Class MediaType

guava/src/com/google/common/net/MediaType.java:74–1265

Represents an <a href="http://en.wikipedia.org/wiki/Internet_media_type">Internet Media Type</a> (also known as a MIME Type or Content Type). This class also supports the concept of media ranges <a href="http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.1">defined by HTTP/1.1</a>. As such

 * @author Gregory Kick
 */
@GwtCompatible
@Immutable
public final class MediaType {
  private static final String CHARSET_ATTRIBUTE = "charset";
  private static final ImmutableListMultimap<String, String> UTF_8_CONSTANT_PARAMETERS =
      ImmutableListMultimap.of(CHARSET_ATTRIBUTE, Ascii.toLowerCase(UTF_8.name()));

  /** Matcher for type, subtype and attributes. */
  private static final CharMatcher TOKEN_MATCHER =
      ascii()
          .and(javaIsoControl().negate())
          .and(CharMatcher.isNot(' '))
          .and(CharMatcher.noneOf("()<>@,;:\\\"/[]?="));

  private static final CharMatcher QUOTED_TEXT_MATCHER = ascii().and(CharMatcher.noneOf("\"\\\r"));

  /*
   * This matches the same characters as linear-white-space from RFC 822, but we make no effort to
   * enforce any particular rules with regards to line folding as stated in the class docs.
   */
  private static final CharMatcher LINEAR_WHITE_SPACE = CharMatcher.anyOf(" \t\r\n");

  // TODO(gak): make these public?
  private static final String APPLICATION_TYPE = "application";
  private static final String AUDIO_TYPE = "audio";
  private static final String IMAGE_TYPE = "image";
  private static final String TEXT_TYPE = "text";
  private static final String VIDEO_TYPE = "video";
  private static final String FONT_TYPE = "font";

  private static final String WILDCARD = "*";

  private static final Map<MediaType, MediaType> knownTypes = new HashMap<>();

  private static MediaType createConstant(String type, String subtype) {
    MediaType mediaType =
        addKnownType(new MediaType(type, subtype, ImmutableListMultimap.<String, String>of()));
    mediaType.parsedCharset = Optional.absent();
    return mediaType;
  }

  private static MediaType createConstantUtf8(String type, String subtype) {
    MediaType mediaType = addKnownType(new MediaType(type, subtype, UTF_8_CONSTANT_PARAMETERS));
    mediaType.parsedCharset = Optional.of(UTF_8);
    return mediaType;
  }

  @CanIgnoreReturnValue
  private static MediaType addKnownType(MediaType mediaType) {
    knownTypes.put(mediaType, mediaType);
    return mediaType;
  }

  /*
   * The following constants are grouped by their type and ordered alphabetically by the constant
   * name within that type. The constant name should be a sensible identifier that is closest to the
   * "common name" of the media. This is often, but not necessarily the same as the subtype.
   *