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