程序包 cn.taketoday.web.servlet.filter

类 ShallowEtagHeaderFilter

java.lang.Object

cn.taketoday.web.servlet.filter.GenericFilterBean

cn.taketoday.web.servlet.filter.OncePerRequestFilter

cn.taketoday.web.servlet.filter.ShallowEtagHeaderFilter

所有已实现的接口:

cn.taketoday.beans.factory.Aware, cn.taketoday.beans.factory.BeanNameAware, cn.taketoday.beans.factory.DisposableBean, cn.taketoday.beans.factory.InitializingBean, cn.taketoday.context.EnvironmentAware, cn.taketoday.core.env.EnvironmentCapable, ServletContextAware, Filter

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.

State-changing HTTP methods and other HTTP conditional request headers such as If-Match and If-Unmodified-Since are outside the scope of this filter. Please consider using RequestContext.checkNotModified(String, long) instead.

从以下版本开始:

4.0 2022/4/9 12:10

作者:

Arjen Poutsma, Rossen Stoyanchev, Brian Clozel, Juergen Hoeller, Harry Yang

嵌套类概要

嵌套类

修饰符和类型	类	说明
private static class	ShallowEtagHeaderFilter.ConditionalContentCachingResponseWrapper	Returns the raw OutputStream, instead of the one that does caching, if isContentCachingDisabled(jakarta.servlet.http.HttpServletRequest).

字段概要

字段

修饰符和类型	字段	说明
private static final String	DIRECTIVE_NO_STORE
private static final String	STREAMING_ATTRIBUTE
private boolean	writeWeakETag

从类继承的字段 cn.taketoday.web.servlet.filter.OncePerRequestFilter

ALREADY_FILTERED_SUFFIX

从类继承的字段 cn.taketoday.web.servlet.filter.GenericFilterBean

logger

构造器概要

构造器

构造器	说明
ShallowEtagHeaderFilter()

方法概要

修饰符和类型	方法	说明
static void	disableContentCaching(RequestContext request)	This method can be used to suppress the content caching response wrapper of the ShallowEtagHeaderFilter.
static void	disableContentCaching(ServletRequest request)	This method can be used to suppress the content caching response wrapper of the ShallowEtagHeaderFilter.
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(InputStream inputStream, boolean isWeak)	Generate the ETag header value from the given response body byte array.
private static boolean	isContentCachingDisabled(HttpServletRequest request)
protected boolean	isEligibleForEtag(HttpServletRequest request, HttpServletResponse response, int responseStatusCode, InputStream inputStream)	Whether an ETag should be calculated for the given request and response exchange.
boolean	isWriteWeakETag()	Return whether the ETag value written to the response should be weak, as per RFC 7232.
void	setWriteWeakETag(boolean writeWeakETag)	Set whether the ETag value written to the response should be weak, as per RFC 7232.
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.
private void	updateResponse(HttpServletRequest request, HttpServletResponse response)

从类继承的方法 cn.taketoday.web.servlet.filter.OncePerRequestFilter

doFilter, doFilterNestedErrorDispatch, getAlreadyFilteredAttributeName, isAsyncDispatch, isAsyncStarted, shouldNotFilter, shouldNotFilterErrorDispatch

从类继承的方法 cn.taketoday.web.servlet.filter.GenericFilterBean

addRequiredProperty, afterPropertiesSet, createEnvironment, destroy, getEnvironment, getFilterConfig, getFilterName, getServletContext, init, initBeanWrapper, initFilterBean, setBeanName, setEnvironment, setServletContext

从类继承的方法 java.lang.Object

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

字段详细资料

DIRECTIVE_NO_STORE

private static final String DIRECTIVE_NO_STORE

另请参阅:

• 常量字段值

STREAMING_ATTRIBUTE

private static final String STREAMING_ATTRIBUTE

writeWeakETag

private boolean writeWeakETag

构造器详细资料

ShallowEtagHeaderFilter

public ShallowEtagHeaderFilter()

方法详细资料

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 in web.xml.

另请参阅:

• RFC 7232 section 2.3

isWriteWeakETag

public boolean isWriteWeakETag()

Return whether the ETag value written to the response should be weak, as per RFC 7232.

shouldNotFilterAsyncDispatch

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.

覆盖:

shouldNotFilterAsyncDispatch 在类中 OncePerRequestFilter

doFilterInternal

protected void doFilterInternal(HttpServletRequest request,
 HttpServletResponse response,
 FilterChain filterChain)
                         throws ServletException,
IOException

从类复制的说明: OncePerRequestFilter

Same contract as for doFilter, 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.

指定者:

doFilterInternal 在类中 OncePerRequestFilter

抛出:

ServletException

IOException

updateResponse

private void updateResponse(HttpServletRequest request,
 HttpServletResponse response)
                     throws IOException

抛出:

IOException

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 is true if all of the following match:

• Response is not committed.
• Response status codes is in the 2xx series.
• Request method is a GET.
• Response Cache-Control header does not contain "no-store" (or is not present at all).

参数:

request - the HTTP request

response - the HTTP response

responseStatusCode - the HTTP response status code

inputStream - the response body

返回:

true if eligible for ETag generation, false otherwise

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.

参数:

inputStream - the response body as an InputStream

isWeak - whether the generated ETag should be weak

返回:

the ETag header value

抛出:

IOException

另请参阅:

• DigestUtils

disableContentCaching

public static void disableContentCaching(ServletRequest request)

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.

disableContentCaching

public static void disableContentCaching(RequestContext request)

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.

isContentCachingDisabled

private static boolean isContentCachingDisabled(HttpServletRequest request)