.provider=THREAD
# If context is inherited by child threads in per-thread context providers. Defaults to true.
dev.orne.i18n.context.inherited=true
# The default application language. Defaults to Locale.getDefault().
dev.orne.i18n.language.default=en
# The languages supported by the application. Optional, not used internally. Defaults to Locale.getAvailableLocales().
dev.orne.i18n.language.available=bn,en,es,hi,zh
# The default I18N resources bundle. Defaults to "messages".
dev.orne.i18n.resources=messages
# Additional alternative named I18N resources bundles. Optional. In this example exposed as "errors".
dev.orne.i18n.resources.named.errors=error-messages

The configuration file takes effect for the class loader that provides it and all child class loaders that don't provide a new configuration file. This is specially usefull for J2EE evironments, where different WARS packed in a single EAR can provide different configurations while other threads using the EAR's class loader (executors threads, for example) use the shared EAR-level configuration.

Multiple configuration files in a single class loader are not allowed and throw an exception.

Support for custom context providers can be added registering implementations of dev.orne.i18n.context.I18nContextProviderFactory through Java SPI.

Programmatic configuration

To change the I18N configuration or context provider programmatically a class implementing the interface I18nContextProvider.Configurer can call setI18nConfiguration() to override the configuration or setI18nContextProvider() to set a fully configured context provider instance:

class I18nConfigurer implements I18nContextProvider.Configurer {

    void configureI18n() {
        // Set configuration (do not use 'dev.orne.i18n.config.properties' file)
        setI18nConfiguration(config);

        // and/or

        // Configure context provider
        I18nContextProvider provider = ...;
        // Register for this thread and child threads
        setI18nContextProvider(provider);
    }
}

Spring configuration

In Spring based applications just add EnableI18N annotation to Spring context configuration. This anotation will link de I18N context to Spring LocaleContextHolder, use application's default MessageSource as default I18N resources source and, if spring-web is in the classpath, register a listener of Spring's RequestHandledEvent events to clear I18N context between HTTP requests.

@Configuration
@EnableI18N
class SpringConfig {
    // Application beans configuration
}

On applications with Spring contexts hierarchies property classLoader can be set to provide a class of the class loader being configured. This allows I18N configuration EAR wide,

@Configuration
@EnableI18N(classLoader = EarSpringConfig.class)
class EarSpringConfig {
    // Configures shared I18N provider for all WARs and EJBs
}

@Configuration
@EnableI18N
class War1SpringConfig {
    // Configures custom I18N configuration for this WAR
}

@Configuration
class War2SpringConfig {
    // Uses shared I18N provider
}

Additional configuration can be applied implementing the I18nSpringConfigurer interface. For example, to extract context configuation from application provided properties:

@Configuration
@EnableI18N
class SpringConfig implements I18nSpringConfigurer {

    @Bean
    public Properties applicationConfiguration() {
        ...
    }

    @Override
    public void configureI18nContextProvider(
            @NotNull I18nSpringContextProvider.Builder builder) {
        // Default implementation
        builder.configure(applicationConfiguration());
    }
}