    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;
    021import java.util.List;
    022import java.util.Map;
    023import java.util.Properties;
    024
    025import org.apache.commons.configuration2.convert.ListDelimiterHandler;
    026import org.apache.commons.lang3.StringUtils;
    027
    028/**
    029 * Configuration converter. Helper class to convert between Configuration, ExtendedProperties and standard Properties.
    030 *
    031 */
    032public final class ConfigurationConverter {
    033    /** Constant for the default separator for properties with multiple values. */
    034    private static final char DEFAULT_SEPARATOR = ',';
    035
    036    /**
    037     * Private constructor prevents instances from being created.
    038     */
    039    private ConfigurationConverter() {
    040        // to prevent instanciation...
    041    }
    042
    043    /**
    044     * Convert a standard Properties class into a configuration class.
    045     *
    046     * @param props properties object to convert
    047     * @return Configuration configuration created from the Properties
    048     */
    049    public static Configuration getConfiguration(final Properties props) {
    050        return new MapConfiguration(props);
    051    }
    052
    053    /**
    054     * Convert a Configuration class into a Properties class. List properties are joined into a string using either the list
    055     * delimiter handler of the configuration (if it extends AbstractConfiguration) or with a comma as delimiter otherwise.
    056     *
    057     * @param config ImmutableConfiguration object to convert
    058     * @return Properties created from the Configuration
    059     * @since 2.2
    060     */
    061    public static Properties getProperties(final ImmutableConfiguration config) {
    062        final Properties props = new Properties();
    063        final ListDelimiterHandler listHandler;
    064        boolean useDelimiterHandler;
    065
    066        if (config instanceof AbstractConfiguration) {
    067            listHandler = ((AbstractConfiguration) config).getListDelimiterHandler();
    068            useDelimiterHandler = true;
    069        } else {
    070            listHandler = null;
    071            useDelimiterHandler = false;
    072        }
    073
    074        for (final Iterator<String> keys = config.getKeys(); keys.hasNext();) {
    075            final String key = keys.next();
    076            final List<Object> list = config.getList(key);
    077
    078            String propValue;
    079            if (useDelimiterHandler) {
    080                try {
    081                    propValue = String.valueOf(listHandler.escapeList(list, ListDelimiterHandler.NOOP_TRANSFORMER));
    082                } catch (final Exception ex) {
    083                    // obviously, the list handler does not support splitting
    084                    useDelimiterHandler = false;
    085                    propValue = listToString(list);
    086                }
    087            } else {
    088                propValue = listToString(list);
    089            }
    090
    091            props.setProperty(key, propValue);
    092        }
    093
    094        return props;
    095    }
    096
    097    /**
    098     * Convert a Configuration class into a Properties class. List properties are joined into a string using either the list
    099     * delimiter handler of the configuration (if it extends AbstractConfiguration) or with a comma as delimiter otherwise.
    100     * This version of the method exists only for backwards compatibility reason.
    101     *
    102     * @param config Configuration object to convert
    103     * @return Properties created from the Configuration
    104     */
    105    public static Properties getProperties(final Configuration config) {
    106        return getProperties((ImmutableConfiguration) config);
    107    }
    108
    109    /**
    110     * Convert a Configuration class into a Map class.
    111     *
    112     * @param config Configuration object to convert
    113     * @return Map created from the Configuration
    114     */
    115    public static Map<Object, Object> getMap(final Configuration config) {
    116        return new ConfigurationMap(config);
    117    }
    118
    119    /**
    120     * Helper method for joining all elements of a list to a string using the default value separator.
    121     *
    122     * @param list the list
    123     * @return the resulting string
    124     */
    125    private static String listToString(final List<?> list) {
    126        return StringUtils.join(list, DEFAULT_SEPARATOR);
    127    }
    128}