org.apache.juneau.http.AcceptEncoding Maven / Gradle / Ivy
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package org.apache.juneau.http;
import static org.apache.juneau.http.Constants.*;
import org.apache.juneau.internal.*;
/**
* Represents a parsed Accept-Encoding HTTP request header.
*
*
* List of acceptable encodings.
*
*
Example
*
* Accept-Encoding: gzip, deflate
*
*
* RFC2616 Specification
*
* The Accept-Encoding request-header field is similar to Accept, but restricts the content-codings (section 3.5) that
* are acceptable in the response.
*
*
* Accept-Encoding = "Accept-Encoding" ":"
* 1#( codings [ ";" "q" "=" qvalue ] )
* codings = ( content-coding | "*" )
*
*
*
* Examples of its use are:
*
* Accept-Encoding: compress, gzip
* Accept-Encoding:
* Accept-Encoding: *
* Accept-Encoding: compress;q=0.5, gzip;q=1.0
* Accept-Encoding: gzip;q=1.0, identity; q=0.5, *;q=0
*
*
*
* A server tests whether a content-coding is acceptable, according to an Accept-Encoding field, using these rules:
*
* - If the content-coding is one of the content-codings listed in the Accept-Encoding field, then it is
* acceptable, unless it is accompanied by a qvalue of 0.
* (As defined in section 3.9, a qvalue of 0 means "not acceptable.")
*
- The special "*" symbol in an Accept-Encoding field matches any available content-coding not explicitly listed
* in the header field.
*
- If multiple content-codings are acceptable, then the acceptable content-coding with the highest non-zero
* qvalue is preferred.
*
- The "identity" content-coding is always acceptable, unless specifically refused because the Accept-Encoding
* field includes "identity;q=0", or because the field includes "*;q=0" and does not explicitly include the
* "identity" content-coding.
* If the Accept-Encoding field-value is empty, then only the "identity" encoding is acceptable.
*
*
*
* If an Accept-Encoding field is present in a request, and if the server cannot send a response which is acceptable
* according to the Accept-Encoding header, then the server SHOULD send an error response with the 406 (Not Acceptable)
* status code.
*
*
* If no Accept-Encoding field is present in a request, the server MAY assume that the client will accept any content
* coding.
* In this case, if "identity" is one of the available content-codings, then the server SHOULD use the "identity"
* content-coding, unless it has additional information that a different content-coding is meaningful to the client.
*
*
* Note: If the request does not include an Accept-Encoding field, and if the "identity" content-coding is unavailable,
* then content-codings commonly understood by HTTP/1.0 clients (i.e.,"gzip" and "compress") are preferred; some older
* clients improperly display messages sent with other content-codings.
* The server might also make this decision based on information about the particular user-agent or client.
*
*
* Note: Most HTTP/1.0 applications do not recognize or obey qvalues associated with content-codings.
* This means that qvalues will not work and are not permitted with x-gzip or x-compress.
*
*
Additional Information
*
*/
public final class AcceptEncoding extends HeaderRangeArray {
private static final Cache cache = new Cache(NOCACHE, CACHE_MAX_SIZE);
/**
* Returns a parsed Accept-Encoding header.
*
* @param value The Accept-Encoding header string.
* @return The parsed Accept-Encoding header, or null if the string was null.
*/
public static AcceptEncoding forString(String value) {
if (value == null)
return null;
AcceptEncoding a = cache.get(value);
if (a == null)
a = cache.put(value, new AcceptEncoding(value));
return a;
}
private AcceptEncoding(String value) {
super(value);
}
}