001// Copyright 2006, 2007, 2008, 2009, 2010 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.ioc.annotations;
016
017import java.lang.annotation.Documented;
018import static java.lang.annotation.ElementType.*;
019import java.lang.annotation.Retention;
020import static java.lang.annotation.RetentionPolicy.RUNTIME;
021import java.lang.annotation.Target;
022
023import static org.apache.tapestry5.ioc.annotations.AnnotationUseContext.*;
024
025/**
026 * This annotation serves is something of the Swiss Army knife for operations related to injection of dependencies into
027 * an arbitrary method of Java Bean.
028 * <p/>
029 * <p>
030 * It marks parameters that should be injected in the IoC container, and it marks fields that should be injected inside
031 * Tapestry components.
032 * <p/>
033 * In terms of the IoC container; normally, resources take precedence over annotations when injecting. The Inject
034 * annotation overrides this default, forcing the resolution of the parameters value via the master
035 * {@link org.apache.tapestry5.ioc.ObjectProvider}, even when the parameter's type matches a type that is normally a
036 * resource.
037 * <p/>
038 * For service implementations, module classes, and other objects constructed via
039 * {@link org.apache.tapestry5.ioc.ObjectLocator#autobuild(Class)}, this annotation indicates that an injection is
040 * desired on the field, as with fields of a Tapestry component.
041 * <p/>
042 * In terms of the IoC container, the Inject annotation is only used on parameters to service builder methods (and
043 * contributor and decorator methods) and on module class constructors. constructors. However, inside Tapestry
044 * components (<em>and only inside components</em>), it may be applied to fields. On fields that require injection, the
045 * Inject annotation is <em>required</em>.
046 * <p/>
047 * Finally, on a constructor, this is used to indicate <em>which</em> constructor should be used when more than one is
048 * available.
049 * 
050 * @see org.apache.tapestry5.ioc.ObjectProvider
051 */
052@Target(
053{ PARAMETER, FIELD, CONSTRUCTOR })
054@Retention(RUNTIME)
055@Documented
056@UseWith(
057{ COMPONENT, MIXIN, PAGE, SERVICE })
058public @interface Inject
059{
060
061}