org.apache.deltaspike.core.spi.config.ConfigSource Maven / Gradle / Ivy
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*
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package org.apache.deltaspike.core.spi.config;
import java.util.Map;
/**
* Implement this interfaces to provide a ConfigSource.
* A ConfigSource provides properties from a specific place, like
* JNDI configuration, a properties file, etc
*
* The custom implementation can be 'registered' using a
* {@link ConfigSourceProvider} or via the
* {@link java.util.ServiceLoader} mechanism. In the later case
* it must get registered via creating a
* META-INF/services/org.apache.deltaspike.core.spi.config.ConfigSource
* file and adding the fully qualified class name of your ConfigSource
* implementation into it.
*/
public interface ConfigSource
{
/**
* The default name for the ordinal field.
* Any ConfigSource might use it's own though or even return a hardcoded
* in {@link #getOrdinal()}.
*/
String DELTASPIKE_ORDINAL = "deltaspike_ordinal";
/**
* Lookup order:
*
*
* - System properties (ordinal 400)
* - Environment properties (ordinal 300)
* - JNDI values (ordinal 200)
* - Properties file values (/META-INF/apache-deltaspike.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
*
*
*
* IMPORTANT: Have a look at the abstract base-implementation DeltaSpike is using internally,
* if a custom implementation should load the ordinal value from the config-source like the default
* implementations provided by DeltaSpike do.
*
*
*
* 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.
*
* @return the 'importance' aka ordinal of the configured values. The higher, the more important.
*/
int getOrdinal();
/**
* Return properties contained in this config source.
* @return Properties available in this config source.
*/
Map getProperties();
/**
* @param key for the property
* @return configured value or null
if this ConfigSource doesn't provide any value for the given key.
*/
String getPropertyValue(String key);
/**
* @return the 'name' of the configuration source, e.g. 'property-file mylocation/myproperty.properties'
*/
String getConfigName();
/**
* Determines if this config source should be scanned for its list of properties.
*
* Generally, slow ConfigSources should return false here.
*
* @return true if this ConfigSource should be scanned for its list of properties,
* false if it should not be scanned.
*/
boolean isScannable();
}