001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.apache.juneau.http.header;
018
019import java.util.function.*;
020
021import org.apache.juneau.http.annotation.*;
022
023/**
024 * Represents a parsed <l>User-Agent</l> HTTP request header.
025 *
026 * <p>
027 * The user agent string of the user agent.
028 *
029 * <h5 class='figure'>Example</h5>
030 * <p class='bcode'>
031 *    User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:12.0) Gecko/20100101 Firefox/21.0
032 * </p>
033 *
034 * <h5 class='topic'>RFC2616 Specification</h5>
035 *
036 * The User-Agent request-header field contains information about the user agent originating the request.
037 * This is for statistical purposes, the tracing of protocol violations, and automated recognition of user agents for
038 * the sake of tailoring responses to avoid particular user agent limitations.
039 * User agents SHOULD include this field with requests.
040 * The field can contain multiple product tokens (section 3.8) and comments identifying the agent and any sub-products
041 * which form a significant part of the user agent.
042 * By convention, the product tokens are listed in order of their significance for identifying the application.
043 *
044 * <p class='bcode'>
045 *    User-Agent     = "User-Agent" ":" 1*( product | comment )
046 * </p>
047 *
048 * <p>
049 * Example:
050 * <p class='bcode'>
051 *    User-Agent: CERN-LineMode/2.15 libwww/2.17b3
052 * </p>
053 *
054 * <h5 class='section'>See Also:</h5><ul>
055 *    <li class='link'><a class="doclink" href="https://juneau.apache.org/docs/topics/JuneauRestCommonBasics">juneau-rest-common Basics</a>
056 *    <li class='extlink'><a class="doclink" href="https://www.w3.org/Protocols/rfc2616/rfc2616.html">Hypertext Transfer Protocol -- HTTP/1.1</a>
057 * </ul>
058 *
059 * @serial exclude
060 */
061@Header("User-Agent")
062public class UserAgent extends BasicStringHeader {
063   private static final long serialVersionUID = 1L;
064   private static final String NAME = "User-Agent";
065
066   /**
067    * Static creator.
068    *
069    * @param value
070    *    The header value.
071    *    <br>Can be <jk>null</jk>.
072    * @return A new header bean, or <jk>null</jk> if the value is <jk>null</jk>.
073    */
074   public static UserAgent of(String value) {
075      return value == null ? null : new UserAgent(value);
076   }
077
078   /**
079    * Static creator with delayed value.
080    *
081    * <p>
082    * Header value is re-evaluated on each call to {@link #getValue()}.
083    *
084    * @param value
085    *    The supplier of the header value.
086    *    <br>Can be <jk>null</jk>.
087    * @return A new header bean, or <jk>null</jk> if the value is <jk>null</jk>.
088    */
089   public static UserAgent of(Supplier<String> value) {
090      return value == null ? null : new UserAgent(value);
091   }
092
093   /**
094    * Constructor.
095    *
096    * @param value
097    *    The header value.
098    *    <br>Can be <jk>null</jk>.
099    */
100   public UserAgent(String value) {
101      super(NAME, value);
102   }
103
104   /**
105    * Constructor with delayed value.
106    *
107    * <p>
108    * Header value is re-evaluated on each call to {@link #getValue()}.
109    *
110    * @param value
111    *    The supplier of the header value.
112    *    <br>Can be <jk>null</jk>.
113    */
114   public UserAgent(Supplier<String> value) {
115      super(NAME, value);
116   }
117}