org.microbean.configuration.spi

Class AbstractResourceLoadingConfiguration<T>

java.lang.Object

org.microbean.configuration.spi.AbstractConfiguration

org.microbean.configuration.spi.AbstractResourceLoadingConfiguration<T>

All Implemented Interfaces:

Configuration, Ranked

Direct Known Subclasses:

PropertiesConfiguration

public abstract class AbstractResourceLoadingConfiguration<T>
extends AbstractConfiguration
implements Ranked

An AbstractConfiguration that flexibly loads some kind of resource, or uses a previously loaded one, to satisfy demands for configuration property values.

Author:

Laird Nelson

See Also:

AbstractResourceLoadingConfiguration(Function), getValue(Resource, Map, String)

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	AbstractResourceLoadingConfiguration.Resource<T> A Supplier of a particular kind of resource from which configuration property values may be retrieved.

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	AbstractResourceLoadingConfiguration(Function<? super Map<? extends String,? extends String>,? extends AbstractResourceLoadingConfiguration.Resource<? extends T>> resourceLoader) Creates a new AbstractResourceLoadingConfiguration.

Method Summary

Modifier and Type	Method and Description
Set<String>	getNames() Returns a Set of the names of all ConfigurationValues that might be returned by this Configuration.
protected abstract Set<String>	getNames(AbstractResourceLoadingConfiguration.Resource<? extends T> resource)
int	getRank()
protected int	getRank(AbstractResourceLoadingConfiguration.Resource<? extends T> resource)
protected abstract ConfigurationValue	getValue(AbstractResourceLoadingConfiguration.Resource<? extends T> resource, Map<String,String> requestedCoordinates, String name) Returns a ConfigurationValue suitable for the supplied name normally sourced in some fashion from the supplied AbstractResourceLoadingConfiguration.Resource, or null if no such ConfigurationValue can be found.
ConfigurationValue	getValue(Map<String,String> coordinates, String name) Returns a ConfigurationValue suitable for the supplied configurationCoordinates and name, or null if there is no suitable value.

Methods inherited from class org.microbean.configuration.spi.AbstractConfiguration

getConfigurations, setConfigurations

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

AbstractResourceLoadingConfiguration

protected AbstractResourceLoadingConfiguration(Function<? super Map<? extends String,? extends String>,? extends AbstractResourceLoadingConfiguration.Resource<? extends T>> resourceLoader)

Creates a new AbstractResourceLoadingConfiguration.

Parameters:

resourceLoader - a Function that accepts a Map of requested configuration coordinates and returns a AbstractResourceLoadingConfiguration.Resource that can supply a source of configuration values for use by the getValue(Resource, Map, String) method; may be null in which case all invocations of the getValue(Map, String) method will return null

See Also:

getValue(Resource, Map, String), getValue(Map, String), AbstractResourceLoadingConfiguration.Resource

Method Detail

getRank

public int getRank()

Specified by:

getRank in interface Ranked

getRank

protected int getRank(AbstractResourceLoadingConfiguration.Resource<? extends T> resource)

getValue

public ConfigurationValue getValue(Map<String,String> coordinates,
                                   String name)

Returns a ConfigurationValue suitable for the supplied configurationCoordinates and name, or null if there is no suitable value.

Implementations of this method may return null.

The ConfigurationValue that is returned must have a name that is equal to the supplied name.

The ConfigurationValue that is returned must be created with this Configuration as the first parameter value supplied to its constructor.

The ConfigurationValue that is returned must be created with a set of configuration coordinates that is a subset of the supplied configurationCoordinates.

This implementation calls the getValue(Resource, Map, String) method with the return value resulting from the invocation of the Function supplied at construction time.

Specified by:

getValue in interface Configuration

Parameters:

coordinates - the requested configuration coordinates; may be null

name - the name of a configuration property for which a value should be returned; must not be null

Returns:

a ConfigurationValue suitable for the supplied configurationCoordinates and name, or null

Throws:

NullPointerException - if name is null

See Also:

getValue(Resource, Map, String)

getNames

public Set<String> getNames()

Description copied from interface: Configuration

Returns a Set of the names of all ConfigurationValues that might be returned by this Configuration.

Implementations of this method must not return null.

Just because a name appears in the returned Set does not mean that a ConfigurationValue will be returned for it in a location in configuration space identified by any arbitrary set of configuration coordinates.

Specified by:

getNames in interface Configuration

Returns:

a non-null Set of names

getValue

protected abstract ConfigurationValue getValue(AbstractResourceLoadingConfiguration.Resource<? extends T> resource,
                                               Map<String,String> requestedCoordinates,
                                               String name)

Returns a ConfigurationValue suitable for the supplied name normally sourced in some fashion from the supplied AbstractResourceLoadingConfiguration.Resource, or null if no such ConfigurationValue can be found.

Implementations of this method are permitted to return null.

Implementations of this method must not call the getValue(Map, String) method or undefined behavior will result.

Parameters:

resource - a AbstractResourceLoadingConfiguration.Resource hopefully providing access to the ultimate source of configuration values for the requested coordinates; must not be null

requestedCoordinates - for convenience, the same Map supplied to the getValue(Map, String) method is supplied here representing the configuration coordinates for which a value is requested; note that these may very well be different from the configuration coordinates actually pertaining to the resource; most implementations will not need to reference this parameter

name - the name of the configuration property for which a value is to be sought; must not be null

Returns:

a suitable ConfigurationValue or null

Throws:

NullPointerException - if resource or name is null

See Also:

getValue(Map, String), AbstractResourceLoadingConfiguration.Resource

getNames

protected abstract Set<String> getNames(AbstractResourceLoadingConfiguration.Resource<? extends T> resource)