com.oreilly.servlet
Class CacheHttpServlet

java.lang.Object
  HttpServlet
      com.oreilly.servlet.CacheHttpServlet

public abstract class CacheHttpServlet
extends 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:

• Extend CacheHttpServlet instead of HttpServlet
• Implement a getLastModified(HttpServletRequest) method as usual

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.

Version:

0.92, 00/03/16, added synchronization blocks to make thread safe, 0.91, 99/12/28, made support classes package protected, 0.90, 99/12/19

Author:

Jason Hunter, Copyright © 1999

Constructor Summary

CacheHttpServlet()

Method Summary

Methods inherited from class java.lang.Object

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

Constructor Detail

CacheHttpServlet

public CacheHttpServlet()