Package org.apache.juneau.http.header

Class Pragma

java.lang.Object
org.apache.juneau.http.header.BasicHeader
org.apache.juneau.http.header.BasicStringHeader
org.apache.juneau.http.header.Pragma
All Implemented Interfaces:
Serializable, Cloneable, Header, NameValuePair
@Header("Pragma") public class Pragma extends BasicStringHeader
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:

  • Constructor Details

    • Pragma

      public Pragma(String value)
      Constructor.
      Parameters:
      value - The header value.
      Can be null.

    • Pragma

      public Pragma(Supplier<String> value)
      Constructor with delayed value.

      Header value is re-evaluated on each call to BasicStringHeader.getValue().

      Parameters:
      value - The supplier of the header value.
      Can be null.

  • Method Details

    • of

      public static Pragma of(String value)
      Static creator.
      Parameters:
      value - The header value.
      Can be null.
      Returns:
      A new header bean, or null if the value is null.

    • of

      public static Pragma of(Supplier<String> value)
      Static creator with delayed value.

      Header value is re-evaluated on each call to BasicStringHeader.getValue().

      Parameters:
      value - The supplier of the header value.
      Can be null.
      Returns:
      A new header bean, or null if the value is null.