001    // Copyright 2007, 2008 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.internal.services;
016    
017    import org.apache.tapestry5.Asset;
018    import org.apache.tapestry5.annotations.Path;
019    import org.apache.tapestry5.ioc.AnnotationProvider;
020    import org.apache.tapestry5.ioc.ObjectLocator;
021    import org.apache.tapestry5.ioc.ObjectProvider;
022    import org.apache.tapestry5.ioc.services.Builtin;
023    import org.apache.tapestry5.ioc.services.SymbolSource;
024    import org.apache.tapestry5.ioc.services.TypeCoercer;
025    import org.apache.tapestry5.services.AssetSource;
026    import org.apache.tapestry5.services.Core;
027    
028    /**
029     * Exposes assets (in the current locale). The Inject annotation must be supplemented by a {@link Path} annotation, to
030     * identify what asset to be injected.
031     */
032    public class AssetObjectProvider implements ObjectProvider
033    {
034        private final AssetSource source;
035    
036        private final TypeCoercer typeCoercer;
037    
038        private final SymbolSource symbolSource;
039    
040        public AssetObjectProvider(@Core AssetSource source,
041    
042                                   @Builtin TypeCoercer typeCoercer,
043    
044                                   @Builtin SymbolSource symbolSource)
045        {
046            this.source = source;
047            this.typeCoercer = typeCoercer;
048            this.symbolSource = symbolSource;
049        }
050    
051        /**
052         * Provides the asset. If the expression does not identify an asset domain, with a prefix, it is assumed to be a
053         * path on the classpath, relative to the root of the classpath.
054         *
055         * @param objectType the type of object (which must be Object or Asset)
056         * @param locator    not used
057         */
058        public <T> T provide(Class<T> objectType, AnnotationProvider annotationProvider, ObjectLocator locator)
059        {
060            Path path = annotationProvider.getAnnotation(Path.class);
061    
062            if (path == null) return null;
063    
064            String expanded = symbolSource.expandSymbols(path.value());
065    
066            Asset asset = source.getAsset(null, expanded, null);
067    
068            return typeCoercer.coerce(asset, objectType);
069        }
070    }