Women in Technology

Article:		Two Servlet Filters Every Web Application Should Have
Subject:		Caching saves no data
Date:		2003-11-25 21:21:41
From:		anonymous2
I cannot seem to get the caching solution to work. I believe that the ByteArrayOutputStream is not getting any data when CacheResponseWrapper wrappedResponse = new CacheResponseWrapper(response, baos); chain.doFilter(req, wrappedResponse); is executed. The file created contains no data :(. Tracing the program flow shows that both the CacheResponseWrapper and CacheResponseStream are created. I am using tomcat 4.1.27, jdk1.4.1, I have followed all the instructions, any help much appreciated!

Showing messages 1 through 6 of 6.

• Problem with the ByteArrayOutputStream ...
  2003-11-27 03:07:07  anonymous2 [View]
  
  
  Hello !
  
  I am using jboss-3.2.1_tomcat-4.1.24 Bundle ...
  
  I have exactly the same problem ...
  The ByteArrayOutputStream is still empty after the :
  chain.doFilter(req, wrappedResponse);
  
  If i try :
  System.out.println("CacheFilter : BAOS Size = " + baos.size());
  
  I get : BAOS size = 0 ...
  
  So :
  FileOutputStream fos = new FileOutputStream(file);
  fos.write(baos.toByteArray());
  
  is only creating an empty cache ...
  
  I don't know where I missed something, so if you have a clue, tell me please ^_^
  
  Thomas.
  (taimonetti@kourosivo.com)
• Problem solved ^_^
  2003-11-27 03:30:41  anonymous2 [View]
  
  
  Hello all !
  
  OK, problem solved ...
  In fact in the file web.xml :
  
  <filter-mapping>
  <filter-name>CacheFilter</filter-name>
  <url-pattern>*.jsp</url-pattern>
  </filter-mapping>
  <filter-mapping>
  <filter-name>GZIPFilter</filter-name>
  <url-pattern>*.jsp</url-pattern>
  </filter-mapping>
  
  You need to declare your CacheFilter filter-mapping before your GZIPFilter filter-mapping ...
  
  And then everything is ok :)
  
  Thanks Jayson for your filters,
  
  Thomas.
• Problem solved ^_^
  2003-12-02 15:26:36  anonymous2 [View]
  
  
  I am glad your solution worked. However I must have another issue as I don't even have the GZIPFiler enabled. I have taken everything out of the web.xml except the cache filter and still no joy.
• Problem solved
  2005-01-07 04:48:16  mcr [View]
  
  
  This also worked with Tomcat 5, but without
  requiring the clumsy empty file include:
  
  <% out.flush(); %>
• Problem solved ^_^
  2005-01-06 12:54:28  mcr [View]
  
  
  I finally solved this problem by importing an empty html file with flush=true at the very end of each cached page, as so:
  
  
• Problem solved ^_^
  2005-01-06 12:55:29  mcr [View]
  
  
  Sorry:
  
  >jsp:include page="/include/empty.html" flush="true" /<