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Tools to assist in the reading of configuration/preferences files in
various formats
/*
* 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.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
import java.util.ListIterator;
/**
* This Configuration class allows you to add multiple different types of Configuration
* to this CompositeConfiguration. If you add Configuration1, and then Configuration2,
* any properties shared will mean that Configuration1 will be returned.
* You can add multiple different types or the same type of properties file.
* If Configuration1 doesn't have the property, then Configuration2 will be checked.
*
* @author Eric Pugh
* @author Henning P. Schmiedehausen
* @version $Id: CompositeConfiguration.java 705028 2008-10-15 20:33:35Z oheger $
*/
public class CompositeConfiguration extends AbstractConfiguration
implements Cloneable
{
/** List holding all the configuration */
private List configList = new LinkedList();
/**
* Configuration that holds in memory stuff. Inserted as first so any
* setProperty() override anything else added.
*/
private Configuration inMemoryConfiguration;
/**
* Creates an empty CompositeConfiguration object which can then
* be added some other Configuration files
*/
public CompositeConfiguration()
{
clear();
}
/**
* Creates a CompositeConfiguration object with a specified in memory
* configuration. This configuration will store any changes made to
* the CompositeConfiguration.
*
* @param inMemoryConfiguration the in memory configuration to use
*/
public CompositeConfiguration(Configuration inMemoryConfiguration)
{
configList.clear();
this.inMemoryConfiguration = inMemoryConfiguration;
configList.add(inMemoryConfiguration);
}
/**
* Create a CompositeConfiguration with an empty in memory configuration
* and adds the collection of configurations specified.
*
* @param configurations the collection of configurations to add
*/
public CompositeConfiguration(Collection configurations)
{
this(new BaseConfiguration(), configurations);
}
/**
* Creates a CompositeConfiguration with a specified in memory
* configuration, and then adds the given collection of configurations.
*
* @param inMemoryConfiguration the in memory configuration to use
* @param configurations the collection of configurations to add
*/
public CompositeConfiguration(Configuration inMemoryConfiguration, Collection configurations)
{
this(inMemoryConfiguration);
if (configurations != null)
{
Iterator it = configurations.iterator();
while (it.hasNext())
{
addConfiguration((Configuration) it.next());
}
}
}
/**
* Add a configuration.
*
* @param config the configuration to add
*/
public void addConfiguration(Configuration config)
{
if (!configList.contains(config))
{
// As the inMemoryConfiguration contains all manually added keys,
// we must make sure that it is always last. "Normal", non composed
// configuration add their keys at the end of the configuration and
// we want to mimic this behaviour.
configList.add(configList.indexOf(inMemoryConfiguration), config);
if (config instanceof AbstractConfiguration)
{
((AbstractConfiguration) config).setThrowExceptionOnMissing(isThrowExceptionOnMissing());
}
}
}
/**
* Remove a configuration. The in memory configuration cannot be removed.
*
* @param config The configuration to remove
*/
public void removeConfiguration(Configuration config)
{
// Make sure that you can't remove the inMemoryConfiguration from
// the CompositeConfiguration object
if (!config.equals(inMemoryConfiguration))
{
configList.remove(config);
}
}
/**
* Return the number of configurations.
*
* @return the number of configuration
*/
public int getNumberOfConfigurations()
{
return configList.size();
}
/**
* Remove all configuration reinitialize the in memory configuration.
*/
public void clear()
{
configList.clear();
// recreate the in memory configuration
inMemoryConfiguration = new BaseConfiguration();
((BaseConfiguration) inMemoryConfiguration).setThrowExceptionOnMissing(isThrowExceptionOnMissing());
((BaseConfiguration) inMemoryConfiguration).setListDelimiter(getListDelimiter());
((BaseConfiguration) inMemoryConfiguration).setDelimiterParsingDisabled(isDelimiterParsingDisabled());
configList.add(inMemoryConfiguration);
}
/**
* Add this property to the inmemory Configuration.
*
* @param key The Key to add the property to.
* @param token The Value to add.
*/
protected void addPropertyDirect(String key, Object token)
{
inMemoryConfiguration.addProperty(key, token);
}
/**
* Read property from underlying composite
*
* @param key key to use for mapping
*
* @return object associated with the given configuration key.
*/
public Object getProperty(String key)
{
Configuration firstMatchingConfiguration = null;
for (Iterator i = configList.iterator(); i.hasNext();)
{
Configuration config = (Configuration) i.next();
if (config.containsKey(key))
{
firstMatchingConfiguration = config;
break;
}
}
if (firstMatchingConfiguration != null)
{
return firstMatchingConfiguration.getProperty(key);
}
else
{
return null;
}
}
public Iterator getKeys()
{
List keys = new ArrayList();
for (Iterator i = configList.iterator(); i.hasNext();)
{
Configuration config = (Configuration) i.next();
Iterator j = config.getKeys();
while (j.hasNext())
{
String key = (String) j.next();
if (!keys.contains(key))
{
keys.add(key);
}
}
}
return keys.iterator();
}
public Iterator getKeys(String key)
{
List keys = new ArrayList();
for (Iterator i = configList.iterator(); i.hasNext();)
{
Configuration config = (Configuration) i.next();
Iterator j = config.getKeys(key);
while (j.hasNext())
{
String newKey = (String) j.next();
if (!keys.contains(newKey))
{
keys.add(newKey);
}
}
}
return keys.iterator();
}
public boolean isEmpty()
{
boolean isEmpty = true;
for (Iterator i = configList.iterator(); i.hasNext();)
{
Configuration config = (Configuration) i.next();
if (!config.isEmpty())
{
return false;
}
}
return isEmpty;
}
protected void clearPropertyDirect(String key)
{
for (Iterator i = configList.iterator(); i.hasNext();)
{
Configuration config = (Configuration) i.next();
config.clearProperty(key);
}
}
public boolean containsKey(String key)
{
for (Iterator i = configList.iterator(); i.hasNext();)
{
Configuration config = (Configuration) i.next();
if (config.containsKey(key))
{
return true;
}
}
return false;
}
public List getList(String key, List defaultValue)
{
List list = new ArrayList();
// add all elements from the first configuration containing the requested key
Iterator it = configList.iterator();
while (it.hasNext() && list.isEmpty())
{
Configuration config = (Configuration) it.next();
if (config != inMemoryConfiguration && config.containsKey(key))
{
appendListProperty(list, config, key);
}
}
// add all elements from the in memory configuration
appendListProperty(list, inMemoryConfiguration, key);
if (list.isEmpty())
{
return defaultValue;
}
ListIterator lit = list.listIterator();
while (lit.hasNext())
{
lit.set(interpolate(lit.next()));
}
return list;
}
public String[] getStringArray(String key)
{
List list = getList(key);
// transform property values into strings
String[] tokens = new String[list.size()];
for (int i = 0; i < tokens.length; i++)
{
tokens[i] = String.valueOf(list.get(i));
}
return tokens;
}
/**
* Return the configuration at the specified index.
*
* @param index The index of the configuration to retrieve
* @return the configuration at this index
*/
public Configuration getConfiguration(int index)
{
return (Configuration) configList.get(index);
}
/**
* Returns the "in memory configuration". In this configuration
* changes are stored.
*
* @return the in memory configuration
*/
public Configuration getInMemoryConfiguration()
{
return inMemoryConfiguration;
}
/**
* Returns a copy of this object. This implementation will create a deep
* clone, i.e. all configurations contained in this composite will also be
* cloned. This only works if all contained configurations support cloning;
* otherwise a runtime exception will be thrown. Registered event handlers
* won't get cloned.
*
* @return the copy
* @since 1.3
*/
public Object clone()
{
try
{
CompositeConfiguration copy = (CompositeConfiguration) super
.clone();
copy.clearConfigurationListeners();
copy.configList = new LinkedList();
copy.inMemoryConfiguration = ConfigurationUtils
.cloneConfiguration(getInMemoryConfiguration());
copy.configList.add(copy.inMemoryConfiguration);
for (int i = 0; i < getNumberOfConfigurations(); i++)
{
Configuration config = getConfiguration(i);
if (config != getInMemoryConfiguration())
{
copy.addConfiguration(ConfigurationUtils
.cloneConfiguration(config));
}
}
return copy;
}
catch (CloneNotSupportedException cnex)
{
// cannot happen
throw new ConfigurationRuntimeException(cnex);
}
}
/**
* Sets a flag whether added values for string properties should be checked
* for the list delimiter. This implementation ensures that the in memory
* configuration is correctly initialized.
*
* @param delimiterParsingDisabled the new value of the flag
* @since 1.4
*/
public void setDelimiterParsingDisabled(boolean delimiterParsingDisabled)
{
((BaseConfiguration) getInMemoryConfiguration())
.setDelimiterParsingDisabled(delimiterParsingDisabled);
super.setDelimiterParsingDisabled(delimiterParsingDisabled);
}
/**
* Sets the character that is used as list delimiter. This implementation
* ensures that the in memory configuration is correctly initialized.
*
* @param listDelimiter the new list delimiter character
* @since 1.4
*/
public void setListDelimiter(char listDelimiter)
{
((BaseConfiguration) getInMemoryConfiguration())
.setListDelimiter(listDelimiter);
super.setListDelimiter(listDelimiter);
}
/**
* Returns the configuration source, in which the specified key is defined.
* This method will iterate over all existing child configurations and check
* whether they contain the specified key. The following constellations are
* possible:
*
* - If exactly one child configuration contains the key, this
* configuration is returned as the source configuration. This may be the
* in memory configuration (this has to be explicitly checked by
* the calling application).
* - If none of the child configurations contain the key, null is
* returned.
* - If the key is contained in multiple child configurations or if the
* key is null, a
IllegalArgumentException is thrown.
* In this case the source configuration cannot be determined.
*
*
* @param key the key to be checked
* @return the source configuration of this key
* @throws IllegalArgumentException if the source configuration cannot be
* determined
* @since 1.5
*/
public Configuration getSource(String key)
{
if (key == null)
{
throw new IllegalArgumentException("Key must not be null!");
}
Configuration source = null;
for (Iterator it = configList.iterator(); it.hasNext();)
{
Configuration conf = (Configuration) it.next();
if (conf.containsKey(key))
{
if (source != null)
{
throw new IllegalArgumentException("The key " + key
+ " is defined by multiple sources!");
}
source = conf;
}
}
return source;
}
/**
* Adds the value of a property to the given list. This method is used by
* getList() for gathering property values from the child
* configurations.
*
* @param dest the list for collecting the data
* @param config the configuration to query
* @param key the key of the property
*/
private static void appendListProperty(List dest, Configuration config,
String key)
{
Object value = config.getProperty(key);
if (value != null)
{
if (value instanceof Collection)
{
dest.addAll((Collection) value);
}
else
{
dest.add(value);
}
}
}
}