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006// *                                                                                                                         *
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012// ***************************************************************************************************************************
013package org.apache.juneau.http;
014
015/**
016 * Represents a parsed <l>Content-Encoding</l> HTTP response header.
017 * 
018 * <p>
019 * The type of encoding used on the data.
020 * 
021 * <h5 class='figure'>Example</h5>
022 * <p class='bcode'>
023 *    Content-Encoding: gzip
024 * </p>
025 * 
026 * <h5 class='topic'>RFC2616 Specification</h5>
027 * 
028 * The Content-Encoding entity-header field is used as a modifier to the media-type.
029 * When present, its value indicates what additional content codings have been applied to the entity-body, and thus
030 * what decoding mechanisms must be applied in order to obtain the media-type referenced by the Content-Type header
031 * field.
032 * Content-Encoding is primarily used to allow a document to be compressed without losing the identity of its
033 * underlying media type.
034 * <p class='bcode'>
035 *    Content-Encoding  = "Content-Encoding" ":" 1#content-coding
036 * </p>
037 * 
038 * <p>
039 * Content codings are defined in section 3.5. An example of its use is...
040 * <p class='bcode'>
041 *    Content-Encoding: gzip
042 * </p>
043 * 
044 * <p>
045 * The content-coding is a characteristic of the entity identified by the Request-URI.
046 * Typically, the entity-body is stored with this encoding and is only decoded before rendering or analogous usage.
047 * However, a non-transparent proxy MAY modify the content-coding if the new coding is known to be acceptable to the
048 * recipient, unless the "no-transform" cache-control directive is present in the message.
049 * 
050 * <p>
051 * If the content-coding of an entity is not "identity", then the response MUST include a Content-Encoding
052 * entity-header (section 14.11) that lists the non-identity content-coding(s) used.
053 * 
054 * <p>
055 * If the content-coding of an entity in a request message is not acceptable to the origin server, the server SHOULD
056 * respond with a status code of 415 (Unsupported Media Type).
057 * 
058 * <p>
059 * If multiple encodings have been applied to an entity, the content codings MUST be listed in the order in which they
060 * were applied.
061 * Additional information about the encoding parameters MAY be provided.
062 * 
063 * <h5 class='section'>See Also:</h5>
064 * <ul class='doctree'>
065 *    <li class='extlink'><a class='doclink' href='https://www.w3.org/Protocols/rfc2616/rfc2616.html'>Hypertext Transfer Protocol -- HTTP/1.1</a>
066 * </ul>
067 */
068public final class ContentEncoding extends HeaderEnum<ContentEncodingEnum> {
069
070   /**
071    * Returns a parsed <code>Content-Encoding</code> header.
072    * 
073    * @param value The <code>Content-Encoding</code> header string.
074    * @return The parsed <code>Content-Encoding</code> header, or <jk>null</jk> if the string was null.
075    */
076   public static ContentEncoding forString(String value) {
077      if (value == null)
078         return null;
079      return new ContentEncoding(value);
080   }
081
082   private ContentEncoding(String value) {
083      super(value, ContentEncodingEnum.class, ContentEncodingEnum.OTHER);
084   }
085}