001// ***************************************************************************************************************************
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006// *                                                                                                                         *
007// *  http://www.apache.org/licenses/LICENSE-2.0                                                                             *
008// *                                                                                                                         *
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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>Last-Modified</l> HTTP response header.
022 *
023 * <p>
024 * The last modified date for the requested object (in "HTTP-date" format as defined by RFC 7231).
025 *
026 * <h5 class='figure'>Example</h5>
027 * <p class='bcode'>
028 *    Last-Modified: Tue, 15 Nov 1994 12:45:26 GMT
029 * </p>
030 *
031 * <h5 class='topic'>RFC2616 Specification</h5>
032 *
033 * The Last-Modified entity-header field indicates the date and time at which the origin server believes the variant was
034 * last modified.
035 *
036 * <p class='bcode'>
037 *    Last-Modified  = "Last-Modified" ":" HTTP-date
038 * </p>
039 *
040 * <p>
041 * An example of its use is...
042 * <p class='bcode'>
043 *    Last-Modified: Tue, 15 Nov 1994 12:45:26 GMT
044 * </p>
045 *
046 * <p>
047 * The exact meaning of this header field depends on the implementation of the origin server and the nature of the
048 * original resource.
049 * For files, it may be just the file system last-modified time.
050 * For entities with dynamically included parts, it may be the most recent of the set of last-modify times for its
051 * component parts.
052 * For database gateways, it may be the last-update time stamp of the record.
053 * For virtual objects, it may be the last time the internal state changed.
054 *
055 * <p>
056 * An origin server MUST NOT send a Last-Modified date which is later than the server's time of message origination.
057 * In such cases, where the resource's last modification would indicate some time in the future, the server MUST replace
058 * that date with the message origination date.
059 *
060 * <p>
061 * An origin server SHOULD obtain the Last-Modified value of the entity as close as possible to the time that it
062 * generates the Date value of its response.
063 * This allows a recipient to make an accurate assessment of the entity's modification time, especially if the entity
064 * changes near the time that the response is generated.
065 *
066 * <p>
067 * HTTP/1.1 servers SHOULD send Last-Modified whenever feasible.
068 *
069 * <h5 class='section'>See Also:</h5><ul>
070 *    <li class='link'><a class="doclink" href="../../../../../index.html#juneau-rest-common">juneau-rest-common</a>
071 *    <li class='extlink'><a class="doclink" href="https://www.w3.org/Protocols/rfc2616/rfc2616.html">Hypertext Transfer Protocol -- HTTP/1.1</a>
072 * </ul>
073 *
074 * @serial exclude
075 */
076@Header("Last-Modified")
077public class LastModified extends BasicDateHeader {
078
079   //-----------------------------------------------------------------------------------------------------------------
080   // Static
081   //-----------------------------------------------------------------------------------------------------------------
082
083   private static final long serialVersionUID = 1L;
084   private static final String NAME = "Last-Modified";
085
086   /**
087    * Static creator.
088    *
089    * @param value
090    *    The header value.
091    *    <br>Must be an RFC-1123 formated string (e.g. <js>"Sat, 29 Oct 1994 19:43:31 GMT"</js>).
092    *    <br>Can be <jk>null</jk>.
093    * @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>.
094    */
095   public static LastModified of(String value) {
096      return value == null ? null : new LastModified(value);
097   }
098
099   /**
100    * Static creator.
101    *
102    * @param value
103    *    The header value.
104    *    <br>Can be <jk>null</jk>.
105    * @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>.
106    */
107   public static LastModified of(ZonedDateTime value) {
108      return value == null ? null : new LastModified(value);
109   }
110
111   /**
112    * Static creator with delayed value.
113    *
114    * <p>
115    * Header value is re-evaluated on each call to {@link #getValue()}.
116    *
117    * @param value
118    *    The supplier of the header value.
119    *    <br>Can be <jk>null</jk>.
120    * @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>.
121    */
122   public static LastModified of(Supplier<ZonedDateTime> value) {
123      return value == null ? null : new LastModified(value);
124   }
125
126   //-----------------------------------------------------------------------------------------------------------------
127   // Instance
128   //-----------------------------------------------------------------------------------------------------------------
129
130   /**
131    * Constructor.
132    *
133    * @param value
134    *    The header value.
135    *    <br>Must be an RFC-1123 formated string (e.g. <js>"Sat, 29 Oct 1994 19:43:31 GMT"</js>).
136    *    <br>Can be <jk>null</jk>.
137    */
138   public LastModified(String value) {
139      super(NAME, value);
140   }
141
142   /**
143    * Constructor.
144    *
145    * @param value
146    *    The header value.
147    *    <br>Can be <jk>null</jk>.
148    */
149   public LastModified(ZonedDateTime value) {
150      super(NAME, value);
151   }
152
153   /**
154    * Constructor with delayed value.
155    *
156    * <p>
157    * Header value is re-evaluated on each call to {@link #getValue()}.
158    *
159    * @param value
160    *    The supplier of the header value.
161    *    <br>Can be <jk>null</jk>.
162    */
163   public LastModified(Supplier<ZonedDateTime> value) {
164      super(NAME, value);
165   }
166}