Class CacheHttpServlet

  extended by javax.servlet.GenericServlet
      extended by javax.servlet.http.HttpServlet
          extended by com.oreilly.servlet.CacheHttpServlet
All Implemented Interfaces:, javax.servlet.Servlet, javax.servlet.ServletConfig

public abstract class CacheHttpServlet
extends javax.servlet.http.HttpServlet

A superclass for HTTP servlets that wish to have their output cached and automatically resent as appropriate according to the servlet's getLastModified() method. To take advantage of this class, a servlet must:

This class uses the value returned by getLastModified() to manage an internal cache of the servlet's output. Before handling a request, this class checks the value of getLastModified(), and if the output cache is at least as current as the servlet's last modified time, the cached output is sent without calling the servlet's doGet() method.

In order to be safe, if this class detects that the servlet's query string, extra path info, or servlet path has changed, the cache is invalidated and recreated. However, this class does not invalidate the cache based on differing request headers or cookies; for servlets that vary their output based on these values (i.e. a session tracking servlet) this class should probably not be used.

No caching is performed for POST requests.

CacheHttpServletResponse and CacheServletOutputStream are helper classes to this class and should not be used directly.

This class has been built against Servlet API 2.2. Using it with previous Servlet API versions should work; using it with future API versions likely won't work.

0.93, 2004/06/25, added setCharacterEncoding() for servlets 2.4, 0.92, 2000/03/16, added synchronization blocks to make thread safe, 0.91, 1999/12/28, made support classes package protected, 0.90, 1999/12/19
Jason Hunter, Copyright © 1999
See Also:
Serialized Form

Constructor Summary
Method Summary
protected  void service(javax.servlet.http.HttpServletRequest req, javax.servlet.http.HttpServletResponse res)
Methods inherited from class javax.servlet.http.HttpServlet
doDelete, doGet, doHead, doOptions, doPost, doPut, doTrace, getLastModified, service
Methods inherited from class javax.servlet.GenericServlet
destroy, getInitParameter, getInitParameterNames, getServletConfig, getServletContext, getServletInfo, getServletName, init, init, log, log
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail


public CacheHttpServlet()
Method Detail


protected void service(javax.servlet.http.HttpServletRequest req,
                       javax.servlet.http.HttpServletResponse res)
                throws javax.servlet.ServletException,
service in class javax.servlet.http.HttpServlet