Class Overview
javax.servlet.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 (or View
)
is still rendered. As such, this filter only saves bandwidth, not server performance.
Summary
Protected Methods |
void
|
doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain)
Same contract as for doFilter , but guaranteed to be
just invoked once per request.
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String
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generateETagHeaderValue(byte[] bytes)
Generate the ETag header value from the given response body byte array.
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boolean
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isEligibleForEtag(HttpServletRequest request, HttpServletResponse response, int responseStatusCode, byte[] responseBody)
Indicates whether the given request and response are eligible for ETag generation.
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[Expand]
Inherited Methods |
From class
org.springframework.web.filter.OncePerRequestFilter
final
void
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doFilter(ServletRequest request, ServletResponse response, FilterChain filterChain)
This doFilter implementation stores a request attribute for
"already filtered", proceeding without filtering again if the
attribute is already there.
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abstract
void
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doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain)
Same contract as for doFilter , but guaranteed to be
just invoked once per request.
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String
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getAlreadyFilteredAttributeName()
Return the name of the request attribute that identifies that a request
is already filtered.
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boolean
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shouldNotFilter(HttpServletRequest request)
Can be overridden in subclasses for custom filtering control,
returning true to avoid filtering of the given request.
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From class
org.springframework.web.filter.GenericFilterBean
final
void
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addRequiredProperty(String property)
Subclasses can invoke this method to specify that this property
(which must match a JavaBean property they expose) is mandatory,
and must be supplied as a config parameter.
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void
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afterPropertiesSet()
Calls the initFilterBean() method that might
contain custom initialization of a subclass.
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void
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destroy()
Subclasses may override this to perform custom filter shutdown.
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final
FilterConfig
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getFilterConfig()
Make the FilterConfig of this filter available, if any.
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final
String
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getFilterName()
Make the name of this filter available to subclasses.
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final
ServletContext
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getServletContext()
Make the ServletContext of this filter available to subclasses.
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final
void
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init(FilterConfig filterConfig)
Standard way of initializing this filter.
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void
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initBeanWrapper(BeanWrapper bw)
Initialize the BeanWrapper for this GenericFilterBean,
possibly with custom editors.
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void
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initFilterBean()
Subclasses may override this to perform custom initialization.
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final
void
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setBeanName(String beanName)
Stores the bean name as defined in the Spring bean factory.
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void
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setEnvironment(Environment environment)
Set the Environment that this object runs in.
Any environment set here overrides the DefaultWebEnvironment
provided by default.
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final
void
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setServletContext(ServletContext servletContext)
Stores the ServletContext that the bean factory runs in.
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From class
java.lang.Object
Object
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clone()
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boolean
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equals(Object arg0)
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void
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finalize()
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final
Class<?>
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getClass()
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int
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hashCode()
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final
void
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notify()
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final
void
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notifyAll()
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String
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toString()
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final
void
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wait()
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final
void
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wait(long arg0, int arg1)
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final
void
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wait(long arg0)
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From interface
javax.servlet.Filter
abstract
void
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destroy()
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abstract
void
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doFilter(ServletRequest arg0, ServletResponse arg1, FilterChain arg2)
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abstract
void
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init(FilterConfig arg0)
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From interface
org.springframework.beans.factory.BeanNameAware
abstract
void
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setBeanName(String name)
Set the name of the bean in the bean factory that created this bean.
|
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From interface
org.springframework.beans.factory.DisposableBean
abstract
void
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destroy()
Invoked by a BeanFactory on destruction of a singleton.
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From interface
org.springframework.beans.factory.InitializingBean
abstract
void
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afterPropertiesSet()
Invoked by a BeanFactory after it has set all bean properties supplied
(and satisfied BeanFactoryAware and ApplicationContextAware).
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From interface
org.springframework.context.EnvironmentAware
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From interface
org.springframework.web.context.ServletContextAware
abstract
void
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setServletContext(ServletContext servletContext)
Set the ServletContext that this object runs in.
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Public Constructors
public
ShallowEtagHeaderFilter
()
Protected Methods
protected
void
doFilterInternal
(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain)
Same contract as for doFilter
, but guaranteed to be
just invoked once per request. Provides HttpServletRequest and
HttpServletResponse arguments instead of the default ServletRequest
and ServletResponse ones.
protected
String
generateETagHeaderValue
(byte[] bytes)
Generate the ETag header value from the given response body byte array.
The default implementation generates an MD5 hash.
Parameters
bytes
| the response body as 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.
The default implementation returns true
for response status codes in the 2xx
series.
Parameters
request
| the HTTP request |
response
| the HTTP response |
responseStatusCode
| the HTTP response status code |
responseBody
| the response body |
Returns
true
if eligible for ETag generation; false
otherwise