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