    001// Licensed under the Apache License, Version 2.0 (the "License");
    002// you may not use this file except in compliance with the License.
    003// You may obtain a copy of the License at
    004//
    005// http://www.apache.org/licenses/LICENSE-2.0
    006//
    007// Unless required by applicable law or agreed to in writing, software
    008// distributed under the License is distributed on an "AS IS" BASIS,
    009// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    010// See the License for the specific language governing permissions and
    011// limitations under the License.
    012
    013package org.apache.tapestry5.ioc.annotations;
    014
    015import java.lang.annotation.Documented;
    016import java.lang.annotation.Retention;
    017import java.lang.annotation.Target;
    018
    019import static java.lang.annotation.ElementType.*;
    020import static java.lang.annotation.RetentionPolicy.RUNTIME;
    021import static org.apache.tapestry5.ioc.annotations.AnnotationUseContext.*;
    022
    023/**
    024 * This annotation serves is something of the Swiss Army knife for operations related to injection of dependencies into
    025 * an arbitrary method of Java Bean.
    026 *
    027 *
    028 * It marks parameters that should be injected in the IoC container, and it marks fields that should be injected inside
    029 * Tapestry components.
    030 *
    031 * In terms of the IoC container; normally, resources take precedence over annotations when injecting. The Inject
    032 * annotation overrides this default, forcing the resolution of the parameters value via the master
    033 * <a href="https://tapestry.apache.org/current/apidocs/org/apache/tapestry5/commons/ObjectProvider.html">ObjectProvider</a>, even when the parameter's type matches a type that is normally a
    034 * resource.
    035 *
    036 * For service implementations, module classes, and other objects constructed via
    037 * <a href="https://tapestry.apache.org/current/apidocs/org/apache/tapestry5/commons/ObjectLocator.html#autobuild(Class)">ObjectLocator#autobuild(Class)</a>, this annotation indicates that an injection is
    038 * desired on the field, as with fields of a Tapestry component.
    039 *
    040 * In terms of the IoC container, the Inject annotation is only used on parameters to service builder methods (and
    041 * contributor and decorator methods) and on module class constructors. constructors. However, inside Tapestry
    042 * components (<em>and only inside components</em>), it may be applied to fields. On fields that require injection, the
    043 * Inject annotation is <em>required</em>.
    044 *
    045 * Finally, on a constructor, this is used to indicate <em>which</em> constructor should be used when more than one is
    046 * available.
    047 *
    048 * @see org.apache.tapestry5.commons.ObjectProvider
    049 */
    050@Target(
    051{ PARAMETER, FIELD, CONSTRUCTOR })
    052@Retention(RUNTIME)
    053@Documented
    054@UseWith(
    055{ COMPONENT, MIXIN, PAGE, SERVICE })
    056public @interface Inject
    057{
    058
    059}