org.weborganic.bastille.cache.filter
Class StaticCachingFilter

java.lang.Object
  org.weborganic.bastille.cache.filter.CachingFilterBase
      org.weborganic.bastille.cache.filter.StaticCachingFilter

All Implemented Interfaces:

javax.servlet.Filter, CachingFilter

public final class StaticCachingFilter
extends CachingFilterBase
implements CachingFilter

A caching filter for static resources such as scripts, images, styles, etc..

This filter is designed to be used for URIs which map directly to a file on the server as it will check whether the file has been changed and update the cache accordingly. These resources are typically served by the default Servlet on the Web container.

GZip compression

This filter will automatically compress resources such as styles and scripts while leaving images uncompressed. This is done based on the media type of the resource.

If this use agent does not support GZip encoding, the resource is served uncompressed.

Cache Key

The key for each resource is the path component of the URI. The scheme, host port, query string and fragment are ignored. The HTTP method is also ignored, so that GET and POST methods are equivalent.

Field Summary

static String	DEFAULT_CACHE_CONTROL The default cache control to use.
static String	DEFAULT_CACHE_NAME The default of the cache to use.
static long	DEFAULT_FILESIZE_THRESHOLD The default file size threshold.

Constructor Summary

StaticCachingFilter()

Method Summary

String	calculateKey(javax.servlet.http.HttpServletRequest req) Returns the key for this cache.
void	destroy()
CacheManager	getCacheManager() Returns the CacheManager for this caching filter.
String	getDefaultCacheName() Returns the default name for the cache managed by the filter.
CachedResource	getResource(javax.servlet.http.HttpServletRequest req, javax.servlet.http.HttpServletResponse res, javax.servlet.FilterChain chain) Get the requested resource either from the cache or by invoking the page directly.
void	init(javax.servlet.FilterConfig config) Initialises blockingCache to use.
boolean	isCacheable(javax.servlet.http.HttpServletRequest req) Always return true unless the "berlioz-cache" parameter is set to "false" or the file is too large or does not exist.
void	writeResponse(javax.servlet.http.HttpServletRequest req, javax.servlet.http.HttpServletResponse res, CachedResource resource) Writes the response from a PageInfo object.

Methods inherited from class org.weborganic.bastille.cache.filter.CachingFilterBase

doFilter, doFilter, writeContent

Methods inherited from class java.lang.Object

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

Field Detail

DEFAULT_CACHE_NAME

public static final String DEFAULT_CACHE_NAME

The default of the cache to use.

See Also:

Constant Field Values

DEFAULT_CACHE_CONTROL

public static final String DEFAULT_CACHE_CONTROL

The default cache control to use.

See Also:

Constant Field Values

DEFAULT_FILESIZE_THRESHOLD

public static final long DEFAULT_FILESIZE_THRESHOLD

The default file size threshold.

Beyond this files are not cached but served directly.

See Also:

Constant Field Values

Constructor Detail

StaticCachingFilter

public StaticCachingFilter()

Method Detail

getCacheManager

public CacheManager getCacheManager()

Description copied from interface: CachingFilter

Returns the CacheManager for this caching filter.

Specified by:

getCacheManager in interface CachingFilter

Returns:

the CacheManager to be used

getDefaultCacheName

public String getDefaultCacheName()

Description copied from interface: CachingFilter

Returns the default name for the cache managed by the filter.

This method must not return null.

Specified by:

getDefaultCacheName in interface CachingFilter

Returns:

the default name for the cache manage by the filter.

init

public void init(javax.servlet.FilterConfig config)
          throws CacheException

Description copied from class: CachingFilterBase

Initialises blockingCache to use.

The BlockingCache created by this method does not have a lock timeout set.

A timeout can be appled using blockingCache.setTimeoutMillis(int timeout) and takes effect immediately for all new requests

Specified by:

init in interface javax.servlet.Filter

Overrides:

init in class CachingFilterBase

Parameters:

config - this filter's configuration.

Throws:

CacheException - The most likely cause is that a cache has not been configured in ehcache's configuration file ehcache.xml for the filter name

destroy

public void destroy()

Specified by:

destroy in interface javax.servlet.Filter

getResource

public CachedResource getResource(javax.servlet.http.HttpServletRequest req,
                                  javax.servlet.http.HttpServletResponse res,
                                  javax.servlet.FilterChain chain)
                           throws IOException,
                                  javax.servlet.ServletException,
                                  CacheException

Get the requested resource either from the cache or by invoking the page directly. Returns a cached resource from the specified request and response.

This method may invoke the rest of the filter chain.

Specified by:

getResource in interface CachingFilter

Parameters:

req - The HTTP servlet request.

res - The HTTP servlet response.

chain - The filter chain.

Returns:

the corresponding cached resource

Throws:

IOException - Should an IO error occur

javax.servlet.ServletException - For general errors or errors while invoking the filetr chain.

CacheException - For caching-specific error.

isCacheable

public boolean isCacheable(javax.servlet.http.HttpServletRequest req)

Always return true unless the "berlioz-cache" parameter is set to "false" or the file is too large or does not exist. Indicates whether the resource from the specified request can return a cached copy.

This method may be used to determine whether of not this filter should be used for the resource. Implementations may use this method to decide whether to bypass the filter and directly invoke the rest of the filter chain.

Specified by:

isCacheable in interface CachingFilter

Parameters:

req - The HTTP servlet request.

Returns:

true if the caching filter can use a cache; false to invoke the rest of the filter chain.

writeResponse

public void writeResponse(javax.servlet.http.HttpServletRequest req,
                          javax.servlet.http.HttpServletResponse res,
                          CachedResource resource)
                   throws IOException,
                          javax.servlet.ServletException

Writes the response from a PageInfo object.

This method actually performs the conditional GET and returns 304 if not modified, short-circuiting the normal response.

Specified by:

writeResponse in interface CachingFilter

Parameters:

req - The HTTP servlet request.

res - the HTTP servlet response.

resource - The cached resource build previously.

Throws:

IOException - For I/O errors only

javax.servlet.ServletException - For all other errors.

calculateKey

public String calculateKey(javax.servlet.http.HttpServletRequest req)

Returns the key for this cache.

Specified by:

calculateKey in interface CachingFilter

Parameters:

req - the HTTP Servlet request.

Returns:

the request URI.