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.http.header;
014
015import java.time.*;
016import java.util.function.*;
017
018import org.apache.juneau.http.annotation.*;
019
020/**
021 * Represents a parsed <l>If-Unmodified-Since</l> HTTP request header.
022 *
023 * <p>
024 * Only send the response if the entity has not been modified since a specific time.
025 *
026 * <h5 class='figure'>Example</h5>
027 * <p class='bcode'>
028 *    If-Unmodified-Since: Sat, 29 Oct 1994 19:43:31 GMT
029 * </p>
030 *
031 * <h5 class='topic'>RFC2616 Specification</h5>
032 *
033 * The If-Unmodified-Since request-header field is used with a method to make it conditional.
034 * If the requested resource has not been modified since the time specified in this field, the server SHOULD perform the
035 * requested operation as if the If-Unmodified-Since header were not present.
036 *
037 * <p>
038 * If the requested variant has been modified since the specified time, the server MUST NOT perform the requested
039 * operation, and MUST return a 412 (Precondition Failed).
040 *
041 * <p class='bcode'>
042 *    If-Unmodified-Since = "If-Unmodified-Since" ":" HTTP-date
043 * </p>
044 *
045 * <p>
046 * An example of the field is:
047 * <p class='bcode'>
048 *    If-Unmodified-Since: Sat, 29 Oct 1994 19:43:31 GMT
049 * </p>
050 *
051 * <p>
052 * If the request normally (i.e., without the If-Unmodified-Since header) would result in anything other than a 2xx or
053 * 412 status, the If-Unmodified-Since header SHOULD be ignored.
054 *
055 * <p>
056 * If the specified date is invalid, the header is ignored.
057 *
058 * <p>
059 * The result of a request having both an If-Unmodified-Since header field and either an If-None-Match or an
060 * If-Modified-Since header fields is undefined by this specification.
061 *
062 * <h5 class='section'>See Also:</h5><ul>
063 *    <li class='link'><a class="doclink" href="../../../../../index.html#juneau-rest-common">juneau-rest-common</a>
064 *    <li class='extlink'><a class="doclink" href="https://www.w3.org/Protocols/rfc2616/rfc2616.html">Hypertext Transfer Protocol -- HTTP/1.1</a>
065 * </ul>
066 *
067 * @serial exclude
068 */
069@Header("If-Unmodified-Since")
070public class IfUnmodifiedSince extends BasicDateHeader {
071
072   //-----------------------------------------------------------------------------------------------------------------
073   // Static
074   //-----------------------------------------------------------------------------------------------------------------
075
076   private static final long serialVersionUID = 1L;
077   private static final String NAME = "If-Unmodified-Since";
078
079   /**
080    * Static creator.
081    *
082    * @param value
083    *    The header value.
084    *    <br>Must be an RFC-1123 formated string (e.g. <js>"Sat, 29 Oct 1994 19:43:31 GMT"</js>).
085    *    <br>Can be <jk>null</jk>.
086    * @return A new header bean, or <jk>null</jk> if the name is <jk>null</jk> or empty or the value is <jk>null</jk>.
087    */
088   public static IfUnmodifiedSince of(String value) {
089      return value == null ? null : new IfUnmodifiedSince(value);
090   }
091
092   /**
093    * Static creator.
094    *
095    * @param value
096    *    The header value.
097    *    <br>Can be <jk>null</jk>.
098    * @return A new header bean, or <jk>null</jk> if the name is <jk>null</jk> or empty or the value is <jk>null</jk>.
099    */
100   public static IfUnmodifiedSince of(ZonedDateTime value) {
101      return value == null ? null : new IfUnmodifiedSince(value);
102   }
103
104   /**
105    * Static creator 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    * @return A new header bean, or <jk>null</jk> if the name is <jk>null</jk> or empty or the value is <jk>null</jk>.
114    */
115   public static IfUnmodifiedSince of(Supplier<ZonedDateTime> value) {
116      return value == null ? null : new IfUnmodifiedSince(value);
117   }
118
119   //-----------------------------------------------------------------------------------------------------------------
120   // Instance
121   //-----------------------------------------------------------------------------------------------------------------
122
123   /**
124    * Constructor.
125    *
126    * @param value
127    *    The header value.
128    *    <br>Must be an RFC-1123 formated string (e.g. <js>"Sat, 29 Oct 1994 19:43:31 GMT"</js>).
129    *    <br>Can be <jk>null</jk>.
130    */
131   public IfUnmodifiedSince(String value) {
132      super(NAME, value);
133   }
134
135   /**
136    * Constructor.
137    *
138    * @param value
139    *    The header value.
140    *    <br>Can be <jk>null</jk>.
141    */
142   public IfUnmodifiedSince(ZonedDateTime value) {
143      super(NAME, value);
144   }
145
146   /**
147    * Constructor with delayed value.
148    *
149    * <p>
150    * Header value is re-evaluated on each call to {@link #getValue()}.
151    *
152    * @param value
153    *    The supplier of the header value.
154    *    <br>Can be <jk>null</jk>.
155    */
156   public IfUnmodifiedSince(Supplier<ZonedDateTime> value) {
157      super(NAME, value);
158   }
159}