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    
015    package org.apache.tapestry5.internal.services;
016    
017    import org.apache.tapestry5.annotations.Service;
018    import org.apache.tapestry5.ioc.AnnotationProvider;
019    import org.apache.tapestry5.ioc.ObjectLocator;
020    import org.apache.tapestry5.ioc.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     */
026    public 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    }