Package io.confound.config

Class BaseConfiguration<T>

java.lang.Object

io.confound.config.AbstractConfiguration

io.confound.config.BaseConfiguration<T>

Type Parameters:

T - The type of values used in the underlying storage.

All Implemented Interfaces:

Configuration

Direct Known Subclasses:

AbstractObjectConfiguration, AbstractStringConfiguration

public abstract class BaseConfiguration<T>
extends AbstractConfiguration

Abstract configuration implementation providing common base functionality.

Concrete implementations must override findConfigurationValueImpl(String), and may also override hasConfigurationValueImpl(String) for added efficiency.

This class provides a facility normalizeKey(String) for modifying the requested key if necessary before ultimate retrieval via findConfigurationValueImpl(String). Most implementations will not need this facility, and will use the default implementation which uses the requested key unmodified. In any case, the implementation must use the original key, not the normalized key, when delegating to the parent configuration, if any.

Author:

Garret Wilson

Field Summary

Fields inherited from interface io.confound.config.Configuration

KEY_SEGMENT_SEPARATOR

Constructor Summary

Constructors

Constructor	Description
BaseConfiguration()

Method Summary

Modifier and Type	Method	Description
protected <C> java.util.Optional<C>	convertValue(java.util.Optional<T> value, java.lang.Class<C> convertClass)	Converts a configuration value from its actual type in the underlying storage to the requested type.
protected java.util.Optional<T>	findConfigurationValue(java.lang.String key)	Tries to retrieves a general configuration value from the underlying storage.
protected abstract java.util.Optional<T>	findConfigurationValueImpl(java.lang.String key)	Implementation to retrieves a general configuration value that may not be present from the underlying storage.
<O> java.util.Optional<O>	findObject(java.lang.String key, java.lang.Class<O> type)	Retrieves a general configuration object that may not be present as the requested type, converting it as necessary.
boolean	hasConfigurationValue(java.lang.String key)	Determines whether a configuration of some type exists for the given configuration key.
protected boolean	hasConfigurationValueImpl(java.lang.String key)	Determines whether a configuration value is present in the underlying storage.
protected java.lang.String	normalizeKey(java.lang.String key)	Normalizes a requested key if required by this implementation.

Methods inherited from class io.confound.config.AbstractConfiguration

or

Methods inherited from class java.lang.Object

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

Methods inherited from interface io.confound.config.Configuration

createMissingConfigurationKeyException, findBoolean, findDouble, findInt, findLong, findObject, findPath, findString, findUri, getBoolean, getDouble, getInt, getLong, getObject, getObject, getPath, getString, getUri, requireConfiguration, resolvePath, subConfiguration, superConfiguration, withFallback

Constructor Detail

BaseConfiguration

public BaseConfiguration()

Method Detail

normalizeKey

protected java.lang.String normalizeKey(@Nonnull
                                        java.lang.String key)

Normalizes a requested key if required by this implementation.

Implementation Specification:

The default implementation returns the key unmodified after checking for null.

Parameters:

key - The configuration key.

Returns:

The requested configuration key, modified as needed for lookup in this implementation.

convertValue

protected <C> java.util.Optional<C> convertValue(@Nonnull
                                                 java.util.Optional<T> value,
                                                 @Nonnull
                                                 java.lang.Class<C> convertClass)
                                          throws ConfigurationException

Converts a configuration value from its actual type in the underlying storage to the requested type.

Implementation Specification:

This implementation merely checked to see if the value can be cast to the requested type; otherwise, an exception is thrown.

Type Parameters:

C - The requested conversion type.

Parameters:

value - The value to convert.

convertClass - The class indicating the requested conversion type.

Returns:

The value converted to the requested type.

Throws:

ConfigurationException - if the value is present and cannot be converted to the requested type.

hasConfigurationValue

public boolean hasConfigurationValue(@Nonnull
                                     java.lang.String key)
                              throws ConfigurationException

Determines whether a configuration of some type exists for the given configuration key.

Implementation Specification:

This implementation normalizes the key and delegates to hasConfigurationValueImpl(String).

Implementation Note:

Most subclasses should not override this method, and instead override hasConfigurationValueImpl(String).

Parameters:

key - The configuration key.

Returns:

true if a value of any type could be retrieved from this configuration using the given key.

Throws:

java.lang.NullPointerException - if the given key is null.

java.lang.SecurityException - If a security manager exists and it doesn't allow access to the specified configuration.

ConfigurationException - if there is a configuration value stored in an invalid format.

findObject

public <O> java.util.Optional<O> findObject(java.lang.String key,
                                            java.lang.Class<O> type)
                                     throws ConfigurationException

Retrieves a general configuration object that may not be present as the requested type, converting it as necessary. If the object is present but cannot be converted, a ConfigurationException will be thrown.

Implementation Specification:

This implementation converts the value using convertValue(Optional, Class).

Type Parameters:

O - The type of configuration object expected.

Parameters:

key - The configuration key.

type - The type of object requested.

Returns:

The optional configuration value associated with the given key.

Throws:

ConfigurationException - if there is a configuration value stored in an invalid format.

hasConfigurationValueImpl

protected boolean hasConfigurationValueImpl(@Nonnull
                                            java.lang.String key)
                                     throws ConfigurationException

Determines whether a configuration value is present in the underlying storage.

The given configuration key is assumed to already be normalized, and should not be modified.

This method must not fall back to parent configuration; only local values must be returned.

Implementation Specification:

The default implementation delegates to findConfigurationValueImpl(String).

Parameters:

key - The normalized configuration key.

Returns:

true if a value of any type could be retrieved from this configuration using the given key.

Throws:

java.lang.NullPointerException - if the given key is null.

java.lang.SecurityException - If a security manager exists and it doesn't allow access to the specified configuration.

ConfigurationException - if there is a configuration value stored in an invalid format.

findConfigurationValue

protected java.util.Optional<T> findConfigurationValue(@Nonnull
                                                       java.lang.String key)
                                                throws ConfigurationException

Tries to retrieves a general configuration value from the underlying storage. The key need not be normalized; it will be normalized as necessary.

This method must not fall back to parent configuration; only local values must be returned.

Implementation Note:

This is an internal API call that should be used by child classes to funnel requests to the underlying storage. Normally child classes will not override this method, but override findConfigurationValueImpl(String) instead.

Parameters:

key - The configuration key, which may not be normalized.

Returns:

The optional configuration value associated with the given key.

Throws:

java.lang.NullPointerException - if the given key is null.

java.lang.SecurityException - If a security manager exists and it doesn't allow access to the specified configuration.

ConfigurationException - if there is a configuration value stored in an invalid format.

See Also:

normalizeKey(String)

findConfigurationValueImpl

protected abstract java.util.Optional<T> findConfigurationValueImpl(@Nonnull
                                                                    java.lang.String key)
                                                             throws ConfigurationException

Implementation to retrieves a general configuration value that may not be present from the underlying storage.

The given configuration key is assumed to already be normalized, and should not be modified.

This method must not fall back to parent configuration; only local values must be returned.

Parameters:

key - The normalized configuration key.

Returns:

The optional configuration value associated with the given key.

Throws:

java.lang.NullPointerException - if the given key is null.

java.lang.SecurityException - If a security manager exists and it doesn't allow access to the specified configuration.

ConfigurationException - if there is a configuration value stored in an invalid format.