Package org.springframework.web.filter
Class ShallowEtagHeaderFilter
java.lang.Object
org.springframework.web.filter.GenericFilterBean
org.springframework.web.filter.OncePerRequestFilter
org.springframework.web.filter.ShallowEtagHeaderFilter
- All Implemented Interfaces:
Filter,Aware,BeanNameAware,DisposableBean,InitializingBean,EnvironmentAware,EnvironmentCapable,ServletContextAware
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.
- Since:
- 3.0
- Author:
- Arjen Poutsma, Rossen Stoyanchev, Brian Clozel, Juergen Hoeller
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Field Summary
Fields inherited from class org.springframework.web.filter.OncePerRequestFilter
ALREADY_FILTERED_SUFFIXFields inherited from class org.springframework.web.filter.GenericFilterBean
logger -
Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionstatic voiddisableContentCaching(ServletRequest request) This method can be used to suppress the content caching response wrapper of the ShallowEtagHeaderFilter.protected voiddoFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain) Same contract as fordoFilter, but guaranteed to be just invoked once per request within a single request thread.protected StringgenerateETagHeaderValue(InputStream inputStream, boolean isWeak) Generate the ETag header value from the given response body byte array.protected booleanisEligibleForEtag(HttpServletRequest request, HttpServletResponse response, int responseStatusCode, InputStream inputStream) Whether an ETag should be calculated for the given request and response exchange.booleanReturn whether the ETag value written to the response should be weak, as per RFC 7232.voidsetWriteWeakETag(boolean writeWeakETag) Set whether the ETag value written to the response should be weak, as per RFC 7232.protected booleanThe default value isfalseso that the filter may delay the generation of an ETag until the last asynchronously dispatched thread.Methods inherited from class org.springframework.web.filter.OncePerRequestFilter
doFilter, doFilterNestedErrorDispatch, getAlreadyFilteredAttributeName, isAsyncDispatch, isAsyncStarted, shouldNotFilter, shouldNotFilterErrorDispatchMethods inherited from class org.springframework.web.filter.GenericFilterBean
addRequiredProperty, afterPropertiesSet, createEnvironment, destroy, getEnvironment, getFilterConfig, getFilterName, getServletContext, init, initBeanWrapper, initFilterBean, setBeanName, setEnvironment, setServletContext
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Constructor Details
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ShallowEtagHeaderFilter
public ShallowEtagHeaderFilter()
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Method Details
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setWriteWeakETag
public void setWriteWeakETag(boolean writeWeakETag) Set whether the ETag value written to the response should be weak, as per RFC 7232.Should be configured using an
<init-param>for parameter name "writeWeakETag" in the filter definition inweb.xml.- Since:
- 4.3
- See Also:
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isWriteWeakETag
public boolean isWriteWeakETag()Return whether the ETag value written to the response should be weak, as per RFC 7232.- Since:
- 4.3
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shouldNotFilterAsyncDispatch
protected boolean shouldNotFilterAsyncDispatch()The default value isfalseso that the filter may delay the generation of an ETag until the last asynchronously dispatched thread.- Overrides:
shouldNotFilterAsyncDispatchin classOncePerRequestFilter
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doFilterInternal
protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain) throws ServletException, IOException Description copied from class:OncePerRequestFilterSame contract as fordoFilter, but guaranteed to be just invoked once per request within a single request thread. SeeOncePerRequestFilter.shouldNotFilterAsyncDispatch()for details.Provides HttpServletRequest and HttpServletResponse arguments instead of the default ServletRequest and ServletResponse ones.
- Specified by:
doFilterInternalin classOncePerRequestFilter- Throws:
ServletExceptionIOException
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isEligibleForEtag
protected boolean isEligibleForEtag(HttpServletRequest request, HttpServletResponse response, int responseStatusCode, InputStream inputStream) Whether an ETag should be calculated for the given request and response exchange. By default this istrueif all of the following match:- Response is not committed.
- Response status codes is in the
2xxseries. - Request method is a GET.
- Response Cache-Control header does not contain "no-store" (or is not present at all).
- Parameters:
request- the HTTP requestresponse- the HTTP responseresponseStatusCode- the HTTP response status codeinputStream- the response body- Returns:
trueif eligible for ETag generation,falseotherwise
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generateETagHeaderValue
protected String generateETagHeaderValue(InputStream inputStream, boolean isWeak) throws IOException Generate the ETag header value from the given response body byte array.The default implementation generates an MD5 hash.
- Parameters:
inputStream- the response body as an InputStreamisWeak- whether the generated ETag should be weak- Returns:
- the ETag header value
- Throws:
IOException- See Also:
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disableContentCaching
This method can be used to suppress the content caching response wrapper of the ShallowEtagHeaderFilter. The main reason for this is streaming scenarios which are not to be cached and do not need an eTag.Note: This method must be called before the response is written to in order for the entire response content to be written without caching.
- Since:
- 4.2
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