public class ShallowEtagHeaderFilter extends OncePerRequestFilter
Filter that generates an ETag value based on the
content on the response. This ETag is compared to the If-None-Match
header of the request. If these headers are equal, the response content is
not sent, but rather a 304 "Not Modified" status instead.
Since the ETag is based on the response content, the response
(e.g. a View) is still rendered.
As such, this filter only saves bandwidth, not server performance.
ALREADY_FILTERED_SUFFIXlogger| Constructor and Description |
|---|
ShallowEtagHeaderFilter() |
| Modifier and Type | Method and Description |
|---|---|
protected void |
doFilterInternal(HttpServletRequest request,
HttpServletResponse response,
FilterChain filterChain)
Same contract as for
doFilter, but guaranteed to be
just invoked once per request within a single request thread. |
protected String |
generateETagHeaderValue(byte[] bytes)
Generate the ETag header value from the given response body byte array.
|
protected boolean |
isEligibleForEtag(HttpServletRequest request,
HttpServletResponse response,
int responseStatusCode,
byte[] responseBody)
Indicates whether the given request and response are eligible for ETag generation.
|
protected boolean |
shouldNotFilterAsyncDispatch()
The default value is "false" so that the filter may delay the generation of
an ETag until the last asynchronously dispatched thread.
|
doFilter, getAlreadyFilteredAttributeName, isAsyncDispatch, isAsyncStarted, shouldNotFilter, shouldNotFilterErrorDispatchaddRequiredProperty, afterPropertiesSet, destroy, getFilterConfig, getFilterName, getServletContext, init, initBeanWrapper, initFilterBean, setBeanName, setEnvironment, setServletContextprotected boolean shouldNotFilterAsyncDispatch()
shouldNotFilterAsyncDispatch in class OncePerRequestFilterprotected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain) throws ServletException, IOException
OncePerRequestFilterdoFilter, but guaranteed to be
just invoked once per request within a single request thread.
See OncePerRequestFilter.shouldNotFilterAsyncDispatch() for details.
Provides HttpServletRequest and HttpServletResponse arguments instead of the default ServletRequest and ServletResponse ones.
doFilterInternal in class OncePerRequestFilterServletExceptionIOExceptionprotected boolean isEligibleForEtag(HttpServletRequest request, HttpServletResponse response, int responseStatusCode, byte[] responseBody)
The default implementation returns true if all conditions match:
2xx seriesrequest - the HTTP requestresponse - the HTTP responseresponseStatusCode - the HTTP response status coderesponseBody - the response bodytrue if eligible for ETag generation; false otherwiseprotected String generateETagHeaderValue(byte[] bytes)
The default implementation generates an MD5 hash.
bytes - the response body as byte arrayDigestUtils