Package org.springframework.web.servlet.support

Class WebContentGenerator

java.lang.Object
org.springframework.context.support.ApplicationObjectSupport
org.springframework.web.context.support.WebApplicationObjectSupport
org.springframework.web.servlet.support.WebContentGenerator
All Implemented Interfaces:
Aware, ApplicationContextAware, ServletContextAware
Direct Known Subclasses:
AbstractController, AbstractHandlerMethodAdapter, ResourceHttpRequestHandler, WebContentInterceptor
public abstract class WebContentGenerator extends WebApplicationObjectSupport
Convenient superclass for any kind of web content generator, like AbstractController and WebContentInterceptor. Can also be used for custom handlers that have their own HandlerAdapter.

Supports HTTP cache control options. The usage of corresponding HTTP headers can be controlled via the "cacheSeconds" and "cacheControl" properties.

NOTE: As of Spring 4.2, this generator's default behavior changed when using only setCacheSeconds(int), sending HTTP response headers that are in line with current browsers and proxies implementations (i.e. no HTTP 1.0 headers anymore) Reverting to the previous behavior can be easily done by using one of the newly deprecated methods setUseExpiresHeader(boolean), setUseCacheControlHeader(boolean), setUseCacheControlNoStore(boolean) or setAlwaysMustRevalidate(boolean).

Author:
Rod Johnson, Juergen Hoeller, Brian Clozel, Rossen Stoyanchev
See Also:

  • Field Details

  • Constructor Details

    • WebContentGenerator

      public WebContentGenerator()
      Create a new WebContentGenerator which supports HTTP methods GET, HEAD and POST by default.

    • WebContentGenerator

      public WebContentGenerator(boolean restrictDefaultSupportedMethods)
      Create a new WebContentGenerator.
      Parameters:
      restrictDefaultSupportedMethods - true if this generator should support HTTP methods GET, HEAD and POST by default, or false if it should be unrestricted

    • WebContentGenerator

      public WebContentGenerator(String... supportedMethods)
      Create a new WebContentGenerator.
      Parameters:
      supportedMethods - the supported HTTP methods for this content generator

  • Method Details

    • setSupportedMethods

      public final void setSupportedMethods(@Nullable String... methods)
      Set the HTTP methods that this content generator should support.

      Default is GET, HEAD and POST for simple form controller types; unrestricted for general controllers and interceptors.

    • getSupportedMethods

      @Nullable public final String[] getSupportedMethods()
      Return the HTTP methods that this content generator supports.

    • getAllowHeader

      @Nullable protected String getAllowHeader()
      Return the "Allow" header value to use in response to an HTTP OPTIONS request based on the configured supported methods also automatically adding "OPTIONS" to the list even if not present as a supported method. This means subclasses don't have to explicitly list "OPTIONS" as a supported method as long as HTTP OPTIONS requests are handled before making a call to checkRequest(HttpServletRequest).
      Since:
      4.3

    • setRequireSession

      public final void setRequireSession(boolean requireSession)
      Set whether a session should be required to handle requests.

    • isRequireSession

      public final boolean isRequireSession()
      Return whether a session is required to handle requests.

    • setCacheControl

      public final void setCacheControl(@Nullable CacheControl cacheControl)
      Set the CacheControl instance to build the Cache-Control HTTP response header.
      Since:
      4.2

    • getCacheControl

      @Nullable public final CacheControl getCacheControl()
      Get the CacheControl instance that builds the Cache-Control HTTP response header.
      Since:
      4.2

    • setCacheSeconds

      public final void setCacheSeconds(int seconds)
      Cache content for the given number of seconds, by writing cache-related HTTP headers to the response:
      • seconds == -1 (default value): no generation cache-related headers
      • seconds == 0: "Cache-Control: no-store" will prevent caching
      • seconds > 0: "Cache-Control: max-age=seconds" will ask to cache content

      For more specific needs, a custom CacheControl should be used.

      See Also:

    • getCacheSeconds

      public final int getCacheSeconds()
      Return the number of seconds that content is cached.

    • setVaryByRequestHeaders

      public final void setVaryByRequestHeaders(@Nullable String... varyByRequestHeaders)
      Configure one or more request header names (e.g. "Accept-Language") to add to the "Vary" response header to inform clients that the response is subject to content negotiation and variances based on the value of the given request headers. The configured request header names are added only if not already present in the response "Vary" header.
      Parameters:
      varyByRequestHeaders - one or more request header names
      Since:
      4.3

    • getVaryByRequestHeaders

      @Nullable public final String[] getVaryByRequestHeaders()
      Return the configured request header names for the "Vary" response header.
      Since:
      4.3

    • setUseExpiresHeader

      @Deprecated public final void setUseExpiresHeader(boolean useExpiresHeader)
      Deprecated.
      as of 4.2, since going forward, the HTTP 1.1 cache-control header will be required, with the HTTP 1.0 headers disappearing
      Set whether to use the HTTP 1.0 expires header. Default is "false", as of 4.2.

      Note: Cache headers will only get applied if caching is enabled (or explicitly prevented) for the current request.

    • isUseExpiresHeader

      @Deprecated public final boolean isUseExpiresHeader()
      Deprecated.
      as of 4.2, in favor of getCacheControl()
      Return whether the HTTP 1.0 expires header is used.

    • setUseCacheControlHeader

      @Deprecated public final void setUseCacheControlHeader(boolean useCacheControlHeader)
      Deprecated.
      as of 4.2, since going forward, the HTTP 1.1 cache-control header will be required, with the HTTP 1.0 headers disappearing
      Set whether to use the HTTP 1.1 cache-control header. Default is "true".

      Note: Cache headers will only get applied if caching is enabled (or explicitly prevented) for the current request.

    • isUseCacheControlHeader

      @Deprecated public final boolean isUseCacheControlHeader()
      Deprecated.
      as of 4.2, in favor of getCacheControl()
      Return whether the HTTP 1.1 cache-control header is used.

    • setUseCacheControlNoStore

      @Deprecated public final void setUseCacheControlNoStore(boolean useCacheControlNoStore)
      Deprecated.
      as of 4.2, in favor of setCacheControl(org.springframework.http.CacheControl)
      Set whether to use the HTTP 1.1 cache-control header value "no-store" when preventing caching. Default is "true".

    • isUseCacheControlNoStore

      @Deprecated public final boolean isUseCacheControlNoStore()
      Deprecated.
      as of 4.2, in favor of getCacheControl()
      Return whether the HTTP 1.1 cache-control header value "no-store" is used.

    • setAlwaysMustRevalidate

      @Deprecated public final void setAlwaysMustRevalidate(boolean mustRevalidate)
      Deprecated.
      as of 4.2, in favor of setCacheControl(org.springframework.http.CacheControl)
      An option to add 'must-revalidate' to every Cache-Control header. This may be useful with annotated controller methods, which can programmatically do a last-modified calculation as described in WebRequest.checkNotModified(long).

      Default is "false".

    • isAlwaysMustRevalidate

      @Deprecated public final boolean isAlwaysMustRevalidate()
      Deprecated.
      as of 4.2, in favor of getCacheControl()
      Return whether 'must-revalidate' is added to every Cache-Control header.

    • checkRequest

      protected final void checkRequest(HttpServletRequest request) throws ServletException
      Check the given request for supported methods and a required session, if any.
      Parameters:
      request - current HTTP request
      Throws:
      ServletException - if the request cannot be handled because a check failed
      Since:
      4.2

    • prepareResponse

      protected final void prepareResponse(HttpServletResponse response)
      Prepare the given response according to the settings of this generator. Applies the number of cache seconds specified for this generator.
      Parameters:
      response - current HTTP response
      Since:
      4.2

    • applyCacheControl

      protected final void applyCacheControl(HttpServletResponse response, CacheControl cacheControl)
      Set the HTTP Cache-Control header according to the given settings.
      Parameters:
      response - current HTTP response
      cacheControl - the pre-configured cache control settings
      Since:
      4.2

    • applyCacheSeconds

      protected final void applyCacheSeconds(HttpServletResponse response, int cacheSeconds)
      Apply the given cache seconds and generate corresponding HTTP headers, i.e. allow caching for the given number of seconds in case of a positive value, prevent caching if given a 0 value, do nothing else. Does not tell the browser to revalidate the resource.
      Parameters:
      response - current HTTP response
      cacheSeconds - positive number of seconds into the future that the response should be cacheable for, 0 to prevent caching

    • checkAndPrepare

      @Deprecated protected final void checkAndPrepare(HttpServletRequest request, HttpServletResponse response, int cacheSeconds, boolean lastModified) throws ServletException
      Deprecated.
      as of 4.2, since the lastModified flag is effectively ignored, with a must-revalidate header only generated if explicitly configured
      Check and prepare the given request and response according to the settings of this generator.
      Throws:
      ServletException
      See Also:

    • applyCacheSeconds

      @Deprecated protected final void applyCacheSeconds(HttpServletResponse response, int cacheSeconds, boolean mustRevalidate)
      Deprecated.
      as of 4.2, in favor of applyCacheControl(jakarta.servlet.http.HttpServletResponse, org.springframework.http.CacheControl)
      Apply the given cache seconds and generate respective HTTP headers.

      That is, allow caching for the given number of seconds in the case of a positive value, prevent caching if given a 0 value, else do nothing (i.e. leave caching to the client).

      Parameters:
      response - the current HTTP response
      cacheSeconds - the (positive) number of seconds into the future that the response should be cacheable for; 0 to prevent caching; and a negative value to leave caching to the client.
      mustRevalidate - whether the client should revalidate the resource (typically only necessary for controllers with last-modified support)

    • cacheForSeconds

      @Deprecated protected final void cacheForSeconds(HttpServletResponse response, int seconds)
      Deprecated.
      as of 4.2, in favor of applyCacheControl(jakarta.servlet.http.HttpServletResponse, org.springframework.http.CacheControl)
      Set HTTP headers to allow caching for the given number of seconds. Does not tell the browser to revalidate the resource.
      Parameters:
      response - current HTTP response
      seconds - number of seconds into the future that the response should be cacheable for

    • cacheForSeconds

      @Deprecated protected final void cacheForSeconds(HttpServletResponse response, int seconds, boolean mustRevalidate)
      Deprecated.
      as of 4.2, in favor of applyCacheControl(jakarta.servlet.http.HttpServletResponse, org.springframework.http.CacheControl)
      Set HTTP headers to allow caching for the given number of seconds. Tells the browser to revalidate the resource if mustRevalidate is true.
      Parameters:
      response - the current HTTP response
      seconds - number of seconds into the future that the response should be cacheable for
      mustRevalidate - whether the client should revalidate the resource (typically only necessary for controllers with last-modified support)

    • preventCaching

      @Deprecated protected final void preventCaching(HttpServletResponse response)
      Deprecated.
      as of 4.2, in favor of applyCacheControl(jakarta.servlet.http.HttpServletResponse, org.springframework.http.CacheControl)
      Prevent the response from being cached. Only called in HTTP 1.0 compatibility mode.

      See https://www.mnot.net/cache_docs.