1 /* 2 * Copyright (C) 2009 The JSR-330 Expert Group 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package javax.inject; 18 19 import java.lang.annotation.Target; 20 import java.lang.annotation.Retention; 21 import java.lang.annotation.Documented; 22 import static java.lang.annotation.RetentionPolicy.RUNTIME; 23 import static java.lang.annotation.ElementType.ANNOTATION_TYPE; 24 25 /** 26 * Identifies qualifier annotations. Anyone can define a new qualifier. A 27 * qualifier annotation: 28 * 29 * <ul> 30 * <li>is annotated with {@code @Qualifier}, {@code @Retention(RUNTIME)}, 31 * and typically {@code @Documented}.</li> 32 * <li>can have attributes.</li> 33 * <li>may be part of the public API, much like the dependency type, but 34 * unlike implementation types which needn't be part of the public 35 * API.</li> 36 * <li>may have restricted usage if annotated with {@code @Target}. While 37 * this specification covers applying qualifiers to fields and 38 * parameters only, some injector configurations might use qualifier 39 * annotations in other places (on methods or classes for example).</li> 40 * </ul> 41 * 42 * <p>For example: 43 * 44 * <pre> 45 * @java.lang.annotation.Documented 46 * @java.lang.annotation.Retention(RUNTIME) 47 * @javax.inject.Qualifier 48 * public @interface Leather { 49 * Color color() default Color.TAN; 50 * public enum Color { RED, BLACK, TAN } 51 * }</pre> 52 * 53 * @see javax.inject.Named @Named 54 */ 55 @Target(ANNOTATION_TYPE) 56 @Retention(RUNTIME) 57 @Documented 58 public @interface Qualifier {} 59