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See the License for the * 011// * specific language governing permissions and limitations under the License. * 012// *************************************************************************************************************************** 013package org.apache.juneau.http.header; 014 015import static org.apache.juneau.http.Constants.*; 016 017import java.util.function.*; 018 019import org.apache.juneau.http.*; 020import org.apache.juneau.http.annotation.*; 021import org.apache.juneau.internal.*; 022 023/** 024 * Represents a parsed <l>Accept-Encoding</l> HTTP request header. 025 * 026 * <p> 027 * List of acceptable encodings. 028 * 029 * <h5 class='figure'>Example</h5> 030 * <p class='bcode w800'> 031 * Accept-Encoding: gzip, deflate 032 * </p> 033 * 034 * <h5 class='topic'>RFC2616 Specification</h5> 035 * 036 * The Accept-Encoding request-header field is similar to Accept, but restricts the content-codings (section 3.5) that 037 * are acceptable in the response. 038 * 039 * <p class='bcode w800'> 040 * Accept-Encoding = "Accept-Encoding" ":" 041 * 1#( codings [ ";" "q" "=" qvalue ] ) 042 * codings = ( content-coding | "*" ) 043 * </p> 044 * 045 * <p> 046 * Examples of its use are: 047 * <p class='bcode w800'> 048 * Accept-Encoding: compress, gzip 049 * Accept-Encoding: 050 * Accept-Encoding: * 051 * Accept-Encoding: compress;q=0.5, gzip;q=1.0 052 * Accept-Encoding: gzip;q=1.0, identity; q=0.5, *;q=0 053 * </p> 054 * 055 * <p> 056 * A server tests whether a content-coding is acceptable, according to an Accept-Encoding field, using these rules: 057 * <ol> 058 * <li>If the content-coding is one of the content-codings listed in the Accept-Encoding field, then it is 059 * acceptable, unless it is accompanied by a qvalue of 0. 060 * (As defined in section 3.9, a qvalue of 0 means "not acceptable.") 061 * <li>The special "*" symbol in an Accept-Encoding field matches any available content-coding not explicitly listed 062 * in the header field. 063 * <li>If multiple content-codings are acceptable, then the acceptable content-coding with the highest non-zero 064 * qvalue is preferred. 065 * <li>The "identity" content-coding is always acceptable, unless specifically refused because the Accept-Encoding 066 * field includes "identity;q=0", or because the field includes "*;q=0" and does not explicitly include the 067 * "identity" content-coding. 068 * If the Accept-Encoding field-value is empty, then only the "identity" encoding is acceptable. 069 * </ol> 070 * 071 * <p> 072 * If an Accept-Encoding field is present in a request, and if the server cannot send a response which is acceptable 073 * according to the Accept-Encoding header, then the server SHOULD send an error response with the 406 (Not Acceptable) 074 * status code. 075 * 076 * <p> 077 * If no Accept-Encoding field is present in a request, the server MAY assume that the client will accept any content 078 * coding. 079 * In this case, if "identity" is one of the available content-codings, then the server SHOULD use the "identity" 080 * content-coding, unless it has additional information that a different content-coding is meaningful to the client. 081 * 082 * <p> 083 * Note: If the request does not include an Accept-Encoding field, and if the "identity" content-coding is unavailable, 084 * then content-codings commonly understood by HTTP/1.0 clients (i.e.,"gzip" and "compress") are preferred; some older 085 * clients improperly display messages sent with other content-codings. 086 * The server might also make this decision based on information about the particular user-agent or client. 087 * 088 * <p> 089 * Note: Most HTTP/1.0 applications do not recognize or obey qvalues associated with content-codings. 090 * This means that qvalues will not work and are not permitted with x-gzip or x-compress. 091 * 092 * <ul class='seealso'> 093 * <li class='extlink'>{@doc ExtRFC2616} 094 * </ul> 095 */ 096@Header("Accept-Encoding") 097public class AcceptEncoding extends BasicStringRangeArrayHeader { 098 099 private static final long serialVersionUID = 1L; 100 101 private static final Cache<String,AcceptEncoding> CACHE = new Cache<>(NOCACHE, CACHE_MAX_SIZE); 102 103 /** 104 * Returns a parsed and cached header. 105 * 106 * @param value 107 * The header value. 108 * @return A cached {@link AcceptCharset} object. 109 */ 110 public static AcceptEncoding of(String value) { 111 if (value == null) 112 return null; 113 AcceptEncoding x = CACHE.get(value); 114 if (x == null) 115 x = CACHE.put(value, new AcceptEncoding(value)); 116 return x; 117 } 118 119 /** 120 * Convenience creator. 121 * 122 * @param value 123 * The header value. 124 * <br>Can be any of the following: 125 * <ul> 126 * <li>{@link String} - Converted using {@link StringRanges#of(String)}. 127 * <li><c>StringRange[]</c> - Left as-is. 128 * <li>Anything else - Converted to <c>String</c> then parsed. 129 * </ul> 130 * @return A new {@link AcceptEncoding} object. 131 */ 132 public static AcceptEncoding of(Object value) { 133 if (value == null) 134 return null; 135 return new AcceptEncoding(value); 136 } 137 138 /** 139 * Convenience creator using supplier. 140 * 141 * <p> 142 * Header value is re-evaluated on each call to {@link #getValue()}. 143 * 144 * @param value 145 * The header value supplier. 146 * <br>Can be any of the following: 147 * <ul> 148 * <li>{@link String} - Converted using {@link StringRanges#of(String)}. 149 * <li><c>StringRange[]</c> - Left as-is. 150 * <li>Anything else - Converted to <c>String</c> then parsed. 151 * </ul> 152 * @return A new {@link AcceptEncoding} object. 153 */ 154 public static AcceptEncoding of(Supplier<?> value) { 155 if (value == null) 156 return null; 157 return new AcceptEncoding(value); 158 } 159 160 /** 161 * Constructor 162 * 163 * @param value 164 * The header value. 165 * <br>Can be any of the following: 166 * <ul> 167 * <li>{@link String} - Converted using {@link StringRanges#of(String)}. 168 * <li><c>StringRange[]</c> - Left as-is. 169 * <li>Anything else - Converted to <c>String</c> then parsed. 170 * <li>A {@link Supplier} of anything on this list. 171 * </ul> 172 */ 173 public AcceptEncoding(Object value) { 174 super("Accept-Encoding", value); 175 } 176 177 /** 178 * Constructor 179 * 180 * @param value 181 * The header value. 182 */ 183 public AcceptEncoding(String value) { 184 this((Object)value); 185 } 186}