org.apache.juneau.http.CacheControl Maven / Gradle / Ivy
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package org.apache.juneau.http;
import org.apache.juneau.http.annotation.*;
/**
* Represents a parsed Cache-Control HTTP request header.
*
*
* Used to specify directives that must be obeyed by all caching mechanisms along the request-response chain.
*
*
Example
*
* Cache-Control: no-cache
*
*
* RFC2616 Specification
*
* The Cache-Control general-header field is used to specify directives that MUST be obeyed by all caching mechanisms
* along the request/response chain.
* The directives specify behavior intended to prevent caches from adversely interfering with the request or response.
* These directives typically override the default caching algorithms.
* Cache directives are unidirectional in that the presence of a directive in a request does not imply that the same
* directive is to be given in the response.
*
*
* Note that HTTP/1.0 caches might not implement Cache-Control and might only implement Pragma: no-cache (see section
* 14.32).
*
*
* Cache 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 cache- directive for a specific cache.
*
*
* Cache-Control = "Cache-Control" ":" 1#cache-directive
* cache-directive = cache-request-directive
* | cache-response-directive
* cache-request-directive =
* "no-cache" ; Section 14.9.1
* | "no-store" ; Section 14.9.2
* | "max-age" "=" delta-seconds ; Section 14.9.3, 14.9.4
* | "max-stale" [ "=" delta-seconds ] ; Section 14.9.3
* | "min-fresh" "=" delta-seconds ; Section 14.9.3
* | "no-transform" ; Section 14.9.5
* | "only-if-cached" ; Section 14.9.4
* | cache-extension ; Section 14.9.6
* cache-response-directive =
* "public" ; Section 14.9.1
* | "private" [ "=" <"> 1#field-name <"> ] ; Section 14.9.1
* | "no-cache" [ "=" <"> 1#field-name <"> ]; Section 14.9.1
* | "no-store" ; Section 14.9.2
* | "no-transform" ; Section 14.9.5
* | "must-revalidate" ; Section 14.9.4
* | "proxy-revalidate" ; Section 14.9.4
* | "max-age" "=" delta-seconds ; Section 14.9.3
* | "s-maxage" "=" delta-seconds ; Section 14.9.3
* | cache-extension ; Section 14.9.6
* cache-extension = token [ "=" ( token | quoted-string ) ]
*
*
*
* When a directive appears without any 1#field-name parameter, the directive applies to the entire request or response.
* When such a directive appears with a 1#field-name parameter, it applies only to the named field or fields, and not
* to the rest of the request or response. This mechanism supports extensibility; implementations of future versions
* of the HTTP protocol might apply these directives to header fields not defined in HTTP/1.1.
*
*
* The cache-control directives can be broken down into these general categories:
*
* - Restrictions on what are cacheable; these may only be imposed by the origin server.
*
- Restrictions on what may be stored by a cache; these may be imposed by either the origin server or the user
* agent.
*
- Modifications of the basic expiration mechanism; these may be imposed by either the origin server or the
* user agent.
*
- Controls over cache revalidation and reload; these may only be imposed by a user agent.
*
- Control over transformation of entities.
*
- Extensions to the caching system.
*
*
* See Also:
*
* - {@doc RFC2616}
*
*/
@Header("Cache-Control")
public final class CacheControl extends HeaderString {
/**
* Returns a parsed Cache-Control header.
*
* @param value The Cache-Control header string.
* @return The parsed Cache-Control header, or null if the string was null.
*/
public static CacheControl forString(String value) {
if (value == null)
return null;
return new CacheControl(value);
}
private CacheControl(String value) {
super(value);
}
}