/* ========================================================================
* JCommon : a free general purpose class library for the Java(tm) platform
* ========================================================================
*
* (C) Copyright 2000-2005, by Object Refinery Limited and Contributors.
*
* Project Info: http://www.jfree.org/jcommon/index.html
*
* This library is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation; either version 2.1 of the License, or
* (at your option) any later version.
*
* This library is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
* License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
* USA.
*
* [Java is a trademark or registered trademark of Sun Microsystems, Inc.
* in the United States and other countries.]
*
* ------------------------------
* HierarchicalConfiguration.java
* ------------------------------
* (C) Copyright 2004, by Object Refinery Limited.
*
* Original Author: Thomas Morgner;
* Contributor(s): David Gilbert (for Object Refinery Limited);
*
* $Id: HierarchicalConfiguration.java,v 1.8 2008/09/10 09:17:28 mungady Exp $
*
* Changes
* -------
* 07-Jun-2004 : Added JCommon header (DG);
* 29-Jul-2004 : Replaced 'enum' variable name (reserved word in JDK 1.5) (DG);
*
*/
package org.jfree.base.config;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.util.Collections;
import java.util.Enumeration;
import java.util.Iterator;
import java.util.Properties;
import java.util.TreeSet;
import org.jfree.util.Configuration;
import org.jfree.util.PublicCloneable;
/**
* A hierarchical configuration. Such a configuration can have one or more
* parent configurations providing usefull default values.
*
* @author Thomas Morgner
*/
public class HierarchicalConfiguration
implements ModifiableConfiguration, PublicCloneable
{
/**
* The instance configuration properties.
*/
private Properties configuration;
/**
* The parent configuration (null if this is the root configuration).
*/
private transient Configuration parentConfiguration;
/**
* Creates a new configuration.
*/
public HierarchicalConfiguration()
{
this.configuration = new Properties();
}
/**
* Creates a new configuration.
*
* @param parentConfiguration the parent configuration.
*/
public HierarchicalConfiguration(final Configuration parentConfiguration)
{
this();
this.parentConfiguration = parentConfiguration;
}
/**
* Returns the configuration property with the specified key.
*
* @param key the property key.
* @return the property value.
*/
public String getConfigProperty(final String key)
{
return getConfigProperty(key, null);
}
/**
* Returns the configuration property with the specified key (or the
* specified default value if there is no such property).
* <p/>
* If the property is not defined in this configuration, the code will
* lookup the property in the parent configuration.
*
* @param key the property key.
* @param defaultValue the default value.
* @return the property value.
*/
public String getConfigProperty(final String key, final String defaultValue)
{
String value = this.configuration.getProperty(key);
if (value == null)
{
if (isRootConfig())
{
value = defaultValue;
}
else
{
value = this.parentConfiguration.getConfigProperty(key, defaultValue);
}
}
return value;
}
/**
* Sets a configuration property.
*
* @param key the property key.
* @param value the property value.
*/
public void setConfigProperty(final String key, final String value)
{
if (key == null)
{
throw new NullPointerException();
}
if (value == null)
{
this.configuration.remove(key);
}
else
{
this.configuration.setProperty(key, value);
}
}
/**
* Returns true if this object has no parent.
*
* @return true, if this report is the root configuration, false otherwise.
*/
private boolean isRootConfig()
{
return this.parentConfiguration == null;
}
/**
* Checks, whether the given key is localy defined in this instance or
* whether the key's value is inherited.
*
* @param key the key that should be checked.
* @return true, if the key is defined locally, false otherwise.
*/
public boolean isLocallyDefined(final String key)
{
return this.configuration.containsKey(key);
}
/**
* Returns the collection of properties for the configuration.
*
* @return the properties.
*/
protected Properties getConfiguration()
{
return this.configuration;
}
/**
* The new configuartion will be inserted into the list of report
* configuration, so that this configuration has the given report
* configuration instance as parent.
*
* @param config the new report configuration.
*/
public void insertConfiguration(final HierarchicalConfiguration config)
{
config.setParentConfig(getParentConfig());
setParentConfig(config);
}
/**
* Set the parent configuration. The parent configuration is queried, if the
* requested configuration values was not found in this report
* configuration.
*
* @param config the parent configuration.
*/
protected void setParentConfig(final Configuration config)
{
if (this.parentConfiguration == this)
{
throw new IllegalArgumentException("Cannot add myself as parent configuration.");
}
this.parentConfiguration = config;
}
/**
* Returns the parent configuration. The parent configuration is queried, if
* the requested configuration values was not found in this report
* configuration.
*
* @return the parent configuration.
*/
protected Configuration getParentConfig()
{
return this.parentConfiguration;
}
/**
* Returns all defined configuration properties for the report. The
* enumeration contains all keys of the changed properties, properties set
* from files or the system properties are not included.
*
* @return all defined configuration properties for the report.
*/
public Enumeration getConfigProperties()
{
return this.configuration.keys();
}
/**
* Searches all property keys that start with a given prefix.
*
* @param prefix the prefix that all selected property keys should share
* @return the properties as iterator.
*/
public Iterator findPropertyKeys(final String prefix)
{
final TreeSet keys = new TreeSet();
collectPropertyKeys(prefix, this, keys);
return Collections.unmodifiableSet(keys).iterator();
}
/**
* Collects property keys from this and all parent report configurations,
* which start with the given prefix.
*
* @param prefix the prefix, that selects the property keys.
* @param config the currently processed report configuration.
* @param collector the target list, that should receive all valid keys.
*/
private void collectPropertyKeys(final String prefix,
final Configuration config,
final TreeSet collector)
{
final Enumeration enum1 = config.getConfigProperties();
while (enum1.hasMoreElements())
{
final String key = (String) enum1.nextElement();
if (key.startsWith(prefix))
{
if (collector.contains(key) == false)
{
collector.add(key);
}
}
}
if (config instanceof HierarchicalConfiguration)
{
final HierarchicalConfiguration hconfig = (HierarchicalConfiguration) config;
if (hconfig.parentConfiguration != null)
{
collectPropertyKeys(prefix, hconfig.parentConfiguration, collector);
}
}
}
/**
* Checks, whether the parent configuration can be serialized. Usually the
* global configuration is not serialized and should return false here.
*
* @return true, if the parent config can be serialized, false otherwise.
*/
protected boolean isParentSaved()
{
return true;
}
/**
* A callback method to reconnect this configuration with the global
* configuration after deserialization.
*/
protected void configurationLoaded()
{
}
/**
* Helper method for serialization.
*
* @param out the output stream where to write the object.
* @throws java.io.IOException if errors occur while writing the stream.
*/
private void writeObject(final ObjectOutputStream out)
throws IOException
{
out.defaultWriteObject();
if (isParentSaved() == false)
{
out.writeBoolean(false);
}
else
{
out.writeBoolean(true);
out.writeObject(this.parentConfiguration);
}
}
/**
* Helper method for serialization.
*
* @param in the input stream from where to read the serialized object.
* @throws IOException when reading the stream fails.
* @throws ClassNotFoundException if a class definition for a serialized
* object could not be found.
*/
private void readObject(final ObjectInputStream in)
throws IOException, ClassNotFoundException
{
in.defaultReadObject();
final boolean readParent = in.readBoolean();
if (readParent)
{
this.parentConfiguration = (ModifiableConfiguration) in.readObject();
}
else
{
this.parentConfiguration = null;
}
configurationLoaded();
}
/**
* Returns a clone of this instance.
*
* @return A clone.
*
* @throws CloneNotSupportedException if there is a problem cloning.
*/
public Object clone() throws CloneNotSupportedException
{
HierarchicalConfiguration config = (HierarchicalConfiguration) super.clone();
config.configuration = (Properties) this.configuration.clone();
return config;
}
}