001// Copyright 2007 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.annotations.Service;
018import org.apache.tapestry5.commons.AnnotationProvider;
019import org.apache.tapestry5.commons.ObjectLocator;
020import org.apache.tapestry5.commons.ObjectProvider;
021
022/**
023 * Adds support for the {@link Service} annotation (which can be applied to fields or parameters), which is used to
024 * disambiguate injection when multiple services implement the same service interface.
025 */
026public class ServiceAnnotationObjectProvider implements ObjectProvider
027{
028    public <T> T provide(Class<T> objectType, AnnotationProvider annotationProvider,
029                         ObjectLocator locator)
030    {
031        Service annotation = annotationProvider.getAnnotation(Service.class);
032
033        if (annotation == null) return null;
034
035        return locator.getService(annotation.value(), objectType);
036    }
037
038}