| // *************************************************************************************************************************** |
| // * 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>Pragma</l> HTTP request/response header. |
| * |
| * <p> |
| * Implementation-specific fields that may have various effects anywhere along the request-response chain. |
| * |
| * <h5 class='figure'>Example</h5> |
| * <p class='bcode w800'> |
| * Pragma: no-cache |
| * </p> |
| * |
| * <h5 class='topic'>RFC2616 Specification</h5> |
| * |
| * The Pragma general-header field is used to include implementation- specific directives that might apply to any |
| * recipient along the request/response chain. |
| * All pragma directives specify optional behavior from the viewpoint of the protocol; however, some systems MAY |
| * require that behavior be consistent with the directives. |
| * |
| * <p class='bcode w800'> |
| * Pragma = "Pragma" ":" 1#pragma-directive |
| * pragma-directive = "no-cache" | extension-pragma |
| * extension-pragma = token [ "=" ( token | quoted-string ) ] |
| * </p> |
| * |
| * <p> |
| * When the no-cache directive is present in a request message, an application SHOULD forward the request toward the |
| * origin server even if it has a cached copy of what is being requested. |
| * This pragma directive has the same semantics as the no-cache cache-directive (see section 14.9) and is defined here |
| * for backward compatibility with HTTP/1.0. |
| * Clients SHOULD include both header fields when a no-cache request is sent to a server not known to be HTTP/1.1 |
| * compliant. |
| * |
| * <p> |
| * Pragma 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 pragma for a specific recipient; however, any pragma directive not relevant to a |
| * recipient SHOULD be ignored by that recipient. |
| * |
| * <p> |
| * HTTP/1.1 caches SHOULD treat "Pragma: no-cache" as if the client had sent "Cache-Control: no-cache". |
| * No new Pragma directives will be defined in HTTP. |
| * |
| * <p> |
| * Note: because the meaning of "Pragma: no-cache as a response header field is not actually specified, it does not |
| * provide a reliable replacement for "Cache-Control: no-cache" in a response. |
| * |
| * <ul class='seealso'> |
| * <li class='extlink'>{@doc RFC2616} |
| * </ul> |
| */ |
| @Header("Pragma") |
| public final class Pragma extends HeaderString { |
| |
| /** |
| * Returns a parsed <c>Pragma</c> header. |
| * |
| * @param value The <c>Pragma</c> header string. |
| * @return The parsed <c>Pragma</c> header, or <jk>null</jk> if the string was null. |
| */ |
| public static Pragma forString(String value) { |
| if (value == null) |
| return null; |
| return new Pragma(value); |
| } |
| |
| private Pragma(String value) { |
| super(value); |
| } |
| } |