| // *************************************************************************************************************************** |
| // * 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 static org.apache.juneau.http.Constants.*; |
| import static org.apache.juneau.internal.CollectionUtils.*; |
| import static org.apache.juneau.internal.StringUtils.*; |
| |
| import java.util.*; |
| |
| import org.apache.juneau.http.annotation.*; |
| import org.apache.juneau.internal.*; |
| |
| /** |
| * Represents a parsed <l>Accept</l> HTTP request header. |
| * |
| * <p> |
| * Content-Types that are acceptable for the response. |
| * |
| * <h5 class='figure'>Example</h5> |
| * <p class='bcode w800'> |
| * Accept: text/plain |
| * </p> |
| * |
| * <h5 class='topic'>RFC2616 Specification</h5> |
| * |
| * The Accept request-header field can be used to specify certain media types which are acceptable for the response. |
| * Accept headers can be used to indicate that the request is specifically limited to a small set of desired types, as |
| * in the case of a request for an in-line image. |
| * |
| * <p class='bcode w800'> |
| * Accept = "Accept" ": |
| * #( media-range [ accept-params ] ) |
| * |
| * media-range = ( "* /*" |
| * | ( type "/" "*" ) |
| * | ( type "/" subtype ) |
| * ) *( ";" parameter ) |
| * accept-params = ";" "q" "=" qvalue *( accept-extension ) |
| * accept-extension = ";" token [ "=" ( token | quoted-string ) ] |
| * </p> |
| * |
| * <p> |
| * The asterisk "*" character is used to group media types into ranges, with "* /*" indicating all media types and |
| * "type/*" indicating all subtypes of that type. |
| * The media-range MAY include media type parameters that are applicable to that range. |
| * |
| * <p> |
| * Each media-range MAY be followed by one or more accept-params, beginning with the "q" parameter for indicating a |
| * relative quality factor. |
| * The first "q" parameter (if any) separates the media-range parameter(s) from the accept-params. |
| * Quality factors allow the user or user agent to indicate the relative degree of preference for that media-range, |
| * using the qvalue scale from 0 to 1 (section 3.9). |
| * The default value is q=1. |
| * |
| * <p> |
| * Note: Use of the "q" parameter name to separate media type parameters from Accept extension parameters is due to |
| * historical practice. |
| * Although this prevents any media type parameter named "q" from being used with a media range, such an event is |
| * believed to be unlikely given the lack of any "q" parameters in the IANA |
| * media type registry and the rare usage of any media type parameters in Accept. |
| * Future media types are discouraged from registering any parameter named "q". |
| * |
| * <p> |
| * The example |
| * <p class='bcode w800'> |
| * Accept: audio/*; q=0.2, audio/basic |
| * </p> |
| * <p> |
| * SHOULD be interpreted as "I prefer audio/basic, but send me any audio type if it is the best available after an 80% |
| * mark-down in quality." |
| * |
| * <p> |
| * If no Accept header field is present, then it is assumed that the client accepts all media types. |
| * |
| * <p> |
| * If an Accept header field is present, and if the server cannot send a response which is acceptable according to the |
| * combined Accept field value, then the server SHOULD send a 406 (not acceptable) response. |
| * |
| * <p> |
| * A more elaborate example is |
| * <p class='bcode w800'> |
| * Accept: text/plain; q=0.5, text/html, |
| * text/x-dvi; q=0.8, text/x-c |
| * </p> |
| * |
| * <p> |
| * Verbally, this would be interpreted as "text/html and text/x-c are the preferred media types, but if they do not |
| * exist, then send the |
| * text/x-dvi entity, and if that does not exist, send the text/plain entity." |
| * |
| * <p> |
| * Media ranges can be overridden by more specific media ranges or specific media types. |
| * If more than one media range applies to a given type, the most specific reference has precedence. |
| * For example, |
| * <p class='bcode w800'> |
| * Accept: text/ *, text/html, text/html;level=1, * /* |
| * </p> |
| * <p> |
| * have the following precedence: |
| * <ol> |
| * <li>text/html;level=1 |
| * <li>text/html |
| * <li>text/* |
| * <li>* /* |
| * </ol> |
| * |
| * <p> |
| * The media type quality factor associated with a given type is determined by finding the media range with the highest |
| * precedence which matches that type. |
| * For example, |
| * <p class='bcode w800'> |
| * Accept: text/*;q=0.3, text/html;q=0.7, text/html;level=1, |
| * text/html;level=2;q=0.4, * /*;q=0.5 |
| * </p> |
| * <p> |
| * would cause the following values to be associated: |
| * <p class='bcode w800'> |
| * text/html;level=1 = 1 |
| * text/html = 0.7 |
| * text/plain = 0.3 |
| * image/jpeg = 0.5 |
| * text/html;level=2 = 0.4 |
| * text/html;level=3 = 0.7 |
| * </p> |
| * |
| * <p> |
| * Note: A user agent might be provided with a default set of quality values for certain media ranges. |
| * However, unless the user agent is a closed system which cannot interact with other rendering agents, this default |
| * set ought to be configurable by the user. |
| * |
| * <ul class='seealso'> |
| * <li class='extlink'>{@doc RFC2616} |
| * </ul> |
| */ |
| @Header("Accept") |
| public final class Accept { |
| |
| private static final Cache<String,Accept> cache = new Cache<>(NOCACHE, CACHE_MAX_SIZE); |
| |
| /** |
| * Returns a parsed <c>Accept</c> header. |
| * |
| * @param value The <c>Accept</c> header string. |
| * @return The parsed <c>Accept</c> header, or <jk>null</jk> if the string was null. |
| */ |
| public static Accept forString(String value) { |
| if (value == null) |
| return null; |
| Accept a = cache.get(value); |
| if (a == null) |
| a = cache.put(value, new Accept(value)); |
| return a; |
| } |
| |
| |
| private final MediaTypeRange[] mediaRanges; |
| private final List<MediaTypeRange> mediaRangesList; |
| |
| private Accept(String value) { |
| this.mediaRanges = MediaTypeRange.parse(value); |
| this.mediaRangesList = immutableList(mediaRanges); |
| } |
| |
| /** |
| * Returns the list of the media ranges that make up this header. |
| * |
| * <p> |
| * The media ranges in the list are sorted by their q-value in descending order. |
| * |
| * @return An unmodifiable list of media ranges. |
| */ |
| public List<MediaTypeRange> asRanges() { |
| return mediaRangesList; |
| } |
| |
| /** |
| * Given a list of media types, returns the best match for this <c>Accept</c> header. |
| * |
| * <p> |
| * Note that fuzzy matching is allowed on the media types where the <c>Accept</c> header may |
| * contain additional subtype parts. |
| * <br>For example, given identical q-values and an <c>Accept</c> value of <js>"text/json+activity"</js>, |
| * the media type <js>"text/json"</js> will match if <js>"text/json+activity"</js> or <js>"text/activity+json"</js> |
| * isn't found. |
| * <br>The purpose for this is to allow serializers to match when artifacts such as <c>id</c> properties are |
| * present in the header. |
| * |
| * <p> |
| * See {@doc https://www.w3.org/TR/activitypub/#retrieving-objects ActivityPub / Retrieving Objects} |
| * |
| * @param mediaTypes The media types to match against. |
| * @return The index into the array of the best match, or <c>-1</c> if no suitable matches could be found. |
| */ |
| public int findMatch(MediaType[] mediaTypes) { |
| int matchQuant = 0, matchIndex = -1; |
| float q = 0f; |
| |
| // Media ranges are ordered by 'q'. |
| // So we only need to search until we've found a match. |
| for (MediaTypeRange mr : mediaRanges) { |
| float q2 = mr.getQValue(); |
| |
| if (q2 < q || q2 == 0) |
| break; |
| |
| for (int i = 0; i < mediaTypes.length; i++) { |
| MediaType mt = mediaTypes[i]; |
| int matchQuant2 = mr.getMediaType().match(mt, false); |
| |
| if (matchQuant2 > matchQuant) { |
| matchIndex = i; |
| matchQuant = matchQuant2; |
| q = q2; |
| } |
| } |
| } |
| |
| return matchIndex; |
| } |
| |
| /** |
| * Same as {@link #findMatch(MediaType[])} but matching against media type ranges. |
| * |
| * <p> |
| * Note that the q-types on both the <c>mediaTypeRanges</c> parameter and this header |
| * are taken into account when trying to find the best match. |
| * <br>When both this header and the matching range have q-values, the q-value for the match is the result of multiplying them. |
| * <br>(e.g. Accept=<js>"text/html;q=0.9"</js> and mediaTypeRange=<js>"text/html;q=0.9"</js> ==>, q-value=<c>0.81</c>). |
| * |
| * @param mediaTypeRanges The media type ranges to match against. |
| * @return The index into the array of the best match, or <c>-1</c> if no suitable matches could be found. |
| */ |
| public int findMatch(MediaTypeRange[] mediaTypeRanges) { |
| float matchQuant = 0; |
| int matchIndex = -1; |
| float q = 0f; |
| |
| // Media ranges are ordered by 'q'. |
| // So we only need to search until we've found a match. |
| for (MediaTypeRange mr : mediaRanges) { |
| float q2 = mr.getQValue(); |
| |
| if (q2 < q || q2 == 0) |
| break; |
| |
| for (int i = 0; i < mediaTypeRanges.length; i++) { |
| MediaTypeRange mt = mediaTypeRanges[i]; |
| float matchQuant2 = mr.getMediaType().match(mt.getMediaType(), false) * mt.getQValue(); |
| |
| if (matchQuant2 > matchQuant) { |
| matchIndex = i; |
| matchQuant = matchQuant2; |
| q = q2; |
| } |
| } |
| } |
| |
| return matchIndex; |
| } |
| |
| |
| /** |
| * Convenience method for searching through all of the subtypes of all the media ranges in this header for the |
| * presence of a subtype fragment. |
| * |
| * <p> |
| * For example, given the header <js>"text/json+activity"</js>, calling |
| * <code>hasSubtypePart(<js>"activity"</js>)</code> returns <jk>true</jk>. |
| * |
| * @param part The media type subtype fragment. |
| * @return <jk>true</jk> if subtype fragment exists. |
| */ |
| public boolean hasSubtypePart(String part) { |
| |
| for (MediaTypeRange mr : this.mediaRanges) |
| if (mr.getQValue() > 0 && mr.getMediaType().getSubTypes().indexOf(part) >= 0) |
| return true; |
| |
| return false; |
| } |
| |
| @Override /* Object */ |
| public String toString() { |
| return join(mediaRanges, ','); |
| } |
| } |