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 */
017package org.apache.isis.core.commons.lang;
018
019import java.util.Properties;
020
021import com.google.common.base.Joiner;
022
023public class PropertiesExtensions {
024    
025    private PropertiesExtensions(){}
026
027    public static Properties subset(Properties extendee, String... prefix) {
028        final String prefices = Joiner.on(".").join(prefix);
029        return subsetOf(extendee, prefices+".");
030    }
031    
032    private static Properties subsetOf(Properties extendee, String prefix) {
033        final int prefixLength = prefix.length();
034    
035        final Properties subsetProperties = new Properties();
036        for(Object keyObj: extendee.keySet()) {
037            final String key = (String)keyObj;
038            if (key.startsWith(prefix)) {
039                final String keySuffix = key.substring(prefixLength);
040                subsetProperties.put(keySuffix, extendee.get(key));
041            }
042        }
043        return subsetProperties;
044    }
045
046
047}