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, AnnotationMethodHandlerAdapter, 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

See Also:

setCacheSeconds(int), setCacheControl(org.springframework.http.CacheControl), setRequireSession(boolean)

Field Summary

Fields

Modifier and Type	Field and Description
protected static String	HEADER_CACHE_CONTROL
static String	METHOD_GET HTTP method "GET"
static String	METHOD_HEAD HTTP method "HEAD"
static String	METHOD_POST HTTP method "POST"

Fields inherited from class org.springframework.context.support.ApplicationObjectSupport

logger

Constructor Summary

Constructors

Constructor and Description
WebContentGenerator() Create a new WebContentGenerator which supports HTTP methods GET, HEAD and POST by default.
WebContentGenerator(boolean restrictDefaultSupportedMethods) Create a new WebContentGenerator.
WebContentGenerator(String... supportedMethods) Create a new WebContentGenerator.

Method Summary

Modifier and Type	Method and Description
protected void	applyCacheControl(HttpServletResponse response, CacheControl cacheControl) Set the HTTP Cache-Control header according to the given settings.
protected void	applyCacheSeconds(HttpServletResponse response, int cacheSeconds) Apply the given cache seconds and generate corresponding HTTP headers, i.e.
protected void	applyCacheSeconds(HttpServletResponse response, int cacheSeconds, boolean mustRevalidate) Deprecated. as of 4.2, in favor of applyCacheControl(javax.servlet.http.HttpServletResponse, org.springframework.http.CacheControl)
protected void	cacheForSeconds(HttpServletResponse response, int seconds) Deprecated. as of 4.2, in favor of applyCacheControl(javax.servlet.http.HttpServletResponse, org.springframework.http.CacheControl)
protected void	cacheForSeconds(HttpServletResponse response, int seconds, boolean mustRevalidate) Deprecated. as of 4.2, in favor of applyCacheControl(javax.servlet.http.HttpServletResponse, org.springframework.http.CacheControl)
protected void	checkAndPrepare(HttpServletRequest request, HttpServletResponse response, boolean lastModified) Deprecated. as of 4.2, since the lastModified flag is effectively ignored, with a must-revalidate header only generated if explicitly configured
protected void	checkAndPrepare(HttpServletRequest request, HttpServletResponse response, int cacheSeconds, boolean lastModified) Deprecated. as of 4.2, since the lastModified flag is effectively ignored, with a must-revalidate header only generated if explicitly configured
protected void	checkRequest(HttpServletRequest request) Check the given request for supported methods and a required session, if any.
CacheControl	getCacheControl() Get the CacheControl instance that builds the Cache-Control HTTP response header.
int	getCacheSeconds() Return the number of seconds that content is cached.
String[]	getSupportedMethods() Return the HTTP methods that this content generator supports.
boolean	isAlwaysMustRevalidate() Deprecated. as of 4.2, in favor of getCacheControl()
boolean	isRequireSession() Return whether a session is required to handle requests.
boolean	isUseCacheControlHeader() Deprecated. as of 4.2, in favor of getCacheControl()
boolean	isUseCacheControlNoStore() Deprecated. as of 4.2, in favor of getCacheControl()
boolean	isUseExpiresHeader() Deprecated. as of 4.2, in favor of getCacheControl()
protected void	prepareResponse(HttpServletResponse response) Prepare the given response according to the settings of this generator.
protected void	preventCaching(HttpServletResponse response) Deprecated. as of 4.2, in favor of applyCacheControl(javax.servlet.http.HttpServletResponse, org.springframework.http.CacheControl)
void	setAlwaysMustRevalidate(boolean mustRevalidate) Deprecated. as of 4.2, in favor of setCacheControl(org.springframework.http.CacheControl)
void	setCacheControl(CacheControl cacheControl) Set the CacheControl instance to build the Cache-Control HTTP response header.
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
void	setRequireSession(boolean requireSession) Set whether a session should be required to handle requests.
void	setSupportedMethods(String... methods) Set the HTTP methods that this content generator should support.
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
void	setUseCacheControlNoStore(boolean useCacheControlNoStore) Deprecated. as of 4.2, in favor of setCacheControl(org.springframework.http.CacheControl)
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

Methods inherited from class org.springframework.web.context.support.WebApplicationObjectSupport

getServletContext, getTempDir, getWebApplicationContext, initApplicationContext, initServletContext, isContextRequired, setServletContext

Methods inherited from class org.springframework.context.support.ApplicationObjectSupport

getApplicationContext, getMessageSourceAccessor, initApplicationContext, requiredContextClass, setApplicationContext

Methods inherited from class java.lang.Object

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

Field Detail

METHOD_GET

public static final String METHOD_GET

HTTP method "GET"

See Also:

Constant Field Values

METHOD_HEAD

public static final String METHOD_HEAD

HTTP method "HEAD"

See Also:

Constant Field Values

METHOD_POST

public static final String METHOD_POST

HTTP method "POST"

See Also:

Constant Field Values

HEADER_CACHE_CONTROL

protected static final String HEADER_CACHE_CONTROL

See Also:

Constant Field Values

Constructor Detail

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 Detail

setSupportedMethods

public final void setSupportedMethods(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

public final String[] getSupportedMethods()

Return the HTTP methods that this content generator supports.

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(CacheControl cacheControl)

Set the CacheControl instance to build the Cache-Control HTTP response header.

Since:

4.2

getCacheControl

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:

setCacheControl(org.springframework.http.CacheControl)

getCacheSeconds

public final int getCacheSeconds()

Return the number of seconds that content is cached.

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,
                                                 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

Throws:

ServletException

See Also:

checkRequest(HttpServletRequest), prepareResponse(HttpServletResponse)

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

Throws:

ServletException

See Also:

checkRequest(HttpServletRequest), applyCacheSeconds(HttpServletResponse, int)

applyCacheSeconds

@Deprecated
protected final void applyCacheSeconds(HttpServletResponse response,
                                                   int cacheSeconds,
                                                   boolean mustRevalidate)

Deprecated. as of 4.2, in favor of applyCacheControl(javax.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(javax.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(javax.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(javax.servlet.http.HttpServletResponse, org.springframework.http.CacheControl)

Prevent the response from being cached. Only called in HTTP 1.0 compatibility mode.

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