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
015package org.apache.tapestry5.internal.services;
016
017import org.apache.tapestry5.Asset;
018import org.apache.tapestry5.annotations.Path;
019import org.apache.tapestry5.commons.AnnotationProvider;
020import org.apache.tapestry5.commons.ObjectLocator;
021import org.apache.tapestry5.commons.ObjectProvider;
022import org.apache.tapestry5.commons.services.TypeCoercer;
023import org.apache.tapestry5.ioc.services.Builtin;
024import org.apache.tapestry5.ioc.services.SymbolSource;
025import org.apache.tapestry5.services.AssetSource;
026import 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 */
032public 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}