org.apache.juneau.http

Class Pragma

java.lang.Object

org.apache.juneau.http.HeaderString

org.apache.juneau.http.Pragma

public final class Pragma
extends HeaderString

Represents a parsed Pragma HTTP request/response header.

Implementation-specific fields that may have various effects anywhere along the request-response chain.

Example

Pragma: no-cache

RFC2616 Specification

The Pragma general-header field is used to include implementation- specific directives that might apply to any recipient along the request/response chain. All pragma directives specify optional behavior from the viewpoint of the protocol; however, some systems MAY require that behavior be consistent with the directives.

Pragma = "Pragma" ":" 1#pragma-directive pragma-directive = "no-cache" | extension-pragma extension-pragma = token [ "=" ( token | quoted-string ) ]

When the no-cache directive is present in a request message, an application SHOULD forward the request toward the origin server even if it has a cached copy of what is being requested. This pragma directive has the same semantics as the no-cache cache-directive (see section 14.9) and is defined here for backward compatibility with HTTP/1.0. Clients SHOULD include both header fields when a no-cache request is sent to a server not known to be HTTP/1.1 compliant.

Pragma directives MUST be passed through by a proxy or gateway application, regardless of their significance to that application, since the directives might be applicable to all recipients along the request/response chain. It is not possible to specify a pragma for a specific recipient; however, any pragma directive not relevant to a recipient SHOULD be ignored by that recipient.

HTTP/1.1 caches SHOULD treat "Pragma: no-cache" as if the client had sent "Cache-Control: no-cache". No new Pragma directives will be defined in HTTP.

Note: because the meaning of "Pragma: no-cache as a response header field is not actually specified, it does not provide a reliable replacement for "Cache-Control: no-cache" in a response.

See Also:

• Hypertext Transfer Protocol -- HTTP/1.1

Method Summary

Modifier and Type	Method and Description
static Pragma	forString(String value) Returns a parsed Pragma header.

Methods inherited from class org.apache.juneau.http.HeaderString

asString, eq, eqIC, toString

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Method Detail

forString

public static Pragma forString(String value)

Returns a parsed Pragma header.

Parameters:

value - The Pragma header string.

Returns:

The parsed Pragma header, or null if the string was null.