    001/*
    002 * Licensed to the Apache Software Foundation (ASF) under one or more
    003 * contributor license agreements.  See the NOTICE file distributed with
    004 * this work for additional information regarding copyright ownership.
    005 * The ASF licenses this file to You under the Apache License, Version 2.0
    006 * (the "License"); you may not use this file except in compliance with
    007 * the License.  You may obtain a copy of the License at
    008 *
    009 *     http://www.apache.org/licenses/LICENSE-2.0
    010 *
    011 * Unless required by applicable law or agreed to in writing, software
    012 * distributed under the License is distributed on an "AS IS" BASIS,
    013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    014 * See the License for the specific language governing permissions and
    015 * limitations under the License.
    016 */
    017
    018package org.apache.commons.configuration2;
    019
    020import java.util.Iterator;
    021
    022import org.apache.commons.configuration2.ex.ConfigurationException;
    023import org.apache.commons.configuration2.io.FileHandler;
    024import org.apache.commons.logging.Log;
    025import org.apache.commons.logging.LogFactory;
    026
    027/**
    028 * A configuration based on the system properties.
    029 *
    030 * @since 1.1
    031 */
    032public class SystemConfiguration extends MapConfiguration
    033{
    034    /** The logger. */
    035    private static Log log = LogFactory.getLog(SystemConfiguration.class);
    036
    037    /**
    038     * Create a Configuration based on the system properties.
    039     *
    040     * @see System#getProperties
    041     */
    042    public SystemConfiguration()
    043    {
    044        super(System.getProperties());
    045    }
    046
    047    /**
    048     * Sets system properties from a file specified by its file name. This is
    049     * just a short cut for {@code setSystemProperties(null, fileName)}.
    050     *
    051     * @param fileName The name of the property file.
    052     * @throws ConfigurationException if an error occurs.
    053     * @since 1.6
    054     */
    055    public static void setSystemProperties(final String fileName)
    056            throws ConfigurationException
    057    {
    058        setSystemProperties(null, fileName);
    059    }
    060
    061    /**
    062     * Sets system properties from a file specified using its base path and
    063     * file name. The file can either be a properties file or an XML properties
    064     * file. It is loaded, and all properties it contains are added to system
    065     * properties.
    066     *
    067     * @param basePath The base path to look for the property file.
    068     * @param fileName The name of the property file.
    069     * @throws ConfigurationException if an error occurs.
    070     * @since 1.6
    071     */
    072    public static void setSystemProperties(final String basePath, final String fileName)
    073            throws ConfigurationException
    074    {
    075        final FileBasedConfiguration config =
    076                fileName.endsWith(".xml") ? new XMLPropertiesConfiguration()
    077                        : new PropertiesConfiguration();
    078
    079        final FileHandler handler = new FileHandler(config);
    080        handler.setBasePath(basePath);
    081        handler.setFileName(fileName);
    082        handler.load();
    083        setSystemProperties(config);
    084    }
    085
    086    /**
    087     * Set System properties from a configuration object.
    088     * @param systemConfig The configuration containing the properties to be set.
    089     * @since 1.6
    090     */
    091    public static void setSystemProperties(final Configuration systemConfig)
    092    {
    093        final Iterator<String> iter = systemConfig.getKeys();
    094        while (iter.hasNext())
    095        {
    096            final String key = iter.next();
    097            final String value = (String) systemConfig.getProperty(key);
    098            if (log.isDebugEnabled())
    099            {
    100                log.debug("Setting system property " + key + " to " + value);
    101            }
    102            System.setProperty(key, value);
    103        }
    104    }
    105
    106    /**
    107     * {@inheritDoc} This implementation returns a snapshot of the keys in the
    108     * system properties. If another thread modifies system properties concurrently,
    109     * these changes are not reflected by the iterator returned by this method.
    110     */
    111    @Override
    112    protected Iterator<String> getKeysInternal()
    113    {
    114        return System.getProperties().stringPropertyNames().iterator();
    115    }
    116}