001// ***************************************************************************************************************************
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006// *                                                                                                                         *
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012// ***************************************************************************************************************************
013package org.apache.juneau.http;
014
015/**
016 * Represents a parsed <l>Content-Length</l> HTTP request/response header.
017 * 
018 * <p>
019 * The length of the response body in octets (8-bit bytes).
020 * 
021 * <h5 class='figure'>Example</h5>
022 * <p class='bcode'>
023 *    Content-Length: 348
024 * </p>
025 * 
026 * <h5 class='topic'>RFC2616 Specification</h5>
027 * 
028 * The Content-Length entity-header field indicates the size of the entity-body, in decimal number of OCTETs, sent to
029 * the recipient or, in the case of the HEAD method, the size of the entity-body that would have been sent had the
030 * request been a GET.
031 * <p class='bcode'>
032 *    Content-Length    = "Content-Length" ":" 1*DIGIT
033 * </p>
034 * 
035 * <p>
036 * An example is...
037 * <p class='bcode'>
038 *    Content-Length: 3495
039 * </p>
040 * 
041 * <p>
042 * Applications SHOULD use this field to indicate the transfer-length of the message-body, unless this is prohibited by
043 * the rules in section 4.4.
044 * 
045 * <p>
046 * Any Content-Length greater than or equal to zero is a valid value.
047 * Section 4.4 describes how to determine the length of a message-body if a Content-Length is not given.
048 * 
049 * <p>
050 * Note that the meaning of this field is significantly different from the corresponding definition in MIME, where it is
051 * an optional field used within the "message/external-body" content-type.
052 * In HTTP, it SHOULD be sent whenever the message's length can be determined prior to being transferred, unless this is
053 * prohibited by the rules in section 4.4.
054 * 
055 * <h5 class='section'>See Also:</h5>
056 * <ul class='doctree'>
057 *    <li class='extlink'><a class='doclink' href='https://www.w3.org/Protocols/rfc2616/rfc2616.html'>Hypertext Transfer Protocol -- HTTP/1.1</a>
058 * </ul>
059 */
060public final class ContentLength extends HeaderInteger {
061
062   /**
063    * Returns a parsed <code>Content-Length</code> header.
064    * 
065    * @param value The <code>Content-Length</code> header string.
066    * @return The parsed <code>Content-Length</code> header, or <jk>null</jk> if the string was null.
067    */
068   public static ContentLength forString(String value) {
069      if (value == null)
070         return null;
071      return new ContentLength(value);
072   }
073
074   private ContentLength(String value) {
075      super(value);
076   }
077}