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 * @version $Id: SystemConfiguration.java 1842194 2018-09-27 22:24:23Z ggregory $
032 * @since 1.1
033 */
034public class SystemConfiguration extends MapConfiguration
035{
036    /** The logger. */
037    private static Log log = LogFactory.getLog(SystemConfiguration.class);
038
039    /**
040     * Create a Configuration based on the system properties.
041     *
042     * @see System#getProperties
043     */
044    public SystemConfiguration()
045    {
046        super(System.getProperties());
047    }
048
049    /**
050     * Sets system properties from a file specified by its file name. This is
051     * just a short cut for {@code setSystemProperties(null, fileName)}.
052     *
053     * @param fileName The name of the property file.
054     * @throws ConfigurationException if an error occurs.
055     * @since 1.6
056     */
057    public static void setSystemProperties(final String fileName)
058            throws ConfigurationException
059    {
060        setSystemProperties(null, fileName);
061    }
062
063    /**
064     * Sets system properties from a file specified using its base path and
065     * file name. The file can either be a properties file or an XML properties
066     * file. It is loaded, and all properties it contains are added to system
067     * properties.
068     *
069     * @param basePath The base path to look for the property file.
070     * @param fileName The name of the property file.
071     * @throws ConfigurationException if an error occurs.
072     * @since 1.6
073     */
074    public static void setSystemProperties(final String basePath, final String fileName)
075            throws ConfigurationException
076    {
077        final FileBasedConfiguration config =
078                fileName.endsWith(".xml") ? new XMLPropertiesConfiguration()
079                        : new PropertiesConfiguration();
080
081        final FileHandler handler = new FileHandler(config);
082        handler.setBasePath(basePath);
083        handler.setFileName(fileName);
084        handler.load();
085        setSystemProperties(config);
086    }
087
088    /**
089     * Set System properties from a configuration object.
090     * @param systemConfig The configuration containing the properties to be set.
091     * @since 1.6
092     */
093    public static void setSystemProperties(final Configuration systemConfig)
094    {
095        final Iterator<String> iter = systemConfig.getKeys();
096        while (iter.hasNext())
097        {
098            final String key = iter.next();
099            final String value = (String) systemConfig.getProperty(key);
100            if (log.isDebugEnabled())
101            {
102                log.debug("Setting system property " + key + " to " + value);
103            }
104            System.setProperty(key, value);
105        }
106    }
107
108    /**
109     * {@inheritDoc} This implementation returns a snapshot of the keys in the
110     * system properties. If another thread modifies system properties concurrently,
111     * these changes are not reflected by the iterator returned by this method.
112     */
113    @Override
114    protected Iterator<String> getKeysInternal()
115    {
116        return System.getProperties().stringPropertyNames().iterator();
117    }
118}