com.opensymphony.oscache.web.filter
Class CacheFilter

java.lang.Object
  com.opensymphony.oscache.web.filter.CacheFilter

All Implemented Interfaces:

javax.servlet.Filter

public class CacheFilter

extends java.lang.Object

implements javax.servlet.Filter

CacheFilter is a filter that allows for server-side caching of post-processed servlet content.

It also gives great programatic control over refreshing, flushing and updating the cache.

Version:

$Revision: 1.4.2.2 $

Author:

Serge Knystautas, Mike Cannon-Brookes

Field Summary

static java.lang.String	HEADER_ACCEPT_ENCODING
static java.lang.String	HEADER_CACHE_CONTROL
static java.lang.String	HEADER_CONTENT_ENCODING
static java.lang.String	HEADER_CONTENT_TYPE
static java.lang.String	HEADER_EXPIRES
static java.lang.String	HEADER_IF_MODIFIED_SINCE
static java.lang.String	HEADER_LAST_MODIFIED

Constructor Summary

CacheFilter()

Method Summary

void	destroy() Filter clean-up
void	doFilter(javax.servlet.ServletRequest request, javax.servlet.ServletResponse response, javax.servlet.FilterChain chain) The doFilter call caches the response by wrapping the HttpServletResponse object so that the output stream can be caught.
void	init(javax.servlet.FilterConfig filterConfig) Initialize the filter.

Methods inherited from class java.lang.Object

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

Field Detail

HEADER_LAST_MODIFIED

public static final java.lang.String HEADER_LAST_MODIFIED

See Also:

Constant Field Values

HEADER_CONTENT_TYPE

public static final java.lang.String HEADER_CONTENT_TYPE

See Also:

Constant Field Values

HEADER_CONTENT_ENCODING

public static final java.lang.String HEADER_CONTENT_ENCODING

See Also:

Constant Field Values

HEADER_EXPIRES

public static final java.lang.String HEADER_EXPIRES

See Also:

Constant Field Values

HEADER_IF_MODIFIED_SINCE

public static final java.lang.String HEADER_IF_MODIFIED_SINCE

See Also:

Constant Field Values

HEADER_CACHE_CONTROL

public static final java.lang.String HEADER_CACHE_CONTROL

See Also:

Constant Field Values

HEADER_ACCEPT_ENCODING

public static final java.lang.String HEADER_ACCEPT_ENCODING

See Also:

Constant Field Values

Constructor Detail

CacheFilter

public CacheFilter()

Method Detail

destroy

public void destroy()

Filter clean-up

Specified by:

destroy in interface javax.servlet.Filter

doFilter

public void doFilter(javax.servlet.ServletRequest request,
                     javax.servlet.ServletResponse response,
                     javax.servlet.FilterChain chain)
              throws javax.servlet.ServletException,
                     java.io.IOException

The doFilter call caches the response by wrapping the HttpServletResponse object so that the output stream can be caught. This works by splitting off the output stream into two with the SplitServletOutputStream class. One stream gets written out to the response as normal, the other is fed into a byte array inside a ResponseContent object.

Specified by:

doFilter in interface javax.servlet.Filter

Parameters:

request - The servlet request

response - The servlet response

chain - The filter chain

Throws:

javax.servlet.ServletException - IOException

java.io.IOException

init

public void init(javax.servlet.FilterConfig filterConfig)

Initialize the filter. This retrieves a ServletCacheAdministrator instance and configures the filter based on any initialization parameters.

The supported initialization parameters are:

• time - the default time (in seconds) to cache content for. The default value is 3600 seconds (one hour).
• scope - the default scope to cache content in. Acceptable values are application (default), session, request and page.

  Specified by:

  init in interface javax.servlet.Filter

  Parameters:

  filterConfig - The filter configuration