| /* |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you under the Apache License, Version 2.0 (the |
| * "License"); you may not use this file except in compliance |
| * with the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, |
| * software distributed under the License is distributed on an |
| * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY |
| * KIND, either express or implied. See the License for the |
| * specific language governing permissions and limitations |
| * under the License. |
| */ |
| package org.apache.felix.dm.annotation.api; |
| |
| import java.lang.annotation.ElementType; |
| import java.lang.annotation.Retention; |
| import java.lang.annotation.RetentionPolicy; |
| import java.lang.annotation.Target; |
| |
| /** |
| * Annotates a method returning the list of objects which are part of a Component implementation. |
| * When implementing complex Components, you often need to use more than one object instances. |
| * Moreover, several of these instances might want to have dependencies injected, as well as lifecycle |
| * callbacks invoked, like the methods annotated with {@link Init}, {@link Start}, {@link Stop}, |
| * {@link Destroy} annotations. In such cases you can tell the dependency manager which instances to |
| * consider, by annotating a method in your Component, returning a list of objects which are part |
| * of the implementation. |
| * <p> |
| * This annotation may be applied on a method which is part of class annotated with either a {@link Component}, |
| * {@link AspectService}, {@link AdapterService}, {@link FactoryConfigurationAdapterService} or |
| * {@link ResourceAdapterService} annotation. |
| * |
| * <h3>Usage Examples</h3> |
| * |
| * <p> Here, the "MyComponent" component is composed of the Helper class, which is also injected with |
| * service dependencies. The lifecycle callbacks are also invoked in the Helper (if the Helper defines |
| * them):<p> |
| * <blockquote> |
| * <pre> |
| * |
| * class Helper { |
| * LogService logService; // Injected |
| * void start() {} // lifecycle callback |
| * void bind(OtherService otherService) {} // injected |
| * } |
| * |
| * @Component |
| * class MyComponent { |
| * // Helper which will also be injected with our service dependencies |
| * private Helper helper = new Helper(); |
| * |
| * @Composition |
| * Object[] getComposition() { |
| * return new Object[] { this, helper }; |
| * } |
| * |
| * @ServiceDependency |
| * private LogService logService; // Helper.logService will be also be injected, if defined. |
| * |
| * @Start |
| * void start() {} // the Helper.start() method will also be called, if defined |
| * |
| * @ServiceDependency |
| * void bind(OtherService otherService) {} // the Helper.bind() method will also be called, if defined |
| * } |
| * </pre> |
| * </blockquote> |
| * |
| * @author <a href="mailto:dev@felix.apache.org">Felix Project Team</a> |
| */ |
| @Retention(RetentionPolicy.CLASS) |
| @Target(ElementType.METHOD) |
| public @interface Composition |
| { |
| } |