001// ***************************************************************************************************************************
002// * Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements.  See the NOTICE file *
003// * distributed with this work for additional information regarding copyright ownership.  The ASF licenses this file        *
004// * to you under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance            *
005// * with the License.  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 distributed under the License is distributed on an  *
010// * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the License for the        *
011// * specific language governing permissions and limitations under the License.                                              *
012// ***************************************************************************************************************************
013package org.apache.juneau.rest.annotation;
014
015import static java.lang.annotation.ElementType.*;
016import static java.lang.annotation.RetentionPolicy.*;
017
018import java.lang.annotation.*;
019
020import org.apache.juneau.httppart.*;
021
022/**
023 * Annotation that can be applied to a parameter of a {@link RestMethod @RestMethod} annotated method to identify it as a HTTP
024 * request header converted to a POJO.
025 * 
026 * <h5 class='section'>Example:</h5>
027 * <p class='bcode'>
028 *    <ja>@RestMethod</ja>(name=<jsf>GET</jsf>)
029 *    <jk>public void</jk> doGet(RestRequest req, RestResponse res, <ja>@Header</ja>(<js>"ETag"</js>) UUID etag) {
030 *       ...
031 *    }
032 * </p>
033 * 
034 * <p>
035 * This is functionally equivalent to the following code...
036 * <p class='bcode'>
037 *    <ja>@RestMethod</ja>(name=<jsf>GET</jsf>)
038 *    <jk>public void</jk> doPostPerson(RestRequest req, RestResponse res) {
039 *       UUID etag = req.getHeader(UUID.<jk>class</jk>, "ETag");
040 *       ...
041 *    }
042 * </p>
043 * 
044 * <h5 class='section'>See Also:</h5>
045 * <ul>
046 *    <li class='link'><a class="doclink" href="../../../../../overview-summary.html#juneau-rest-server.Header">Overview &gt; juneau-rest-server &gt; @Header</a>
047 * </ul>
048 */
049@Documented
050@Target(PARAMETER)
051@Retention(RUNTIME)
052@Inherited
053public @interface Header {
054
055   /**
056    * The default value for this header if it's not present in the request.
057    */
058   String def() default "";
059
060   /**
061    * HTTP header name.
062    */
063   String name() default "";
064
065   /**
066    * Specifies the {@link HttpPartParser} class used for parsing values from strings.
067    * 
068    * <p>
069    * The default value for this parser is inherited from the servlet/method which defaults to {@link UonPartParser}.
070    * <br>You can use {@link SimplePartParser} to parse POJOs that are directly convertible from <code>Strings</code>.
071    */
072   Class<? extends HttpPartParser> parser() default HttpPartParser.Null.class;
073
074   /**
075    * A synonym for {@link #name()}.
076    * 
077    * <p>
078    * Allows you to use shortened notation if you're only specifying the name.
079    */
080   String value() default "";
081}