org.microbean.microprofile.config

Class MicroProfileConfigProperties

java.lang.Object

java.util.Dictionary<K,V>

java.util.Hashtable<Object,Object>

java.util.Properties

org.microbean.microprofile.config.MicroProfileConfigProperties

All Implemented Interfaces:

Serializable, Cloneable, Map<Object,Object>

public class MicroProfileConfigProperties
extends Properties

A Properties implementation that wraps a Config and is suitable for installing as System properties.

This class intentionally violates several tenets of the Map interface and Properties class. Deviations and oddities are noted below.

• The Hashtable.clear() method, while supported, cannot, and therefore does not, remove any items from the Config that is expressed by this class. It will remove all items manually put into a MicroProfileConfigProperties instance directly.
• Because the MicroProfile Config specification does not say anything about concurrent access to methods like Config.getPropertyNames(), all iteration methods in this class should be regarded as producing unmodifiable snapshots of a rough estimate of the keys present in a MicroProfileConfigProperties instance.
• All iteration return values are immutable and will throw UnsupportedOperationException where appropriate.
• Because the MicroProfile Config specification does not say anything about the underlying dynamic nature of the configuration systems that a given Config abstracts, it is possible, for example, for the containsKey(Object) method to return true, and then for get(Object) to be unable to retrieve a value.
• Because the MicroProfile Config specification does not say anything about what implementations must do with regards to caching or freshness, it is strictly speaking undefined whether fresh or stale results will be retrieved by instances of this class.

Thread Safety

This class is safe for concurrent use by multiple threads.

Author:

Laird Nelson

See Also:

Config, Serialized Form

Field Summary

Fields inherited from class java.util.Properties

defaults

Constructor Summary

Constructors

Constructor and Description
MicroProfileConfigProperties() Creates a new MicroProfileConfigProperties representing the Config that results from ConfigProvider.getConfig().
MicroProfileConfigProperties(Config config) Creates a new MicroProfileConfigProperties wrapping the supplied Config.
MicroProfileConfigProperties(Config config, Properties defaults) Creates a new MicroProfileConfigProperties using the supplied Properties as its defaults and wrapping the supplied Config.
MicroProfileConfigProperties(Properties defaults) Creates a new MicroProfileConfigProperties using the supplied Properties as its defaults and wrapping the Config that results from ConfigProvider.getConfig().

Method Summary

Modifier and Type	Method and Description
boolean	contains(Object value) Invokes the containsValue(Object) method with the supplied Object and returns the result.
boolean	containsKey(Object key) Returns true if this MicroProfileConfigProperties directly contains the supplied key, or if the supplied key is a String and is contained in the Set of configuration property names returned by the Config.getPropertyNames() method.
boolean	containsValue(Object value) Returns true if this MicroProfileConfigProperties contains the supplied value Object.
Enumeration<Object>	elements() Returns a non-null Enumeration constructed atop the Iterator supplied by the Collection returned by an invocation of this MicroProfileConfigProperties' values() method.
Set<Map.Entry<Object,Object>>	entrySet() Returns a non-null immutable Set of immutable Entry instances representing this MicroProfileConfigProperties' entries.
Object	get(Object key) Returns the value indexed under the supplied key, or null if the value does not exist.
String	getProperty(String key) Returns the String value indexed under the supplied key.
static void	installAsSystemProperties() Installs an instance of MicroProfileConfigProperties somewhat irrevocably as the system properties, with the current system properties as its defaults.
boolean	isEmpty() Returns true if this MicroProfileConfigProperties is empty.
Enumeration<Object>	keys() Invokes the keySet() method and returns its return value.
Set<Object>	keySet() Returns a non-null, immutable Set of Objects that contains the keys stored directly by this MicroProfileConfigProperties or that are contained in the return value of a Config.getPropertyNames() invocation.
int	size() Returns the size of this MicroProfileConfigProperties as expressed by the size of its key set.
Collection<Object>	values() Returns a non-null, immutable Collection of this MicroProfileConfigProperties' values.

Methods inherited from class java.util.Properties

getProperty, list, list, load, load, loadFromXML, propertyNames, save, setProperty, store, store, storeToXML, storeToXML, stringPropertyNames

Methods inherited from class java.util.Hashtable

clear, clone, compute, computeIfAbsent, computeIfPresent, equals, forEach, getOrDefault, hashCode, merge, put, putAll, putIfAbsent, rehash, remove, remove, replace, replace, replaceAll, toString

Methods inherited from class java.lang.Object

finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

MicroProfileConfigProperties

public MicroProfileConfigProperties()

Creates a new MicroProfileConfigProperties representing the Config that results from ConfigProvider.getConfig().

See Also:

ConfigProvider.getConfig()

MicroProfileConfigProperties

public MicroProfileConfigProperties(Config config)

Creates a new MicroProfileConfigProperties wrapping the supplied Config.

Parameters:

config - the Config to express; may be null in which case the return value of ConfigProvider.getConfig() will be used instead

See Also:

ConfigProvider.getConfig()

MicroProfileConfigProperties

public MicroProfileConfigProperties(Properties defaults)

Creates a new MicroProfileConfigProperties using the supplied Properties as its defaults and wrapping the Config that results from ConfigProvider.getConfig().

Parameters:

defaults - the default Properties; may be null

See Also:

Properties.defaults, ConfigProvider.getConfig()

MicroProfileConfigProperties

public MicroProfileConfigProperties(Config config,
                                    Properties defaults)

Creates a new MicroProfileConfigProperties using the supplied Properties as its defaults and wrapping the supplied Config.

Parameters:

config - the Config to express; may be null in which case the return value of ConfigProvider.getConfig() will be used instead

defaults - the default Properties; may be null

See Also:

ConfigProvider.getConfig()

Method Detail

containsKey

public final boolean containsKey(Object key)

Returns true if this MicroProfileConfigProperties directly contains the supplied key, or if the supplied key is a String and is contained in the Set of configuration property names returned by the Config.getPropertyNames() method.

Thread Safety

This method is safe for concurrent use by multiple threads.

Specified by:

containsKey in interface Map<Object,Object>

Overrides:

containsKey in class Hashtable<Object,Object>

Parameters:

key - the key to seek; may be null

Returns:

true if this MicroProfileConfigProperties directly contains the supplied key, or if the supplied key is a String and is contained in the Set of configuration property names returned by the Config.getPropertyNames() method; false otherwise

contains

public final boolean contains(Object value)

Invokes the containsValue(Object) method with the supplied Object and returns the result.

Thread Safety

This method is safe for concurrent use by multiple threads.

Overrides:

contains in class Hashtable<Object,Object>

Parameters:

value - the value to seek; may be null

Returns:

true if the containsValue(Object) method returns true; false otherwise

See Also:

containsValue(Object)

containsValue

public final boolean containsValue(Object value)

Returns true if this MicroProfileConfigProperties contains the supplied value Object.

First the Hashtable.containsValue(Object) method is invoked with the supplied Object. If that returns true, then true is returned.

Next, all known property names in the Config wrapped by this MicroProfileConfigProperties are acquired. This set is iterated over and Config.getOptionalValue(String, Class) is called for each one. If the resulting Optional is present, then true is returned.

In all other cases false is returned.

Thread Safety

This method is safe for concurrent use by multiple threads.

Specified by:

containsValue in interface Map<Object,Object>

Overrides:

containsValue in class Hashtable<Object,Object>

Parameters:

value - the value to seek; may be null

Returns:

true if this MicroProfileConfigProperties contains the supplied value; false otherwise

See Also:

Config.getPropertyNames(), Hashtable.containsValue(Object)

getProperty

public final String getProperty(String key)

Returns the String value indexed under the supplied key.

This method may return null.

This implementation first calls get(Object). If the result is a non-null String, then it is returned. Otherwise, if the Properties.defaults field is non-null, then Properties.getProperty(String) is invoked on it with the supplied key and the result is returned. In all other cases null is returned.

Thread Safety

This method is safe for concurrent use by multiple threads.

Overrides:

getProperty in class Properties

Parameters:

key - the key of the value to return; may be null

Returns:

an appropriate value, or null

See Also:

get(Object), Properties.defaults, Properties.getProperty(String)

get

public final Object get(Object key)

Returns the value indexed under the supplied key, or null if the value does not exist. Note that a null return value could result from a key's being explicitly mapped to null, or from a key's absence.

This implementation first calls Hashtable.containsKey(Object) with the supplied key. If that method invocation returns true, then the Hashtable.get(Object) method is invoked and its result is returned.

Otherwise, the Config.getOptionalValue(String, Class) method is called and its resulting Optional result is acquired and returned, or, if it is not present, null is returned.

Thread Safety

This method is safe for concurrent use by multiple threads.

Specified by:

get in interface Map<Object,Object>

Overrides:

get in class Hashtable<Object,Object>

Parameters:

key - the key of the value to return; may be null

Returns:

an appropriate value, or null

See Also:

Hashtable.containsKey(Object), Hashtable.get(Object), Config.getOptionalValue(String, Class)

isEmpty

public final boolean isEmpty()

Returns true if this MicroProfileConfigProperties is empty. In all normal cases, this method will return false, since normally Config instances expose at least one configuration property value.

This implementation calls the Hashtable.isEmpty() method. If that method returns false, then false is returned.

Otherwise this method calls the Config.getPropertyNames() method, calls Iterable.iterator() on the resulting Iterable, and, if it is non-null, calls the Iterator.hasNext() method on it, returning its result.

In all other cases this method returns true.

This method is a much faster way of checking if this MicroProfileConfigProperties' size is 0.

Thread Safety

This method is safe for concurrent use by multiple threads.

Specified by:

isEmpty in interface Map<Object,Object>

Overrides:

isEmpty in class Hashtable<Object,Object>

Returns:

true, rarely, if this MicroProfileConfigProperties is empty; false otherwise

See Also:

Hashtable.isEmpty(), Config.getPropertyNames()

size

public final int size()

Returns the size of this MicroProfileConfigProperties as expressed by the size of its key set.

This method returns ints that are greater than or equal to zero.

This method rarely returns 0 given the fact that a Config normally expresses at least one configuration property value.

Use the isEmpty() method for a much, much faster way to check for a size of 0.

Thread Safety

This method is safe for concurrent use by multiple threads.

Specified by:

size in interface Map<Object,Object>

Overrides:

size in class Hashtable<Object,Object>

Returns:

the size of this MicroProfileConfigProperties

See Also:

keySet(), isEmpty()

keys

public final Enumeration<Object> keys()

Invokes the keySet() method and returns its return value.

This method never returns null.

Thread Safety

This method is safe for concurrent use by multiple threads.

Overrides:

keys in class Hashtable<Object,Object>

Returns:

the result of invoking the keySet() method.

See Also:

keySet()

keySet

public final Set<Object> keySet()

Returns a non-null, immutable Set of Objects that contains the keys stored directly by this MicroProfileConfigProperties or that are contained in the return value of a Config.getPropertyNames() invocation.

The Set of Objects returned by this method is a disconnected snapshot in time of the keys that were thought to be in this MicroProfileConfigProperties at the time the snapshot was constructed. Changes to this MicroProfileConfigProperties are not reflected in the Set.

Thread Safety

This method is safe for concurrent use by multiple threads.

The Set returned by this method is safe for concurrent use by multiple threads.

Specified by:

keySet in interface Map<Object,Object>

Overrides:

keySet in class Hashtable<Object,Object>

Returns:

a non-null, immutable Set of Objects that contains the keys stored directly by this MicroProfileConfigProperties or that are contained in the return value of a Config.getPropertyNames() invocation

See Also:

Hashtable.keySet(), Config.getPropertyNames()

elements

public final Enumeration<Object> elements()

Returns a non-null Enumeration constructed atop the Iterator supplied by the Collection returned by an invocation of this MicroProfileConfigProperties' values() method.

Thread Safety

This method is safe for concurrent use by multiple threads.

Overrides:

elements in class Hashtable<Object,Object>

Returns:

a non-null Enumeration over the values directly contained by this MicroProfileConfigProperties or indirectly accessible via calls to Config.getOptionalValue(String, Class)

See Also:

values(), Config.getPropertyNames(), Config.getOptionalValue(String, Class)

values

public final Collection<Object> values()

Returns a non-null, immutable Collection of this MicroProfileConfigProperties' values.

The values returned are those stored directly (via calls to Hashtable.put(Object, Object), for example) or stored implicitly as configuration values accessible via calls to Config.getOptionalValue(String, Class).

Changes in this MicroProfileConfigProperties are not reflected in the returned Collection.

Thread Safety

This method is safe for concurrent use by multiple threads.

Specified by:

values in interface Map<Object,Object>

Overrides:

values in class Hashtable<Object,Object>

Returns:

a non-null, immutable Collection of this MicroProfileConfigProperties' values

See Also:

Config.getPropertyNames(), Config.getOptionalValue(String, Class)

entrySet

public final Set<Map.Entry<Object,Object>> entrySet()

Returns a non-null immutable Set of immutable Entry instances representing this MicroProfileConfigProperties' entries.

The entries returned are those that result from calls to Hashtable.put(Object, Object) and similar methods, and from configuration property values accessible via calls to Config.getOptionalValue(String, Class).

This method calls the keySet() and get(Object) methods.

Iteration order of the returned Set is not defined, with the exception that entries stored directly come at the head of the returned Set.

Thread Safety

This method is safe for concurrent use by multiple threads.

Specified by:

entrySet in interface Map<Object,Object>

Overrides:

entrySet in class Hashtable<Object,Object>

Returns:

a non-null immutable Set of immutable Entry instances representing this MicroProfileConfigProperties' entries

See Also:

Config.getPropertyNames(), Config.getOptionalValue(String, Class)

installAsSystemProperties

public static final void installAsSystemProperties()

Installs an instance of MicroProfileConfigProperties somewhat irrevocably as the system properties, with the current system properties as its defaults.

Thread Safety

This method is safe for concurrent use by multiple threads.

Throws:

SecurityException - if permission is not granted