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    }