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.http; 014 015import org.apache.juneau.http.annotation.*; 016 017/** 018 * Represents a parsed <l>Trailer</l> HTTP response header. 019 * 020 * <p> 021 * The Trailer general field value indicates that the given set of header fields is present in the trailer of a message 022 * encoded with chunked transfer coding. 023 * 024 * <h5 class='figure'>Example</h5> 025 * <p class='bcode w800'> 026 * Trailer: Max-Forwards 027 * </p> 028 * 029 * <h5 class='topic'>RFC2616 Specification</h5> 030 * 031 * The Trailer general field value indicates that the given set of header fields is present in the trailer of a message 032 * encoded with chunked transfer-coding. 033 * 034 * <p class='bcode w800'> 035 * Trailer = "Trailer" ":" 1#field-name 036 * </p> 037 * 038 * <p> 039 * An HTTP/1.1 message SHOULD include a Trailer header field in a message using chunked transfer-coding with a non-empty 040 * trailer. 041 * Doing so allows the recipient to know which header fields to expect in the trailer. 042 * 043 * <p> 044 * If no Trailer header field is present, the trailer SHOULD NOT include any header fields. 045 * See section 3.6.1 for restrictions on the use of trailer fields in a "chunked" transfer-coding. 046 * 047 * <p> 048 * Message header fields listed in the Trailer header field MUST NOT include the following header fields: 049 * <ul> 050 * <li>Transfer-Encoding 051 * <li>Content-Length 052 * <li>Trailer 053 * </ul> 054 * 055 * <ul class='seealso'> 056 * <li class='extlink'>{@doc RFC2616} 057 * </ul> 058 */ 059@Header("Trailer") 060public final class Trailer extends HeaderString { 061 062 /** 063 * Returns a parsed <c>Trailer</c> header. 064 * 065 * @param value The <c>Trailer</c> header string. 066 * @return The parsed <c>Trailer</c> header, or <jk>null</jk> if the string was null. 067 */ 068 public static Trailer forString(String value) { 069 if (value == null) 070 return null; 071 return new Trailer(value); 072 } 073 074 private Trailer(String value) { 075 super(value); 076 } 077}