001    /*
002      GRANITE DATA SERVICES
003      Copyright (C) 2011 GRANITE DATA SERVICES S.A.S.
004    
005      This file is part of Granite Data Services.
006    
007      Granite Data Services is free software; you can redistribute it and/or modify
008      it under the terms of the GNU Library General Public License as published by
009      the Free Software Foundation; either version 2 of the License, or (at your
010      option) any later version.
011    
012      Granite Data Services is distributed in the hope that it will be useful, but
013      WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
014      FITNESS FOR A PARTICULAR PURPOSE. See the GNU Library General Public License
015      for more details.
016    
017      You should have received a copy of the GNU Library General Public License
018      along with this library; if not, see <http://www.gnu.org/licenses/>.
019    */
020    
021    package org.granite.util;
022    
023    import java.lang.reflect.ParameterizedType;
024    import java.lang.reflect.Type;
025    import java.lang.reflect.WildcardType;
026    import java.util.HashMap;
027    import java.util.Map;
028    import java.util.SortedMap;
029    import java.util.TreeMap;
030    
031    /**
032     * @author Franck WOLFF
033     */
034    public class MapUtil {
035    
036        public static Type[] getComponentTypes(Type mapType) {
037            final Class<?> mapClass = ClassUtil.classOfType(mapType);
038    
039            if (!Map.class.isAssignableFrom(mapClass))
040                return null;
041    
042            Type[] componentTypes = new Type[] {
043                WildcardType.class,
044                WildcardType.class
045            };
046    
047            if (mapType instanceof ParameterizedType) {
048                Type[] argTypes = ((ParameterizedType)mapType).getActualTypeArguments();
049                if (argTypes != null) {
050                    if (argTypes.length > 0)
051                        componentTypes[0] = argTypes[0];
052                    if (argTypes.length > 1)
053                        componentTypes[1] = argTypes[1];
054                }
055            }
056    
057            return componentTypes;
058        }
059    
060        @SuppressWarnings("unchecked")
061        public static Map<Object, Object> newMap(Class<?> targetClass, int length)
062            throws InstantiationException, IllegalAccessException  {
063    
064            if (targetClass.isInterface()) {
065    
066                if (SortedMap.class.isAssignableFrom(targetClass))
067                    return new TreeMap<Object, Object>();
068    
069                if (targetClass.isAssignableFrom(HashMap.class))
070                    return new HashMap<Object, Object>(length);
071    
072                throw new IllegalArgumentException("Unsupported collection interface: " + targetClass);
073            }
074    
075            return (Map<Object, Object>)targetClass.newInstance();
076        }
077    }