    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
    015    package org.apache.tapestry5.ioc.annotations;
    016
    017    import java.lang.annotation.Documented;
    018    import static java.lang.annotation.ElementType.*;
    019    import java.lang.annotation.Retention;
    020    import static java.lang.annotation.RetentionPolicy.RUNTIME;
    021    import java.lang.annotation.Target;
    022
    023    import 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 })
    058    public @interface Inject
    059    {
    060
    061    }