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 static org.apache.juneau.internal.StringUtils.*; 016 017import org.apache.juneau.http.annotation.*; 018import org.apache.juneau.internal.*; 019 020/** 021 * Represents a parsed <l>If-Range</l> HTTP request header. 022 * 023 * <p> 024 * If the entity is unchanged, send me the part(s) that I am missing; otherwise, send me the entire new entity. 025 * 026 * <h5 class='figure'>Example</h5> 027 * <p class='bcode w800'> 028 * If-Range: "737060cd8c284d8af7ad3082f209582d" 029 * </p> 030 * 031 * <h5 class='topic'>RFC2616 Specification</h5> 032 * 033 * If a client has a partial copy of an entity in its cache, and wishes to have an up-to-date copy of the entire entity 034 * in its cache, it could use the Range request-header with a conditional GET (using either or both of 035 * If-Unmodified-Since and If-Match.) 036 * However, if the condition fails because the entity has been modified, the client would then have to make a second 037 * request to obtain the entire current entity-body. 038 * 039 * <p> 040 * The If-Range header allows a client to "short-circuit" the second request. 041 * Informally, its meaning is `if the entity is unchanged, send me the part(s) that I am missing; otherwise, send me 042 * the entire new entity'. 043 * <p class='bcode w800'> 044 * If-Range = "If-Range" ":" ( entity-tag | HTTP-date ) 045 * </p> 046 * 047 * <p> 048 * If the client has no entity tag for an entity, but does have a Last- Modified date, it MAY use that date in an 049 * If-Range header. 050 * (The server can distinguish between a valid HTTP-date and any form of entity-tag by examining no more than two 051 * characters.) 052 * The If-Range header SHOULD only be used together with a Range header, and MUST be ignored if the request does not 053 * include a Range header, or if the server does not support the sub-range operation. 054 * 055 * <p> 056 * If the entity tag given in the If-Range header matches the current entity tag for the entity, then the server SHOULD 057 * provide the specified sub-range of the entity using a 206 (Partial content) response. 058 * If the entity tag does not match, then the server SHOULD return the entire entity using a 200 (OK) response. 059 * 060 * <h5 class='section'>See Also:</h5> 061 * <ul class='doctree'> 062 * <li class='extlink'>{@doc RFC2616} 063 * </ul> 064 */ 065@Header("If-Range") 066public final class IfRange extends HeaderString { 067 068 /** 069 * Returns a parsed <code>If-Range</code> header. 070 * 071 * @param value The <code>If-Range</code> header string. 072 * @return The parsed <code>If-Range</code> header, or <jk>null</jk> if the string was null. 073 */ 074 public static IfRange forString(String value) { 075 if (value == null) 076 return null; 077 return new IfRange(value); 078 } 079 080 private IfRange(String value) { 081 super(value); 082 } 083 084 /** 085 * Returns this header value as a {@link java.util.Date} object. 086 * 087 * @return This header value as a {@link java.util.Date} object, or <jk>null</jk> if the value is not a date. 088 */ 089 public java.util.Date asDate() { 090 char c0 = charAt(value, 0), c1 = charAt(value, 1); 091 if (c0 == '*' || c0 == '"' || (c0 == 'W' && c1 == '/')) 092 return null; 093 return DateUtils.parseDate(toString()); 094 } 095 096 /** 097 * Returns this header value as an {@link EntityValidator} object. 098 * 099 * @return 100 * This header value as a {@link EntityValidator} object, or <jk>null</jk> if the value is not an entity 101 * validator. 102 */ 103 public EntityValidator asValidator() { 104 char c0 = charAt(value, 0), c1 = charAt(value, 1); 105 if (c0 == '*' || c0 == '"' || (c0 == 'W' && c1 == '/')) 106 return new EntityValidator(value); 107 return null; 108 } 109}