| // *************************************************************************************************************************** |
| // * 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>Cache-Control</l> HTTP request header. |
| * |
| * <p> |
| * Used to specify directives that must be obeyed by all caching mechanisms along the request-response chain. |
| * |
| * <h5 class='figure'>Example</h5> |
| * <p class='bcode w800'> |
| * Cache-Control: no-cache |
| * </p> |
| * |
| * <h5 class='topic'>RFC2616 Specification</h5> |
| * |
| * The Cache-Control general-header field is used to specify directives that MUST be obeyed by all caching mechanisms |
| * along the request/response chain. |
| * The directives specify behavior intended to prevent caches from adversely interfering with the request or response. |
| * These directives typically override the default caching algorithms. |
| * Cache directives are unidirectional in that the presence of a directive in a request does not imply that the same |
| * directive is to be given in the response. |
| * |
| * <p> |
| * Note that HTTP/1.0 caches might not implement Cache-Control and might only implement Pragma: no-cache (see section |
| * 14.32). |
| * |
| * <p> |
| * Cache directives MUST be passed through by a proxy or gateway application, regardless of their significance to that |
| * application, since the directives might be applicable to all recipients along the request/response chain. |
| * It is not possible to specify a cache- directive for a specific cache. |
| * |
| * <p class='bcode w800'> |
| * Cache-Control = "Cache-Control" ":" 1#cache-directive |
| * cache-directive = cache-request-directive |
| * | cache-response-directive |
| * cache-request-directive = |
| * "no-cache" ; Section 14.9.1 |
| * | "no-store" ; Section 14.9.2 |
| * | "max-age" "=" delta-seconds ; Section 14.9.3, 14.9.4 |
| * | "max-stale" [ "=" delta-seconds ] ; Section 14.9.3 |
| * | "min-fresh" "=" delta-seconds ; Section 14.9.3 |
| * | "no-transform" ; Section 14.9.5 |
| * | "only-if-cached" ; Section 14.9.4 |
| * | cache-extension ; Section 14.9.6 |
| * cache-response-directive = |
| * "public" ; Section 14.9.1 |
| * | "private" [ "=" <"> 1#field-name <"> ] ; Section 14.9.1 |
| * | "no-cache" [ "=" <"> 1#field-name <"> ]; Section 14.9.1 |
| * | "no-store" ; Section 14.9.2 |
| * | "no-transform" ; Section 14.9.5 |
| * | "must-revalidate" ; Section 14.9.4 |
| * | "proxy-revalidate" ; Section 14.9.4 |
| * | "max-age" "=" delta-seconds ; Section 14.9.3 |
| * | "s-maxage" "=" delta-seconds ; Section 14.9.3 |
| * | cache-extension ; Section 14.9.6 |
| * cache-extension = token [ "=" ( token | quoted-string ) ] |
| * </p> |
| * |
| * <p> |
| * When a directive appears without any 1#field-name parameter, the directive applies to the entire request or response. |
| * When such a directive appears with a 1#field-name parameter, it applies only to the named field or fields, and not |
| * to the rest of the request or response. This mechanism supports extensibility; implementations of future versions |
| * of the HTTP protocol might apply these directives to header fields not defined in HTTP/1.1. |
| * |
| * <p> |
| * The cache-control directives can be broken down into these general categories: |
| * <ul> |
| * <li>Restrictions on what are cacheable; these may only be imposed by the origin server. |
| * <li>Restrictions on what may be stored by a cache; these may be imposed by either the origin server or the user |
| * agent. |
| * <li>Modifications of the basic expiration mechanism; these may be imposed by either the origin server or the |
| * user agent. |
| * <li>Controls over cache revalidation and reload; these may only be imposed by a user agent. |
| * <li>Control over transformation of entities. |
| * <li>Extensions to the caching system. |
| * </ul> |
| * |
| * <ul class='seealso'> |
| * <li class='extlink'>{@doc RFC2616} |
| * </ul> |
| */ |
| @Header("Cache-Control") |
| public final class CacheControl extends HeaderString { |
| |
| /** |
| * Returns a parsed <c>Cache-Control</c> header. |
| * |
| * @param value The <c>Cache-Control</c> header string. |
| * @return The parsed <c>Cache-Control</c> header, or <jk>null</jk> if the string was null. |
| */ |
| public static CacheControl forString(String value) { |
| if (value == null) |
| return null; |
| return new CacheControl(value); |
| } |
| |
| private CacheControl(String value) { |
| super(value); |
| } |
| } |
