Package org.eclipse.microprofile.config

Interface Config

  • @ProviderType
public interface Config
    Resolves the property value by searching through all configured ConfigSources. If the same property is specified in multiple ConfigSources, the value in the ConfigSource with the highest ordinal will be used.

    If multiple ConfigSources are specified with the same ordinal, the ConfigSource.getName() will be used for sorting.

    The config objects produced via the injection model @Inject Config are guaranteed to be serializable, while the programmatically created ones are not required to be serializable.

    If one or more converters are registered for a class of a requested value then the registered Converter which has the highest @jakarta.annotation.Priority is used to convert the string value retrieved from the config sources.

    Usage

    For accessing the config you can use the ConfigProvider: 

     public void doSomething() {
     Config cfg = ConfigProvider.getConfig();
     String archiveUrl = cfg.getValue("my.project.archive.endpoint", String.class);
     Integer archivePort = cfg.getValue("my.project.archive.port", Integer.class);
 }

    It is also possible to inject the Config if a DI container is available: 

     public class MyService {
     @Inject
     private Config config;
 }

    See getValue(String, Class) and getOptionalValue(String, Class) for accessing a configured value.

    Configured values can also be accessed via injection. See ConfigProperty for more information.

    Author:
    Mark Struberg, Gerhard Petracek, Ron Smeral, Emily Jiang, Gunnar Morling

    • Field Detail

      • PROPERTY_EXPRESSIONS_ENABLED

        static final String PROPERTY_EXPRESSIONS_ENABLED
        The value of the property determines whether the property expression is enabled or disabled. The value false means the property expression is disabled, while true means enabled. By default, the value is set to true.
        See Also:
        Constant Field Values

    • Method Detail

      • getValue

        <T> T getValue​(String propertyName,
               Class<T> propertyType)
        Return the resolved property value with the specified type for the specified property name from the underlying configuration sources.

        The configuration value is not guaranteed to be cached by the implementation, and may be expensive to compute; therefore, if the returned value is intended to be frequently used, callers should consider storing rather than recomputing it.

        The result of this method is identical to the result of calling getOptionalValue(propertyName, propertyType).get(). In particular, If the given property name or the value element of this property does not exist, the NoSuchElementException is thrown. This method never returns null.

        Type Parameters:
        T - The property type
        Parameters:
        propertyName - The configuration property name
        propertyType - The type into which the resolved property value should get converted
        Returns:
        the resolved property value as an instance of the requested type (not null)
        Throws:
        IllegalArgumentException - if the property cannot be converted to the specified type
        NoSuchElementException - if the property is not defined or is defined as an empty string or the converter returns null

      • getConfigValue

        ConfigValue getConfigValue​(String propertyName)
        Return the ConfigValue for the specified property name from the underlying configuration source. The lookup of the configuration is performed immediately, meaning that calls to ConfigValue will always yield the same results.

        The configuration value is not guaranteed to be cached by the implementation, and may be expensive to compute; therefore, if the returned value is intended to be frequently used, callers should consider storing rather than recomputing it.

        A ConfigValue is always returned even if a property name cannot be found. In this case, every method in ConfigValue returns null except for ConfigValue.getName(), which includes the original property name being looked up.

        Parameters:
        propertyName - The configuration property name
        Returns:
        the resolved property value as a ConfigValue

      • getValues

        default <T> List<T> getValues​(String propertyName,
                              Class<T> propertyType)
        Return the resolved property values with the specified type for the specified property name from the underlying configuration sources.

        The configuration values are not guaranteed to be cached by the implementation, and may be expensive to compute; therefore, if the returned values are intended to be frequently used, callers should consider storing rather than recomputing them.

        Type Parameters:
        T - The property type
        Parameters:
        propertyName - The configuration property name
        propertyType - The type into which the resolved property values should get converted
        Returns:
        the resolved property values as a list of instances of the requested type
        Throws:
        IllegalArgumentException - if the property values cannot be converted to the specified type
        NoSuchElementException - if the property isn't present in the configuration or is defined as an empty string or the converter returns null

      • getOptionalValue

        <T> Optional<T> getOptionalValue​(String propertyName,
                                 Class<T> propertyType)
        Return the resolved property value with the specified type for the specified property name from the underlying configuration sources.

        The configuration value is not guaranteed to be cached by the implementation, and may be expensive to compute; therefore, if the returned value is intended to be frequently used, callers should consider storing rather than recomputing it.

        If this method is used very often then consider to locally store the configured value.

        Type Parameters:
        T - The property type
        Parameters:
        propertyName - The configuration property name
        propertyType - The type into which the resolved property value should be converted
        Returns:
        The resolved property value as an Optional wrapping the requested type
        Throws:
        IllegalArgumentException - if the property cannot be converted to the specified type

      • getOptionalValues

        default <T> Optional<List<T>> getOptionalValues​(String propertyName,
                                                Class<T> propertyType)
        Return the resolved property values with the specified type for the specified property name from the underlying configuration sources.

        The configuration values are not guaranteed to be cached by the implementation, and may be expensive to compute; therefore, if the returned values are intended to be frequently used, callers should consider storing rather than recomputing them.

        Type Parameters:
        T - The property type
        Parameters:
        propertyName - The configuration property name
        propertyType - The type into which the resolved property values should be converted
        Returns:
        The resolved property values as an Optional wrapping a list of the requested type
        Throws:
        IllegalArgumentException - if the property cannot be converted to the specified type

      • getPropertyNames

        Iterable<String> getPropertyNames()
        Returns a sequence of configuration property names. The order of the returned property names is unspecified.

        The returned property names are unique; that is, if a name is returned once by a given iteration, it will not be returned again during that same iteration.

        There is no guarantee about the completeness or currency of the names returned, nor is there any guarantee that a name that is returned by the iterator will resolve to a non-empty value or be found in any configuration source associated with the configuration; for example, it is allowed for this method to return an empty set always. However, the implementation should return a set of names that is useful to a user that wishes to browse the configuration.

        It is implementation-defined whether the returned names reflect a point-in-time "snapshot" of names, or an aggregation of multiple point-in-time "snapshots", or a more dynamic view of the available property names. Implementations are not required to return the same sequence of names on each iteration; however, the produced Iterator must adhere to the contract of that class, and must not return any more elements once its hasNext() method returns false.

        The returned instance is thread safe and may be iterated concurrently. The individual iterators are not thread-safe.

        Returns:
        the names of all configured keys of the underlying configuration

      • getConfigSources

        Iterable<ConfigSource> getConfigSources()
        Return all of the currently registered configuration sources for this configuration.

        The returned sources will be sorted by descending ordinal value and name, which can be iterated in a thread-safe manner. The Iterable contains a fixed number of configuration sources, determined at application start time, and the config sources themselves may be static or dynamic.

        Returns:
        the configuration sources

      • getConverter

        <T> Optional<Converter<T>> getConverter​(Class<T> forType)
        Return the Converter used by this instance to produce instances of the specified type from string values.
        Type Parameters:
        T - the conversion type
        Parameters:
        forType - the type to be produced by the converter
        Returns:
        an Optional containing the converter, or empty if no converter is available for the specified type

      • unwrap

        <T> T unwrap​(Class<T> type)
        Returns an instance of the specific class, to allow access to the provider specific API.

        If the MP Config provider implementation does not support the specified class, a IllegalArgumentException is thrown.

        Unwrapping to the provider specific API may lead to non-portable behaviour.

        Type Parameters:
        T - The type to unwrap to
        Parameters:
        type - Class representing the type to unwrap to
        Returns:
        An instance of the given type
        Throws:
        IllegalArgumentException - If the current provider does not support unwrapping to the given type