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; 014 015import org.apache.juneau.http.annotation.*; 016 017/** 018 * Represents a parsed <l>Last-Modified</l> HTTP response header. 019 * 020 * <p> 021 * The last modified date for the requested object (in "HTTP-date" format as defined by RFC 7231). 022 * 023 * <h5 class='figure'>Example</h5> 024 * <p class='bcode w800'> 025 * Last-Modified: Tue, 15 Nov 1994 12:45:26 GMT 026 * </p> 027 * 028 * <h5 class='topic'>RFC2616 Specification</h5> 029 * 030 * The Last-Modified entity-header field indicates the date and time at which the origin server believes the variant was 031 * last modified. 032 * 033 * <p class='bcode w800'> 034 * Last-Modified = "Last-Modified" ":" HTTP-date 035 * </p> 036 * 037 * <p> 038 * An example of its use is... 039 * <p class='bcode w800'> 040 * Last-Modified: Tue, 15 Nov 1994 12:45:26 GMT 041 * </p> 042 * 043 * <p> 044 * The exact meaning of this header field depends on the implementation of the origin server and the nature of the 045 * original resource. 046 * For files, it may be just the file system last-modified time. 047 * For entities with dynamically included parts, it may be the most recent of the set of last-modify times for its 048 * component parts. 049 * For database gateways, it may be the last-update time stamp of the record. 050 * For virtual objects, it may be the last time the internal state changed. 051 * 052 * <p> 053 * An origin server MUST NOT send a Last-Modified date which is later than the server's time of message origination. 054 * In such cases, where the resource's last modification would indicate some time in the future, the server MUST replace 055 * that date with the message origination date. 056 * 057 * <p> 058 * An origin server SHOULD obtain the Last-Modified value of the entity as close as possible to the time that it 059 * generates the Date value of its response. 060 * This allows a recipient to make an accurate assessment of the entity's modification time, especially if the entity 061 * changes near the time that the response is generated. 062 * 063 * <p> 064 * HTTP/1.1 servers SHOULD send Last-Modified whenever feasible. 065 * 066 * <ul class='seealso'> 067 * <li class='extlink'>{@doc RFC2616} 068 * </ul> 069 */ 070@Header("Last-Modified") 071public final class LastModified extends HeaderDate { 072 073 /** 074 * Returns a parsed <c>Last-Modified</c> header. 075 * 076 * @param value The <c>Last-Modified</c> header string. 077 * @return The parsed <c>Last-Modified</c> header, or <jk>null</jk> if the string was null. 078 */ 079 public static LastModified forString(String value) { 080 if (value == null) 081 return null; 082 return new LastModified(value); 083 } 084 085 private LastModified(String value) { 086 super(value); 087 } 088}