org.apache.tamaya.spi

Interface PropertySource

public interface PropertySource

This interface models a provider that serves configuration properties. The contained properties may be read fromMap single or several sources (composite).
PropertySources are the building blocks of the final configuration.

Implementation Requirements

Implementations current this interface must be

• Thread safe.

A PropertySourceProvider will get picked up via the ServiceLoader mechanism and can be registered via META-INF/services/org.apache.tamaya.spi.PropertySource

If you like to register multiple PropertySources at the same time you can use the PropertySourceProvider interface.

Field Summary

Fields

Modifier and Type	Field and Description
static String	TAMAYA_ORDINAL property name to override default tamaya ordinals

Method Summary

Modifier and Type	Method and Description
default String	get(String key) Access a property.
default int	getDefaultOrdinal() Returns the default ordinal used, when no ordinal is set, or the ordinal was not parseable to an int value.
String	getName() Get the name of the property source.
default int	getOrdinal() Lookup order: TODO rethink whole default PropertySources and ordering: TODO introduce default values or constants for ordinals System properties (ordinal 400) Environment properties (ordinal 300) JNDI values (ordinal 200) Properties file values (/META-INF/applicationConfiguration.properties) (ordinal 100) Important Hints for custom implementations: If a custom implementation should be invoked before the default implementations, use a value > 400 If a custom implementation should be invoked after the default implementations, use a value < 100 Reordering of the default order of the config-sources: Example: If the properties file/s should be used before the other implementations, you have to configure an ordinal > 400.
Map<String,String>	getProperties() Access the current properties as Map.
default boolean	isScannable() Determines if this config source could be scanned for its list of properties.

Field Detail

TAMAYA_ORDINAL

static final String TAMAYA_ORDINAL

property name to override default tamaya ordinals

See Also:

Constant Field Values

Method Detail

getOrdinal

default int getOrdinal()

Lookup order: TODO rethink whole default PropertySources and ordering: TODO introduce default values or constants for ordinals

1. System properties (ordinal 400)
2. Environment properties (ordinal 300)
3. JNDI values (ordinal 200)
4. Properties file values (/META-INF/applicationConfiguration.properties) (ordinal 100)

Important Hints for custom implementations:

If a custom implementation should be invoked before the default implementations, use a value > 400

If a custom implementation should be invoked after the default implementations, use a value < 100

Reordering of the default order of the config-sources:

Example: If the properties file/s should be used before the other implementations, you have to configure an ordinal > 400. That means, you have to add e.g. deltaspike_ordinal=401 to /META-INF/apache-deltaspike.properties . Hint: In case of property files every file is handled as independent config-source, but all of them have ordinal 400 by default (and can be reordered in a fine-grained manner.

Returns:

the 'importance' aka ordinal of the configured values. The higher, the more important.

getDefaultOrdinal

default int getDefaultOrdinal()

Returns the default ordinal used, when no ordinal is set, or the ordinal was not parseable to an int value.

Returns:

the default ordinal used, by default 0.

getName

String getName()

Get the name of the property source. The name should be unique for the type of source, whereas multiple instances of the same type (and thus name) may exist in a system. Give a ConfigurationContext the name of a PropertySource is unique.

Returns:

the property source's name, never null.

get

default String get(String key)

Access a property.

//X TODO discuss if the key can be null

Parameters:

key - the property's key, not null.

Returns:

the value assigned to the property or null. An empty String will kind of 'erase' previous values.

getProperties

Map<String,String> getProperties()

Access the current properties as Map. The resulting Map may not return all items accessible, e.g. when the underlying storage does not support iteration of its entries.

Returns:

the a corresponding map, never null. //X TODO or should we just do getPropertyKeys()? Think about security (key) vs easier merging (full map)?

isScannable

default boolean isScannable()

Determines if this config source could be scanned for its list of properties.

PropertySources which are not scannable might not be able to find all the configured values to provide via getProperties(). This can e.g. happen if the underlying storage doesn't support listing.

Returns:

true if this PropertySource could be scanned for its list of properties, false if it should not be scanned.