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