| // *************************************************************************************************************************** |
| // * Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements. See the NOTICE file * |
| // * distributed with this work for additional information regarding copyright ownership. The ASF licenses this file * |
| // * to you under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance * |
| // * with the License. You may obtain a copy of the License at * |
| // * * |
| // * http://www.apache.org/licenses/LICENSE-2.0 * |
| // * * |
| // * Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an * |
| // * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the * |
| // * specific language governing permissions and limitations under the License. * |
| // *************************************************************************************************************************** |
| package org.apache.juneau.http; |
| |
| import org.apache.juneau.http.annotation.*; |
| |
| /** |
| * Represents a parsed <l>Expires</l> HTTP response header. |
| * |
| * <p> |
| * Gives the date/time after which the response is considered stale (in "HTTP-date" format as defined by RFC 7231). |
| * |
| * <h5 class='figure'>Example</h5> |
| * <p class='bcode w800'> |
| * Expires: Thu, 01 Dec 1994 16:00:00 GMT |
| * </p> |
| * |
| * <h5 class='topic'>RFC2616 Specification</h5> |
| * |
| * The Expires entity-header field gives the date/time after which the response is considered stale. |
| * A stale cache entry may not normally be returned by a cache (either a proxy cache or a user agent cache) unless it is |
| * first validated with the origin server |
| * (or with an intermediate cache that has a fresh copy of the entity). |
| * See section 13.2 for further discussion of the expiration model. |
| * |
| * <p> |
| * The presence of an Expires field does not imply that the original resource will change or cease to exist at, before, |
| * or after that time. |
| * |
| * <p> |
| * The format is an absolute date and time as defined by HTTP-date in section 3.3.1; it MUST be in RFC 1123 date format: |
| * |
| * <p class='bcode w800'> |
| * Expires = "Expires" ":" HTTP-date |
| * </p> |
| * |
| * <p> |
| * An example of its use is... |
| * <p class='bcode w800'> |
| * Expires: Thu, 01 Dec 1994 16:00:00 GMT |
| * </p> |
| * |
| * <p> |
| * Note: if a response includes a Cache-Control field with the max-age directive (see section 14.9.3), that directive |
| * overrides the Expires field. |
| * |
| * <p> |
| * HTTP/1.1 clients and caches MUST treat other invalid date formats, especially including the value "0", as in the past |
| * (i.e., "already expired"). |
| * |
| * <p> |
| * To mark a response as "already expired," an origin server sends an Expires date that is equal to the Date header |
| * value. |
| * (See the rules for expiration calculations in section 13.2.4.) |
| * |
| * <p> |
| * To mark a response as "never expires," an origin server sends an Expires date approximately one year from the time |
| * the response is sent. |
| * HTTP/1.1 servers SHOULD NOT send Expires dates more than one year in the future. |
| * |
| * <p> |
| * The presence of an Expires header field with a date value of some time in the future on a response that otherwise |
| * would by default be non-cacheable indicates that the response is cacheable, unless indicated otherwise by a |
| * Cache-Control header field (section 14.9). |
| * |
| * <ul class='seealso'> |
| * <li class='extlink'>{@doc RFC2616} |
| * </ul> |
| */ |
| @Header("Expires") |
| public final class Expires extends HeaderDate { |
| |
| /** |
| * Returns a parsed <c>Expires</c> header. |
| * |
| * @param value The <c>Expires</c> header string. |
| * @return The parsed <c>Expires</c> header, or <jk>null</jk> if the string was null. |
| */ |
| public static Expires forString(String value) { |
| if (value == null) |
| return null; |
| return new Expires(value); |
| } |
| |
| private Expires(String value) { |
| super(value); |
| } |
| } |