Source code

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;
014
015import static org.apache.juneau.common.internal.StringUtils.*;
016import static org.apache.juneau.internal.CollectionUtils.*;
017
018import java.util.*;
019import java.util.function.*;
020
021import org.apache.http.*;
022import org.apache.http.message.*;
023import org.apache.juneau.annotation.*;
024import org.apache.juneau.common.internal.*;
025import org.apache.juneau.internal.*;
026
027/**
028 * A parsed <c>Accept</c> or similar header value.
029 *
030 * <p>
031 * The returned media ranges are sorted such that the most acceptable media is available at ordinal position
032 * <js>'0'</js>, and the least acceptable at position n-1.
033 *
034 * <p>
035 * The syntax expected to be found in the referenced <c>value</c> complies with the syntax described in
036 * RFC2616, Section 14.1, as described below:
037 * <p class='bcode'>
038 *    Accept         = "Accept" ":"
039 *                      #( media-range [ accept-params ] )
040 *
041 *    media-range    = ( "*\/*"
042 *                      | ( type "/" "*" )
043 *                      | ( type "/" subtype )
044 *                      ) *( ";" parameter )
045 *    accept-params  = ";" "q" "=" qvalue *( accept-extension )
046 *    accept-extension = ";" token [ "=" ( token | quoted-string ) ]
047 * </p>
048 *
049 * <h5 class='section'>See Also:</h5><ul>
050 *    <li class='link'><a class="doclink" href="../../../index.html#juneau-rest-common">juneau-rest-common</a>
051 *    <li class='extlink'><a class="doclink" href="https://www.w3.org/Protocols/rfc2616/rfc2616.html">Hypertext Transfer Protocol -- HTTP/1.1</a>
052 * </ul>
053 */
054@BeanIgnore
055public class MediaRanges {
056
057   //-----------------------------------------------------------------------------------------------------------------
058   // Static
059   //-----------------------------------------------------------------------------------------------------------------
060
061   /** Represents an empty media ranges object. */
062   public static final MediaRanges EMPTY = new MediaRanges("");
063
064   private static final Cache<String,MediaRanges> CACHE = Cache.of(String.class, MediaRanges.class).build();
065
066   private final MediaRange[] ranges;
067   private final String string;
068
069   /**
070    * Returns a parsed <c>Accept</c> header value.
071    *
072    * @param value The raw <c>Accept</c> header value.
073    * @return A parsed <c>Accept</c> header value.
074    */
075   public static MediaRanges of(String value) {
076      return isEmpty(value) ? EMPTY : CACHE.get(value, ()->new MediaRanges(value));
077   }
078
079   //-----------------------------------------------------------------------------------------------------------------
080   // Instance
081   //-----------------------------------------------------------------------------------------------------------------
082
083   /**
084    * Constructor.
085    *
086    * @param value The <c>Accept</c> header value.
087    */
088   public MediaRanges(String value) {
089      this(parse(value));
090   }
091
092   /**
093    * Constructor.
094    *
095    * @param e The parsed header value.
096    */
097   public MediaRanges(HeaderElement[] e) {
098
099      ranges = new MediaRange[e.length];
100      for (int i = 0; i < e.length; i++)
101         ranges[i] = new MediaRange(e[i]);
102      Arrays.sort(ranges, RANGE_COMPARATOR);
103
104      this.string = ranges.length == 1 ? ranges[0].toString() : StringUtils.join(ranges, ',');
105   }
106
107   /**
108    * Compares two MediaRanges for equality.
109    *
110    * <p>
111    * The values are first compared according to <c>qValue</c> values.
112    * Should those values be equal, the <c>type</c> is then lexicographically compared (case-insensitive) in
113    * ascending order, with the <js>"*"</js> type demoted last in that order.
114    * <c>MediaRanges</c> with the same type but different sub-types are compared - a more specific subtype is
115    * promoted over the 'wildcard' subtype.
116    * <c>MediaRanges</c> with the same types but with extensions are promoted over those same types with no
117    * extensions.
118    */
119   private static final Comparator<MediaRange> RANGE_COMPARATOR = new Comparator<>() {
120      @Override
121      public int compare(MediaRange o1, MediaRange o2) {
122         // Compare q-values.
123         int qCompare = Float.compare(o2.getQValue(), o1.getQValue());
124         if (qCompare != 0)
125            return qCompare;
126
127         // Compare media-types.
128         // Note that '*' comes alphabetically before letters, so just do a reverse-alphabetical comparison.
129         int i = o2.toString().compareTo(o1.toString());
130         return i;
131      }
132   };
133
134   /**
135    * Given a list of media types, returns the best match for this <c>Accept</c> header.
136    *
137    * <p>
138    * Note that fuzzy matching is allowed on the media types where the <c>Accept</c> header may
139    * contain additional subtype parts.
140    * <br>For example, given identical q-values and an <c>Accept</c> value of <js>"text/json+activity"</js>,
141    * the media type <js>"text/json"</js> will match if <js>"text/json+activity"</js> or <js>"text/activity+json"</js>
142    * isn't found.
143    * <br>The purpose for this is to allow serializers to match when artifacts such as <c>id</c> properties are
144    * present in the header.
145    *
146    * <p>
147    * See <a class="doclink" href="https://www.w3.org/TR/activitypub/#retrieving-objects">ActivityPub / Retrieving Objects</a>
148    *
149    * @param mediaTypes The media types to match against.
150    * @return The index into the array of the best match, or <c>-1</c> if no suitable matches could be found.
151    */
152   public int match(List<? extends MediaType> mediaTypes) {
153      if (string.isEmpty() || mediaTypes == null)
154         return -1;
155
156      int matchQuant = 0, matchIndex = -1;
157      float q = 0f;
158
159      // Media ranges are ordered by 'q'.
160      // So we only need to search until we've found a match.
161      for (MediaRange mr : ranges) {
162         float q2 = mr.getQValue();
163
164         if (q2 < q || q2 == 0)
165            break;
166
167         for (int i = 0; i < mediaTypes.size(); i++) {
168            MediaType mt = mediaTypes.get(i);
169            int matchQuant2 = mr.match(mt, false);
170
171            if (matchQuant2 > matchQuant) {
172               matchIndex = i;
173               matchQuant = matchQuant2;
174               q = q2;
175            }
176         }
177      }
178
179      return matchIndex;
180   }
181
182   /**
183    * Returns the {@link MediaRange} at the specified index.
184    *
185    * @param index The index position of the media range.
186    * @return The {@link MediaRange} at the specified index or <jk>null</jk> if the index is out of range.
187    */
188   public MediaRange getRange(int index) {
189      if (index < 0 || index >= ranges.length)
190         return null;
191      return ranges[index];
192   }
193
194   /**
195    * Convenience method for searching through all of the subtypes of all the media ranges in this header for the
196    * presence of a subtype fragment.
197    *
198    * <p>
199    * For example, given the header <js>"text/json+activity"</js>, calling
200    * <code>hasSubtypePart(<js>"activity"</js>)</code> returns <jk>true</jk>.
201    *
202    * @param part The media type subtype fragment.
203    * @return <jk>true</jk> if subtype fragment exists.
204    */
205   public boolean hasSubtypePart(String part) {
206
207      for (MediaRange mr : ranges)
208         if (mr.getQValue() > 0 && mr.getSubTypes().indexOf(part) >= 0)
209            return true;
210
211      return false;
212   }
213
214   /**
215    * Returns the media ranges that make up this object.
216    *
217    * @return The media ranges that make up this object.
218    */
219   public List<MediaRange> toList() {
220      return ulist(ranges);
221   }
222
223   /**
224    * Performs an action on the media ranges that make up this object.
225    *
226    * @param action The action to perform.
227    * @return This object.
228    */
229   public MediaRanges forEachRange(Consumer<MediaRange> action) {
230      for (MediaRange r : ranges)
231         action.accept(r);
232      return this;
233   }
234
235   private static HeaderElement[] parse(String value) {
236      return BasicHeaderValueParser.parseElements(emptyIfNull(trim(value)), null);
237   }
238
239   @Override /* Object */
240   public String toString() {
241      return string;
242   }
243}