    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 * @author Emmanuel Bourg
    031 * @since 1.1
    032 */
    033public class SystemConfiguration extends MapConfiguration
    034{
    035    /** The logger. */
    036    private static Log log = LogFactory.getLog(SystemConfiguration.class);
    037
    038    /**
    039     * Create a Configuration based on the system properties.
    040     *
    041     * @see System#getProperties
    042     */
    043    public SystemConfiguration()
    044    {
    045        super(System.getProperties());
    046    }
    047
    048    /**
    049     * Sets system properties from a file specified by its file name. This is
    050     * just a short cut for {@code setSystemProperties(null, fileName)}.
    051     *
    052     * @param fileName The name of the property file.
    053     * @throws ConfigurationException if an error occurs.
    054     * @since 1.6
    055     */
    056    public static void setSystemProperties(final String fileName)
    057            throws ConfigurationException
    058    {
    059        setSystemProperties(null, fileName);
    060    }
    061
    062    /**
    063     * Sets system properties from a file specified using its base path and
    064     * file name. The file can either be a properties file or an XML properties
    065     * file. It is loaded, and all properties it contains are added to system
    066     * properties.
    067     *
    068     * @param basePath The base path to look for the property file.
    069     * @param fileName The name of the property file.
    070     * @throws ConfigurationException if an error occurs.
    071     * @since 1.6
    072     */
    073    public static void setSystemProperties(final String basePath, final String fileName)
    074            throws ConfigurationException
    075    {
    076        final FileBasedConfiguration config =
    077                fileName.endsWith(".xml") ? new XMLPropertiesConfiguration()
    078                        : new PropertiesConfiguration();
    079
    080        final FileHandler handler = new FileHandler(config);
    081        handler.setBasePath(basePath);
    082        handler.setFileName(fileName);
    083        handler.load();
    084        setSystemProperties(config);
    085    }
    086
    087    /**
    088     * Set System properties from a configuration object.
    089     * @param systemConfig The configuration containing the properties to be set.
    090     * @since 1.6
    091     */
    092    public static void setSystemProperties(final Configuration systemConfig)
    093    {
    094        final Iterator<String> iter = systemConfig.getKeys();
    095        while (iter.hasNext())
    096        {
    097            final String key = iter.next();
    098            final String value = (String) systemConfig.getProperty(key);
    099            if (log.isDebugEnabled())
    100            {
    101                log.debug("Setting system property " + key + " to " + value);
    102            }
    103            System.setProperty(key, value);
    104        }
    105    }
    106
    107    /**
    108     * {@inheritDoc} This implementation returns a snapshot of the keys in the
    109     * system properties. If another thread modifies system properties concurrently,
    110     * these changes are not reflected by the iterator returned by this method.
    111     */
    112    @Override
    113    protected Iterator<String> getKeysInternal()
    114    {
    115        return System.getProperties().stringPropertyNames().iterator();
    116    }
    117}