001    // Copyright 2010 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.services.meta;
016    
017    import java.lang.annotation.Annotation;
018    
019    import org.apache.tapestry5.ioc.internal.util.InternalUtils;
020    import org.apache.tapestry5.model.MutableComponentModel;
021    
022    /**
023     * Implementation of {@link MetaDataExtractor} that is used to set a fixed
024     * value for a fixed meta-data key, when a given annotation is present.
025     * 
026     * @since 5.2.0
027     */
028    public class FixedExtractor<T extends Annotation> implements MetaDataExtractor<T>
029    {
030        private final String key;
031    
032        private final String value;
033    
034        /** Defaults the value to "true". */
035        public FixedExtractor(String key)
036        {
037            this(key, "true");
038        }
039    
040        public FixedExtractor(String key, String value)
041        {
042            assert InternalUtils.isNonBlank(key);
043            this.key = key;
044            assert InternalUtils.isNonBlank(value);
045            this.value = value;
046        }
047    
048        public void extractMetaData(MutableComponentModel model, T annotation)
049        {
050            model.setMeta(key, value);
051        }
052    
053    }