001    // Copyright 2007, 2008, 2010, 2011 The Apache Software Foundation
002    //
003    // Licensed under the Apache License, Version 2.0 (the "License");
004    // you may not use this file except in compliance with the License.
005    // You may obtain a copy of the License at
006    //
007    // http://www.apache.org/licenses/LICENSE-2.0
008    //
009    // Unless required by applicable law or agreed to in writing, software
010    // distributed under the License is distributed on an "AS IS" BASIS,
011    // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
012    // See the License for the specific language governing permissions and
013    // limitations under the License.
014    
015    package org.apache.tapestry5.util;
016    
017    import org.apache.tapestry5.ValueEncoder;
018    import org.apache.tapestry5.ioc.internal.util.InternalUtils;
019    import org.apache.tapestry5.ioc.services.TypeCoercer;
020    
021    /**
022     * A value encoder that can be used for arbitrary Enum types. The enum name is stored as the client side value.
023     */
024    public class EnumValueEncoder<E extends Enum<E>> implements ValueEncoder<E>
025    {
026        private final TypeCoercer typeCoercer;
027    
028        private final Class<E> enumType;
029    
030        public EnumValueEncoder(TypeCoercer typeCoercer, final Class<E> enumType)
031        {
032            assert enumType != null;
033    
034            this.typeCoercer = typeCoercer;
035            this.enumType = enumType;
036        }
037    
038        public String toClient(E value)
039        {
040            if (value == null)
041                return null;
042    
043            return value.name();
044        }
045    
046        public E toValue(String clientValue)
047        {
048            if (InternalUtils.isBlank(clientValue))
049                return null;
050    
051            return typeCoercer.coerce(clientValue, enumType);
052        }
053    
054    }