001/* 002 * Licensed to the Apache Software Foundation (ASF) under one or more 003 * contributor license agreements. See the NOTICE file distributed with 004 * this work for additional information regarding copyright ownership. 005 * The ASF licenses this file to You under the Apache License, Version 2.0 006 * (the "License"); you may not use this file except in compliance with 007 * the License. You may obtain a copy of the License at 008 * 009 * http://www.apache.org/licenses/LICENSE-2.0 010 * 011 * Unless required by applicable law or agreed to in writing, software 012 * distributed under the License is distributed on an "AS IS" BASIS, 013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 014 * See the License for the specific language governing permissions and 015 * limitations under the License. 016 */ 017package org.apache.juneau.http.header; 018 019import java.util.function.*; 020 021import org.apache.juneau.*; 022import org.apache.juneau.http.annotation.*; 023import org.apache.juneau.internal.*; 024 025/** 026 * Represents a parsed <l>Accept</l> HTTP request header. 027 * 028 * <p> 029 * Content-Types that are acceptable for the response. 030 * 031 * <h5 class='figure'>Example</h5> 032 * <p class='bcode'> 033 * Accept: text/plain 034 * </p> 035 * 036 * <h5 class='topic'>RFC2616 Specification</h5> 037 * 038 * The Accept request-header field can be used to specify certain media types which are acceptable for the response. 039 * Accept headers can be used to indicate that the request is specifically limited to a small set of desired types, as 040 * in the case of a request for an in-line image. 041 * 042 * <p class='bcode'> 043 * Accept = "Accept" ": 044 * #( media-range [ accept-params ] ) 045 * 046 * media-range = ( "* /*" 047 * | ( type "/" "*" ) 048 * | ( type "/" subtype ) 049 * ) *( ";" parameter ) 050 * accept-params = ";" "q" "=" qvalue *( accept-extension ) 051 * accept-extension = ";" token [ "=" ( token | quoted-string ) ] 052 * </p> 053 * 054 * <p> 055 * The asterisk "*" character is used to group media types into ranges, with "* /*" indicating all media types and 056 * "type/*" indicating all subtypes of that type. 057 * The media-range MAY include media type parameters that are applicable to that range. 058 * 059 * <p> 060 * Each media-range MAY be followed by one or more accept-params, beginning with the "q" parameter for indicating a 061 * relative quality factor. 062 * The first "q" parameter (if any) separates the media-range parameter(s) from the accept-params. 063 * Quality factors allow the user or user agent to indicate the relative degree of preference for that media-range, 064 * using the qvalue scale from 0 to 1 (section 3.9). 065 * The default value is q=1. 066 * 067 * <p> 068 * Note: Use of the "q" parameter name to separate media type parameters from Accept extension parameters is due to 069 * historical practice. 070 * Although this prevents any media type parameter named "q" from being used with a media range, such an event is 071 * believed to be unlikely given the lack of any "q" parameters in the IANA 072 * media type registry and the rare usage of any media type parameters in Accept. 073 * Future media types are discouraged from registering any parameter named "q". 074 * 075 * <p> 076 * The example 077 * <p class='bcode'> 078 * Accept: audio/*; q=0.2, audio/basic 079 * </p> 080 * <p> 081 * SHOULD be interpreted as "I prefer audio/basic, but send me any audio type if it is the best available after an 80% 082 * mark-down in quality." 083 * 084 * <p> 085 * If no Accept header field is present, then it is assumed that the client accepts all media types. 086 * 087 * <p> 088 * If an Accept header field is present, and if the server cannot send a response which is acceptable according to the 089 * combined Accept field value, then the server SHOULD send a 406 (not acceptable) response. 090 * 091 * <p> 092 * A more elaborate example is 093 * <p class='bcode'> 094 * Accept: text/plain; q=0.5, text/html, 095 * text/x-dvi; q=0.8, text/x-c 096 * </p> 097 * 098 * <p> 099 * Verbally, this would be interpreted as "text/html and text/x-c are the preferred media types, but if they do not 100 * exist, then send the 101 * text/x-dvi entity, and if that does not exist, send the text/plain entity." 102 * 103 * <p> 104 * Media ranges can be overridden by more specific media ranges or specific media types. 105 * If more than one media range applies to a given type, the most specific reference has precedence. 106 * For example, 107 * <p class='bcode'> 108 * Accept: text/ *, text/html, text/html;level=1, * /* 109 * </p> 110 * <p> 111 * have the following precedence: 112 * <ol> 113 * <li>text/html;level=1 114 * <li>text/html 115 * <li>text/* 116 * <li>* /* 117 * </ol> 118 * 119 * <p> 120 * The media type quality factor associated with a given type is determined by finding the media range with the highest 121 * precedence which matches that type. 122 * For example, 123 * <p class='bcode'> 124 * Accept: text/*;q=0.3, text/html;q=0.7, text/html;level=1, 125 * text/html;level=2;q=0.4, * /*;q=0.5 126 * </p> 127 * <p> 128 * would cause the following values to be associated: 129 * <p class='bcode'> 130 * text/html;level=1 = 1 131 * text/html = 0.7 132 * text/plain = 0.3 133 * image/jpeg = 0.5 134 * text/html;level=2 = 0.4 135 * text/html;level=3 = 0.7 136 * </p> 137 * 138 * <p> 139 * Note: A user agent might be provided with a default set of quality values for certain media ranges. 140 * However, unless the user agent is a closed system which cannot interact with other rendering agents, this default 141 * set ought to be configurable by the user. 142 * 143 * <h5 class='section'>See Also:</h5><ul> 144 * <li class='link'><a class="doclink" href="https://juneau.apache.org/docs/topics/JuneauRestCommonBasics">juneau-rest-common Basics</a> 145 * <li class='extlink'><a class="doclink" href="https://www.w3.org/Protocols/rfc2616/rfc2616.html">Hypertext Transfer Protocol -- HTTP/1.1</a> 146 * </ul> 147 * 148 * @serial exclude 149 */ 150@Header("Accept") 151public class Accept extends BasicMediaRangesHeader { 152 153 //----------------------------------------------------------------------------------------------------------------- 154 // Static 155 //----------------------------------------------------------------------------------------------------------------- 156 157 private static final long serialVersionUID = 1L; 158 private static final String NAME = "Accept"; 159 160 private static final Cache<String,Accept> CACHE = Cache.of(String.class, Accept.class).build(); 161 162 // Constants 163 @SuppressWarnings("javadoc") 164 public static final Accept 165 APPLICATION_ATOM_XML = of("application/atom+xml"), 166 APPLICATION_FORM_URLENCODED = of("application/x-www-form-urlencoded"), 167 APPLICATION_JSON = of("application/json"), 168 APPLICATION_OCTET_STREAM = of("application/octet-stream"), 169 APPLICATION_SOAP_XML = of("application/soap+xml"), 170 APPLICATION_SVG_XML = of("application/svg+xml"), 171 APPLICATION_XHTML_XML = of("application/xhtml+xml"), 172 APPLICATION_XML = of("application/xml"), 173 IMAGE_BMP = of("image/bmp"), 174 IMAGE_GIF = of("image/gif"), 175 IMAGE_JPEG = of("image/jpeg"), 176 IMAGE_PNG = of("image/png"), 177 IMAGE_SVG = of("image/svg+xml"), 178 IMAGE_TIFF = of("image/tiff"), 179 IMAGE_WEBP = of("image/webp"), 180 MULTIPART_FORM_DATA = of("multipart/form-data"), 181 TEXT_HTML = of("text/html"), 182 TEXT_PLAIN = of("text/plain"), 183 TEXT_XML = of("text/xml"), 184 WILDCARD = of("*/*"), 185 NULL = new Accept((String)null); 186 187 /** 188 * Static creator. 189 * 190 * @param value 191 * The header value. 192 * <br>Must be parsable by {@link MediaRanges#of(String)}. 193 * <br>Can be <jk>null</jk>. 194 * @return A new header bean, or <jk>null</jk> if the value is <jk>null</jk>. 195 */ 196 public static Accept of(String value) { 197 return value == null ? null : CACHE.get(value, ()->new Accept(value)); 198 } 199 200 /** 201 * Static creator. 202 * 203 * @param value 204 * The header value. 205 * <br>Can be <jk>null</jk>. 206 * @return A new header bean, or <jk>null</jk> if the value is <jk>null</jk>. 207 */ 208 public static Accept of(MediaRanges value) { 209 return value == null ? null : new Accept(value); 210 } 211 212 /** 213 * Static creator. 214 * 215 * @param value 216 * The header value. 217 * <br>Can be <jk>null</jk>. 218 * @return A new header bean, or <jk>null</jk> if the value is <jk>null</jk>. 219 */ 220 public static Accept of(MediaType value) { 221 return value == null ? null : new Accept(value.toString()); 222 } 223 224 /** 225 * Static creator with delayed value. 226 * 227 * <p> 228 * Header value is re-evaluated on each call to {@link #getValue()}. 229 * 230 * @param value 231 * The header value. 232 * <br>Can be <jk>null</jk>. 233 * @return A new header bean, or <jk>null</jk> if the value is <jk>null</jk>. 234 */ 235 public static Accept of(Supplier<MediaRanges> value) { 236 return value == null ? null : new Accept(value); 237 } 238 239 //----------------------------------------------------------------------------------------------------------------- 240 // Instance 241 //----------------------------------------------------------------------------------------------------------------- 242 243 /** 244 * Constructor. 245 * 246 * @param value 247 * The header value. 248 * <br>Must be parsable by {@link MediaRanges#of(String)}. 249 * <br>Can be <jk>null</jk>. 250 */ 251 public Accept(String value) { 252 super(NAME, value); 253 } 254 255 /** 256 * Constructor. 257 * 258 * @param value 259 * The header value. 260 * <br>Can be <jk>null</jk>. 261 */ 262 public Accept(MediaRanges value) { 263 super(NAME, value); 264 } 265 266 /** 267 * Constructor with delayed value. 268 * 269 * <p> 270 * Header value is re-evaluated on each call to {@link #getValue()}. 271 * 272 * @param value 273 * The supplier of the header value. 274 * <br>Can be <jk>null</jk>. 275 */ 276 public Accept(Supplier<MediaRanges> value) { 277 super(NAME, value); 278 } 279}