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>Referer</l> HTTP request header. 019 * 020 * <p> 021 * This is the address of the previous web page from which a link to the currently requested page was followed. 022 * (The word “referrer” has been misspelled in the RFC as well as in most implementations to the point that it has 023 * become standard usage and is considered correct terminology) 024 * 025 * <h5 class='figure'>Example</h5> 026 * <p class='bcode w800'> 027 * Referer: http://en.wikipedia.org/wiki/Main_Page 028 * </p> 029 * 030 * <h5 class='topic'>RFC2616 Specification</h5> 031 * 032 * The Referer[sic] request-header field allows the client to specify, for the server's benefit, the address (URI) of 033 * the resource from which the Request-URI was obtained (the "referrer", although the header field is misspelled.) 034 * The Referer request-header allows a server to generate lists of back-links to resources for interest, logging, 035 * optimized caching, etc. 036 * It also allows obsolete or mistyped links to be traced for maintenance. 037 * The Referer field MUST NOT be sent if the Request-URI was obtained from a source that does not have its own URI, 038 * such as input from the user keyboard. 039 * 040 * <p class='bcode w800'> 041 * Referer = "Referer" ":" ( absoluteURI | relativeURI ) 042 * </p> 043 * 044 * <p> 045 * Example: 046 * <p class='bcode w800'> 047 * Referer: http://www.w3.org/hypertext/DataSources/Overview.html 048 * </p> 049 * 050 * <p> 051 * If the field value is a relative URI, it SHOULD be interpreted relative to the Request-URI. 052 * The URI MUST NOT include a fragment. See section 15.1.3 for security considerations. 053 * 054 * <ul class='seealso'> 055 * <li class='extlink'>{@doc RFC2616} 056 * </ul> 057 */ 058@Header("Referer") 059public final class Referer extends HeaderUri { 060 061 /** 062 * Returns a parsed <c>Referer</c> header. 063 * 064 * @param value The <c>Referer</c> header string. 065 * @return The parsed <c>Referer</c> header, or <jk>null</jk> if the string was null. 066 */ 067 public static Referer forString(String value) { 068 if (value == null) 069 return null; 070 return new Referer(value); 071 } 072 073 private Referer(String value) { 074 super(value); 075 } 076}