Package io.helidon.config

Interface ConfigMapper<T>

Type Parameters:

T - Java type to which the ConfigMapper converts Config subtree.

Functional Interface:

This is a functional interface and can therefore be used as the assignment target for a lambda expression or method reference.

@FunctionalInterface
public interface ConfigMapper<T>

Contextual mapper of a configuration hierarchy to a Java type.

The application can register mappers on a Builder using the Config.Builder.addMapper(Class, ConfigMapper) method. The config system also locates mappers using the ConfigMapperProvider SPI that it discovers using the Java ServiceLoader mechanism and automatically adds them to every Builder unless the application disables this feature for a given Builder by invoking Config.Builder.disableMapperServices().

See Also:

Config.Builder.addMapper(Class, ConfigMapper), Config.Builder.addMapper(Class, java.util.function.Function), Config.Builder.addMapper(io.helidon.config.spi.ConfigMapperProvider), Config.as(Class), Config.as(Class, Object), Config.asOptional(Class), Config.asList(Class), Config.asList(Class, java.util.List), Config.asOptionalList(Class), Config.map(ConfigMapper), Config.map(ConfigMapper, Object), Config.mapOptional(ConfigMapper), Config.mapList(ConfigMapper), Config.mapList(ConfigMapper, java.util.List), Config.mapOptionalList(ConfigMapper), ConfigMappers, ConfigMapperProvider, Config.Value

Method Summary

Modifier and Type	Method and Description
T	apply(Config config) Maps a configuration hierarchy to a Java representation.

Method Detail

apply

T apply(Config config)
 throws ConfigMappingException,
        MissingValueException

Maps a configuration hierarchy to a Java representation.

Parameters:

config - configuration node representing a configuration tree to be mapped to an instance of a Java type.

Returns:

node mapped to a given java type.

Throws:

MissingValueException - in case the configuration tree does not contain all expected sub-nodes required by the mapper implementation to provide instance of Java type.

ConfigMappingException - in case the mapper fails to map the (existing) configuration tree represented by the supplied configuration node to an instance of a given Java type.