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012// ***************************************************************************************************************************
013package org.apache.juneau.http;
014
015/**
016 * Represents a parsed <l>Content-Language</l> HTTP response header.
017 * 
018 * <p>
019 * The natural language or languages of the intended audience for the enclosed content.
020 * 
021 * <h5 class='figure'>Example</h5>
022 * <p class='bcode'>
023 *    Content-Language: da
024 * </p>
025 * 
026 * <h5 class='topic'>RFC2616 Specification</h5>
027 * 
028 * The Content-Language entity-header field describes the natural language(s) of the intended audience for the
029 * enclosed entity.
030 * Note that this might not be equivalent to all the languages used within the entity-body.
031 * <p class='bcode'>
032 *    Content-Language  = "Content-Language" ":" 1#language-tag
033 * </p>
034 * 
035 * <p>
036 * Language tags are defined in section 3.10.
037 * The primary purpose of Content-Language is to allow a user to identify and differentiate entities according to the
038 * user's own preferred language.
039 * Thus, if the body content is intended only for a Danish-literate audience, the appropriate field is...
040 * <p class='bcode'>
041 *    Content-Language: da
042 * </p>
043 * 
044 * <p>
045 * If no Content-Language is specified, the default is that the content is intended for all language audiences.
046 * This might mean that the sender does not consider it to be specific to any natural language, or that the sender
047 * does not know for which language it is intended.
048 * 
049 * <p>
050 * Multiple languages MAY be listed for content that is intended for multiple audiences.
051 * For example, a rendition of the "Treaty of Waitangi," presented simultaneously in the original Maori and English
052 * versions, would call for...
053 * <p class='bcode'>
054 *    Content-Language: mi, en
055 * </p>
056 * 
057 * <p>
058 * However, just because multiple languages are present within an entity does not mean that it is intended for
059 * multiple linguistic audiences.
060 * An example would be a beginner's language primer, such as "A First Lesson in Latin," which is clearly intended to
061 * be used by an English-literate audience.
062 * In this case, the Content-Language would properly only include "en".
063 * 
064 * <p>
065 * Content-Language MAY be applied to any media type -- it is not limited to textual documents.
066 * 
067 * <h5 class='section'>See Also:</h5>
068 * <ul class='doctree'>
069 *    <li class='extlink'><a class='doclink' href='https://www.w3.org/Protocols/rfc2616/rfc2616.html'>Hypertext Transfer Protocol -- HTTP/1.1</a>
070 * </ul>
071 */
072public final class ContentLanguage extends HeaderStringArray {
073
074   /**
075    * Returns a parsed <code>Content-Language</code> header.
076    * 
077    * @param value The <code>Content-Language</code> header string.
078    * @return The parsed <code>Content-Language</code> header, or <jk>null</jk> if the string was null.
079    */
080   public static ContentLanguage forString(String value) {
081      if (value == null)
082         return null;
083      return new ContentLanguage(value);
084   }
085
086   private ContentLanguage(String value) {
087      super(value);
088   }
089}