/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.commons.configuration;
import java.math.BigDecimal;
import java.math.BigInteger;
import java.util.Iterator;
import java.util.List;
import java.util.Properties;
/**
* <p>The main Configuration interface.</p>
* <p>This interface allows accessing and manipulating a configuration object.
* The major part of the methods defined in this interface deals with accessing
* properties of various data types. There is a generic <code>getProperty()</code>
* method, which returns the value of the queried property in its raw data
* type. Other getter methods try to convert this raw data type into a specific
* data type. If this fails, a <code>ConversionException</code> will be thrown.</p>
* <p>For most of the property getter methods an overloaded version exists that
* allows to specify a default value, which will be returned if the queried
* property cannot be found in the configuration. The behavior of the methods
* that do not take a default value in case of a missing property is not defined
* by this interface and depends on a concrete implementation. E.g. the
* <code>{@link AbstractConfiguration}</code> class, which is the base class
* of most configuration implementations provided by this package, per default
* returns <b>null</b> if a property is not found, but provides the
* <code>{@link org.apache.commons.configuration.AbstractConfiguration#setThrowExceptionOnMissing(boolean)
* setThrowExceptionOnMissing()}</code>
* method, with which it can be configured to throw a <code>NoSuchElementException</code>
* exception in that case. (Note that getter methods for primitive types in
* <code>AbstractConfiguration</code> always throw an exception for missing
* properties because there is no way of overloading the return value.)</p>
* <p>With the <code>addProperty()</code> and <code>setProperty()</code> methods
* new properties can be added to a configuration or the values of properties
* can be changed. With <code>clearProperty()</code> a property can be removed.
* Other methods allow to iterate over the contained properties or to create
* a subset configuration.</p>
*
* @author Commons Configuration team
* @version $Id: Configuration.java 449017 2006-09-22 17:27:00Z oheger $
*/
public interface Configuration
{
/**
* Return a decorator Configuration containing every key from the current
* Configuration that starts with the specified prefix. The prefix is
* removed from the keys in the subset. For example, if the configuration
* contains the following properties:
*
* <pre>
* prefix.number = 1
* prefix.string = Apache
* prefixed.foo = bar
* prefix = Jakarta</pre>
*
* the Configuration returned by <code>subset("prefix")</code> will contain
* the properties:
*
* <pre>
* number = 1
* string = Apache
* = Jakarta</pre>
*
* (The key for the value "Jakarta" is an empty string)
* <p>
* Since the subset is a decorator and not a modified copy of the initial
* Configuration, any change made to the subset is available to the
* Configuration, and reciprocally.
*
* @param prefix The prefix used to select the properties.
* @return a subset configuration
*
* @see SubsetConfiguration
*/
Configuration subset(String prefix);
/**
* Check if the configuration is empty.
*
* @return <code>true</code> if the configuration contains no property,
* <code>false</code> otherwise.
*/
boolean isEmpty();
/**
* Check if the configuration contains the specified key.
*
* @param key the key whose presence in this configuration is to be tested
*
* @return <code>true</code> if the configuration contains a value for this
* key, <code>false</code> otherwise
*/
boolean containsKey(String key);
/**
* Add a property to the configuration. If it already exists then the value
* stated here will be added to the configuration entry. For example, if
* the property:
*
* <pre>resource.loader = file</pre>
*
* is already present in the configuration and you call
*
* <pre>addProperty("resource.loader", "classpath")</pre>
*
* Then you will end up with a List like the following:
*
* <pre>["file", "classpath"]</pre>
*
* @param key The key to add the property to.
* @param value The value to add.
*/
void addProperty(String key, Object value);
/**
* Set a property, this will replace any previously set values. Set values
* is implicitly a call to clearProperty(key), addProperty(key, value).
*
* @param key The key of the property to change
* @param value The new value
*/
void setProperty(String key, Object value);
/**
* Remove a property from the configuration.
*
* @param key the key to remove along with corresponding value.
*/
void clearProperty(String key);
/**
* Remove all properties from the configuration.
*/
void clear();
/**
* Gets a property from the configuration. This is the most basic get
* method for retrieving values of properties. In a typical implementation
* of the <code>Configuration</code> interface the other get methods (that
* return specific data types) will internally make use of this method. On
* this level variable substitution is not yet performed. The returned
* object is an internal representation of the property value for the passed
* in key. It is owned by the <code>Configuration</code> object. So a caller
* should not modify this object. It cannot be guaranteed that this object
* will stay constant over time (i.e. further update operations on the
* configuration may change its internal state).
*
* @param key property to retrieve
* @return the value to which this configuration maps the specified key, or
* null if the configuration contains no mapping for this key.
*/
Object getProperty(String key);
/**
* Get the list of the keys contained in the configuration that match the
* specified prefix.
*
* @param prefix The prefix to test against.
* @return An Iterator of keys that match the prefix.
* @see #getKeys()
*/
Iterator getKeys(String prefix);
/**
* Get the list of the keys contained in the configuration. The returned
* iterator can be used to obtain all defined keys. Note that the exact
* behavior of the iterator's <code>remove()</code> method is specific to
* a concrete implementation. It <em>may</em> remove the corresponding
* property from the configuration, but this is not guaranteed. In any case
* it is no replacement for calling
* <code>{@link #clearProperty(String)}</code> for this property. So it is
* highly recommended to avoid using the iterator's <code>remove()</code>
* method.
*
* @return An Iterator.
*/
Iterator getKeys();
/**
* Get a list of properties associated with the given configuration key.
* This method expects the given key to have an arbitrary number of String
* values, each of which is of the form <code>key=value</code>. These
* strings are splitted at the equals sign, and the key parts will become
* keys of the returned <code>Properties</code> object, the value parts
* become values.
*
* @param key The configuration key.
* @return The associated properties if key is found.
*
* @throws ConversionException is thrown if the key maps to an
* object that is not a String/List.
*
* @throws IllegalArgumentException if one of the tokens is
* malformed (does not contain an equals sign).
*/
Properties getProperties(String key);
/**
* Get a boolean associated with the given configuration key.
*
* @param key The configuration key.
* @return The associated boolean.
*
* @throws ConversionException is thrown if the key maps to an
* object that is not a Boolean.
*/
boolean getBoolean(String key);
/**
* Get a boolean associated with the given configuration key.
* If the key doesn't map to an existing object, the default value
* is returned.
*
* @param key The configuration key.
* @param defaultValue The default value.
* @return The associated boolean.
*
* @throws ConversionException is thrown if the key maps to an
* object that is not a Boolean.
*/
boolean getBoolean(String key, boolean defaultValue);
/**
* Get a {@link Boolean} associated with the given configuration key.
*
* @param key The configuration key.
* @param defaultValue The default value.
* @return The associated boolean if key is found and has valid
* format, default value otherwise.
*
* @throws ConversionException is thrown if the key maps to an
* object that is not a Boolean.
*/
Boolean getBoolean(String key, Boolean defaultValue);
/**
* Get a byte associated with the given configuration key.
*
* @param key The configuration key.
* @return The associated byte.
*
* @throws ConversionException is thrown if the key maps to an
* object that is not a Byte.
*/
byte getByte(String key);
/**
* Get a byte associated with the given configuration key.
* If the key doesn't map to an existing object, the default value
* is returned.
*
* @param key The configuration key.
* @param defaultValue The default value.
* @return The associated byte.
*
* @throws ConversionException is thrown if the key maps to an
* object that is not a Byte.
*/
byte getByte(String key, byte defaultValue);
/**
* Get a {@link Byte} associated with the given configuration key.
*
* @param key The configuration key.
* @param defaultValue The default value.
* @return The associated byte if key is found and has valid format, default
* value otherwise.
*
* @throws ConversionException is thrown if the key maps to an object that
* is not a Byte.
*/
Byte getByte(String key, Byte defaultValue);
/**
* Get a double associated with the given configuration key.
*
* @param key The configuration key.
* @return The associated double.
*
* @throws ConversionException is thrown if the key maps to an
* object that is not a Double.
*/
double getDouble(String key);
/**
* Get a double associated with the given configuration key.
* If the key doesn't map to an existing object, the default value
* is returned.
*
* @param key The configuration key.
* @param defaultValue The default value.
* @return The associated double.
*
* @throws ConversionException is thrown if the key maps to an
* object that is not a Double.
*/
double getDouble(String key, double defaultValue);
/**
* Get a {@link Double} associated with the given configuration key.
*
* @param key The configuration key.
* @param defaultValue The default value.
* @return The associated double if key is found and has valid
* format, default value otherwise.
*
* @throws ConversionException is thrown if the key maps to an
* object that is not a Double.
*/
Double getDouble(String key, Double defaultValue);
/**
* Get a float associated with the given configuration key.
*
* @param key The configuration key.
* @return The associated float.
* @throws ConversionException is thrown if the key maps to an
* object that is not a Float.
*/
float getFloat(String key);
/**
* Get a float associated with the given configuration key.
* If the key doesn't map to an existing object, the default value
* is returned.
*
* @param key The configuration key.
* @param defaultValue The default value.
* @return The associated float.
*
* @throws ConversionException is thrown if the key maps to an
* object that is not a Float.
*/
float getFloat(String key, float defaultValue);
/**
* Get a {@link Float} associated with the given configuration key.
* If the key doesn't map to an existing object, the default value
* is returned.
*
* @param key The configuration key.
* @param defaultValue The default value.
* @return The associated float if key is found and has valid
* format, default value otherwise.
*
* @throws ConversionException is thrown if the key maps to an
* object that is not a Float.
*/
Float getFloat(String key, Float defaultValue);
/**
* Get a int associated with the given configuration key.
*
* @param key The configuration key.
* @return The associated int.
*
* @throws ConversionException is thrown if the key maps to an
* object that is not a Integer.
*/
int getInt(String key);
/**
* Get a int associated with the given configuration key.
* If the key doesn't map to an existing object, the default value
* is returned.
*
* @param key The configuration key.
* @param defaultValue The default value.
* @return The associated int.
*
* @throws ConversionException is thrown if the key maps to an
* object that is not a Integer.
*/
int getInt(String key, int defaultValue);
/**
* Get an {@link Integer} associated with the given configuration key.
* If the key doesn't map to an existing object, the default value
* is returned.
*
* @param key The configuration key.
* @param defaultValue The default value.
* @return The associated int if key is found and has valid format, default
* value otherwise.
*
* @throws ConversionException is thrown if the key maps to an object that
* is not a Integer.
*/
Integer getInteger(String key, Integer defaultValue);
/**
* Get a long associated with the given configuration key.
*
* @param key The configuration key.
* @return The associated long.
*
* @throws ConversionException is thrown if the key maps to an
* object that is not a Long.
*/
long getLong(String key);
/**
* Get a long associated with the given configuration key.
* If the key doesn't map to an existing object, the default value
* is returned.
*
* @param key The configuration key.
* @param defaultValue The default value.
* @return The associated long.
*
* @throws ConversionException is thrown if the key maps to an
* object that is not a Long.
*/
long getLong(String key, long defaultValue);
/**
* Get a {@link Long} associated with the given configuration key.
* If the key doesn't map to an existing object, the default value
* is returned.
*
* @param key The configuration key.
* @param defaultValue The default value.
* @return The associated long if key is found and has valid
* format, default value otherwise.
*
* @throws ConversionException is thrown if the key maps to an
* object that is not a Long.
*/
Long getLong(String key, Long defaultValue);
/**
* Get a short associated with the given configuration key.
*
* @param key The configuration key.
* @return The associated short.
*
* @throws ConversionException is thrown if the key maps to an
* object that is not a Short.
*/
short getShort(String key);
/**
* Get a short associated with the given configuration key.
*
* @param key The configuration key.
* @param defaultValue The default value.
* @return The associated short.
*
* @throws ConversionException is thrown if the key maps to an
* object that is not a Short.
*/
short getShort(String key, short defaultValue);
/**
* Get a {@link Short} associated with the given configuration key.
* If the key doesn't map to an existing object, the default value
* is returned.
*
* @param key The configuration key.
* @param defaultValue The default value.
* @return The associated short if key is found and has valid
* format, default value otherwise.
*
* @throws ConversionException is thrown if the key maps to an
* object that is not a Short.
*/
Short getShort(String key, Short defaultValue);
/**
* Get a {@link BigDecimal} associated with the given configuration key.
*
* @param key The configuration key.
* @return The associated BigDecimal if key is found and has valid format
*/
BigDecimal getBigDecimal(String key);
/**
* Get a {@link BigDecimal} associated with the given configuration key.
* If the key doesn't map to an existing object, the default value
* is returned.
*
* @param key The configuration key.
* @param defaultValue The default value.
*
* @return The associated BigDecimal if key is found and has valid
* format, default value otherwise.
*/
BigDecimal getBigDecimal(String key, BigDecimal defaultValue);
/**
* Get a {@link BigInteger} associated with the given configuration key.
*
* @param key The configuration key.
*
* @return The associated BigInteger if key is found and has valid format
*/
BigInteger getBigInteger(String key);
/**
* Get a {@link BigInteger} associated with the given configuration key.
* If the key doesn't map to an existing object, the default value
* is returned.
*
* @param key The configuration key.
* @param defaultValue The default value.
*
* @return The associated BigInteger if key is found and has valid
* format, default value otherwise.
*/
BigInteger getBigInteger(String key, BigInteger defaultValue);
/**
* Get a string associated with the given configuration key.
*
* @param key The configuration key.
* @return The associated string.
*
* @throws ConversionException is thrown if the key maps to an object that
* is not a String.
*/
String getString(String key);
/**
* Get a string associated with the given configuration key.
* If the key doesn't map to an existing object, the default value
* is returned.
*
* @param key The configuration key.
* @param defaultValue The default value.
* @return The associated string if key is found and has valid
* format, default value otherwise.
*
* @throws ConversionException is thrown if the key maps to an object that
* is not a String.
*/
String getString(String key, String defaultValue);
/**
* Get an array of strings associated with the given configuration key.
* If the key doesn't map to an existing object an empty array is returned
*
* @param key The configuration key.
* @return The associated string array if key is found.
*
* @throws ConversionException is thrown if the key maps to an
* object that is not a String/List of Strings.
*/
String[] getStringArray(String key);
/**
* Get a List of strings associated with the given configuration key.
* If the key doesn't map to an existing object an empty List is returned.
*
* @param key The configuration key.
* @return The associated List.
*
* @throws ConversionException is thrown if the key maps to an
* object that is not a List.
*/
List getList(String key);
/**
* Get a List of strings associated with the given configuration key.
* If the key doesn't map to an existing object, the default value
* is returned.
*
* @param key The configuration key.
* @param defaultValue The default value.
* @return The associated List of strings.
*
* @throws ConversionException is thrown if the key maps to an
* object that is not a List.
*/
List getList(String key, List defaultValue);
}