    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 *     https://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;
    021import java.util.Objects;
    022
    023import org.apache.commons.configuration2.ex.ConfigurationException;
    024import org.apache.commons.configuration2.io.FileHandler;
    025import org.apache.commons.logging.Log;
    026import org.apache.commons.logging.LogFactory;
    027
    028/**
    029 * A configuration based on the system properties.
    030 *
    031 * @since 1.1
    032 */
    033public class SystemConfiguration extends MapConfiguration {
    034
    035    /** The logger. */
    036    private static final Log LOG = LogFactory.getLog(SystemConfiguration.class);
    037
    038    /**
    039     * Sets System properties from a configuration object.
    040     *
    041     * @param systemConfig The configuration containing the properties to be set.
    042     * @since 1.6
    043     */
    044    public static void setSystemProperties(final Configuration systemConfig) {
    045        systemConfig.forEach((k, v) -> {
    046            if (LOG.isDebugEnabled()) {
    047                LOG.debug("Setting system property " + k + " to " + v);
    048            }
    049            System.setProperty(k, Objects.toString(v, null));
    050        });
    051    }
    052
    053    /**
    054     * Sets system properties from a file specified by its file name. This is just a short cut for
    055     * {@code setSystemProperties(null, fileName)}.
    056     *
    057     * @param fileName The name of the property file.
    058     * @throws ConfigurationException if an error occurs.
    059     * @since 1.6
    060     */
    061    public static void setSystemProperties(final String fileName) throws ConfigurationException {
    062        setSystemProperties(null, fileName);
    063    }
    064
    065    /**
    066     * Sets system properties from a file specified using its base path and file name. The file can either be a properties
    067     * file or an XML properties file. It is loaded, and all properties it contains are added to system 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) throws ConfigurationException {
    075        final FileBasedConfiguration config = fileName.endsWith(".xml") ? new XMLPropertiesConfiguration() : new PropertiesConfiguration();
    076        final FileHandler handler = new FileHandler(config);
    077        handler.setBasePath(basePath);
    078        handler.setFileName(fileName);
    079        handler.load();
    080        setSystemProperties(config);
    081    }
    082
    083    /**
    084     * Create a Configuration based on the system properties.
    085     *
    086     * @see System#getProperties
    087     */
    088    public SystemConfiguration() {
    089        super(System.getProperties());
    090    }
    091
    092    /**
    093     * {@inheritDoc} This implementation returns a snapshot of the keys in the system properties. If another thread modifies
    094     * system properties concurrently, these changes are not reflected by the iterator returned by this method.
    095     */
    096    @Override
    097    protected Iterator<String> getKeysInternal() {
    098        return System.getProperties().stringPropertyNames().iterator();
    099    }
    100}