org.springframework.web.servlet.support
Class WebContentGenerator

java.lang.Object
  extended byorg.springframework.context.support.ApplicationObjectSupport
      extended byorg.springframework.web.context.support.WebApplicationObjectSupport
          extended byorg.springframework.web.servlet.support.WebContentGenerator
All Implemented Interfaces:
ApplicationContextAware
Direct Known Subclasses:
AbstractController, 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 determined via the "useExpiresHeader" and "userCacheControlHeader" properties.

Author:
Rod Johnson, Juergen Hoeller
See Also:
setUseExpiresHeader(boolean), setUseCacheControlHeader(boolean), AbstractController, WebContentInterceptor

Field Summary
static String HEADER_CACHE_CONTROL
           
static String HEADER_EXPIRES
           
static String HEADER_PRAGMA
           
static String METHOD_GET
           
static String METHOD_HEAD
           
static String METHOD_POST
           
 
Fields inherited from class org.springframework.context.support.ApplicationObjectSupport
logger
 
Constructor Summary
WebContentGenerator()
           
 
Method Summary
protected  void applyCacheSeconds(HttpServletResponse response, int seconds)
          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.
protected  void applyCacheSeconds(HttpServletResponse response, int seconds, boolean mustRevalidate)
          Apply the given cache seconds and generate respective 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.
protected  void cacheForSeconds(HttpServletResponse response, int seconds)
          Set HTTP headers to allow caching for the given number of seconds.
protected  void cacheForSeconds(HttpServletResponse response, int seconds, boolean mustRevalidate)
          Set HTTP headers to allow caching for the given number of seconds.
protected  void checkAndPrepare(HttpServletRequest request, HttpServletResponse response, boolean lastModified)
          Check and prepare the given request and response according to the settings of this generator.
protected  void checkAndPrepare(HttpServletRequest request, HttpServletResponse response, int cacheSeconds, boolean lastModified)
          Check and prepare the given request and response according to the settings of this generator.
 int getCacheSeconds()
          Return the number of seconds that content is cached.
 String[] getSupportedMethods()
          Return the HTTP methods that this content generator supports.
 boolean isRequireSession()
          Return whether a session is required to handle requests.
 boolean isUseCacheControlHeader()
          Return whether the HTTP 1.1 cache-control header is used.
 boolean isUseExpiresHeader()
          Return whether the HTTP 1.0 expires header is used.
protected  void preventCaching(HttpServletResponse response)
          Prevent the response from being cached.
 void setCacheSeconds(int seconds)
          Cache content for the given number of seconds.
 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)
          Set whether to use the HTTP 1.1 cache-control header.
 void setUseExpiresHeader(boolean useExpiresHeader)
          Set whether to use the HTTP 1.0 expires header.
 
Methods inherited from class org.springframework.web.context.support.WebApplicationObjectSupport
getServletContext, getTempDir, getWebApplicationContext, isContextRequired
 
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_HEAD

public static final String METHOD_HEAD
See Also:
Constant Field Values

METHOD_GET

public static final String METHOD_GET
See Also:
Constant Field Values

METHOD_POST

public static final String METHOD_POST
See Also:
Constant Field Values

HEADER_PRAGMA

public static final String HEADER_PRAGMA
See Also:
Constant Field Values

HEADER_EXPIRES

public static final String HEADER_EXPIRES
See Also:
Constant Field Values

HEADER_CACHE_CONTROL

public static final String HEADER_CACHE_CONTROL
See Also:
Constant Field Values
Constructor Detail

WebContentGenerator

public WebContentGenerator()
Method Detail

setSupportedMethods

public final void setSupportedMethods(String[] methods)
Set the HTTP methods that this content generator should support. Default is HEAD, GET and POST.


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.


setUseExpiresHeader

public final void setUseExpiresHeader(boolean useExpiresHeader)
Set whether to use the HTTP 1.0 expires header. Default is true.

Note: Cache headers will only get applied if caching is enabled for the current request.


isUseExpiresHeader

public final boolean isUseExpiresHeader()
Return whether the HTTP 1.0 expires header is used.


setUseCacheControlHeader

public final void setUseCacheControlHeader(boolean useCacheControlHeader)
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 for the current request.


isUseCacheControlHeader

public final boolean isUseCacheControlHeader()
Return whether the HTTP 1.1 cache-control header is used.


setCacheSeconds

public final void setCacheSeconds(int seconds)
Cache content for the given number of seconds. Default is -1, indicating no generation of cache-related headers.

Only if this is set to 0 (no cache) or a positive value (cache for this many seconds) will this class generate cache headers.

The headers can be overwritten by subclasses, before content is generated.


getCacheSeconds

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


checkAndPrepare

protected final void checkAndPrepare(HttpServletRequest request,
                                     HttpServletResponse response,
                                     boolean lastModified)
                              throws ServletException
Check and prepare the given request and response according to the settings of this generator. Checks for supported methods and a required session, and applies the number of cache seconds specified for this generator.

Parameters:
request - current HTTP request
response - current HTTP response
lastModified - if the mapped handler provides Last-Modified support
Throws:
ServletException - if the request cannot be handled because a check failed

checkAndPrepare

protected final void checkAndPrepare(HttpServletRequest request,
                                     HttpServletResponse response,
                                     int cacheSeconds,
                                     boolean lastModified)
                              throws ServletException
Check and prepare the given request and response according to the settings of this generator. Checks for supported methods and a required session, and applies the given number of cache seconds.

Parameters:
request - current HTTP request
response - current HTTP response
cacheSeconds - positive number of seconds into the future that the response should be cacheable for, 0 to prevent caching
lastModified - if the mapped handler provides Last-Modified support
Throws:
ServletException - if the request cannot be handled because a check failed

preventCaching

protected final void preventCaching(HttpServletResponse response)
Prevent the response from being cached. See www.mnot.net.cache docs.


cacheForSeconds

protected final void cacheForSeconds(HttpServletResponse response,
                                     int seconds)
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
See Also:
cacheForSeconds(javax.servlet.http.HttpServletResponse, int, boolean)

cacheForSeconds

protected final void cacheForSeconds(HttpServletResponse response,
                                     int seconds,
                                     boolean mustRevalidate)
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 - 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)

applyCacheSeconds

protected final void applyCacheSeconds(HttpServletResponse response,
                                       int seconds)
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
seconds - positive number of seconds into the future that the response should be cacheable for, 0 to prevent caching
See Also:
cacheForSeconds(javax.servlet.http.HttpServletResponse, int, boolean)

applyCacheSeconds

protected final void applyCacheSeconds(HttpServletResponse response,
                                       int seconds,
                                       boolean mustRevalidate)
Apply the given cache seconds and generate respective 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.

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


Copyright (C) 2003-2004 The Spring Framework Project.