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}