    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}