Package de.xima.fc.web.common.utils

Class ETagUtil

java.lang.Object

de.xima.fc.web.common.utils.ETagUtil

public final class ETagUtil
extends Object

Utility for working with the ETag HTTP caching mechanism.

Since:

7.0.5

Author:

XIMA MEDIA GmbH

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	ETagUtil.ETag	POJO models for an ETag that can be exchanged via HTTP requests for cache control etc.

Method Summary

Modifier and Type	Method	Description
static Set<ETagUtil.ETag>	getIfMatch(javax.servlet.http.HttpServletRequest request)
static Set<ETagUtil.ETag>	getIfNoneMatch(javax.servlet.http.HttpServletRequest request)
static Optional<Boolean>	isETagConditionSatisified(javax.servlet.http.HttpServletRequest request, Predicate<ETagUtil.ETag> matcher)
static boolean	respondNotModifiedIfUnchanged(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response, Predicate<ETagUtil.ETag> matcher)	Checks whether the ETag condition is satisfied.
static void	setETag(javax.servlet.http.HttpServletResponse response, ETagUtil.ETag tag)	Sets the ETag header to the given response.
static boolean	skipIfNotModified(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response, ETagUtil.ETag tag)	Checks whether the ETag condition is satisfied.

Methods inherited from class java.lang.Object

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

Method Detail

getIfMatch

public static Set<ETagUtil.ETag> getIfMatch(javax.servlet.http.HttpServletRequest request)

Parameters:

request - An HTTP servlet request.

Returns:

All ETags present in the If-Match header.

getIfNoneMatch

public static Set<ETagUtil.ETag> getIfNoneMatch(javax.servlet.http.HttpServletRequest request)

Parameters:

request - An HTTP servlet request.

Returns:

All ETags present in the If-None-Match header.

isETagConditionSatisified

public static Optional<Boolean> isETagConditionSatisified(javax.servlet.http.HttpServletRequest request,
                                                          Predicate<ETagUtil.ETag> matcher)

Parameters:

request - An HTTP servlet request.

matcher - A predicate function that is given an ETag and must return true when it matches the resource.

Returns:

true when the condition set by If-Match and If-None-Match headers in the request is fulfilled. Otherwise, returns false. When the request does not contain any such headers, returns an empty optional.

respondNotModifiedIfUnchanged

public static boolean respondNotModifiedIfUnchanged(javax.servlet.http.HttpServletRequest request,
                                                    javax.servlet.http.HttpServletResponse response,
                                                    Predicate<ETagUtil.ETag> matcher)

Checks whether the ETag condition is satisfied. If the condition is not satisfied, responds with a 304 Not Modified status code and returns true. In this case, you should abort the remainder of the request processing. If this returns false, you should process with the request as normally.

Parameters:

request - An HTTP servlet request.

response - An HTTP servlet response.

matcher - A predicate function that is given an ETag and must return true when it matches the resource.

Returns:

true the 304 Not Modified header was sent, false otherwise.

setETag

public static void setETag(javax.servlet.http.HttpServletResponse response,
                           ETagUtil.ETag tag)

Sets the ETag header to the given response.

Parameters:

response - An HTTP servlet response.

tag - The ETag to set.

skipIfNotModified

public static boolean skipIfNotModified(javax.servlet.http.HttpServletRequest request,
                                        javax.servlet.http.HttpServletResponse response,
                                        ETagUtil.ETag tag)

Checks whether the ETag condition is satisfied. If the condition is not satisfied, responds with a 304 Not Modified status code and returns true. In this case, you should abort the remainder of the request processing. Otherwise, sets the given ETag on the response. If this returns false, you should process with the request as normally.

Parameters:

request - An HTTP servlet request.

response - An HTTP servlet response.

tag - The ETag that the request should have to send the 304 Not Modified header.

Returns:

true the 304 Not Modified header was sent, false otherwise.