Another possibility for preventing caching is to forcibly set the
last-modified date of the servlet/JSP.
You can always use the often-suggested (and well-archived) solution:
<%
response.setHeader("Pragma", "No-cache");
response.setHeader("Cache-Control", "no-cache");
response.setDateHeader("Expires",0);
%>
SnowWolf Wagner, in an article at
http://www.orionsupport.com/articles/defeatingcache.html, mentions the
following snippet as being effective as well, especially for defeating
caching proxies:
<%!
// return current time to proxy server request
public long getLastModified(HttpServletRequest request) {
return System.currentTimeMillis();
}
%>
This may aid the browsers, even without the proxies, as well.
>From: ems vasudevan <[EMAIL PROTECTED]>
>Reply-To: A mailing list about Java Server Pages specification and
>reference <[EMAIL PROTECTED]>
>To: [EMAIL PROTECTED]
>Subject: Re: How to prevent IE from cacheing a JSP page
>Date: Thu, 17 May 2001 19:02:17 -0700
>
>Try this .It will work.I have used it to prevent
>caching in JSP.
>with warm regds,
>E.M.S.vasu
>--- "Middleton, Jorge Luis" <[EMAIL PROTECTED]>
>wrote:
> > Did you try with this header?
> >
> > response.setHeader("Pragma", "No-cache");
> > --> response.setHeader("Cache-Control",
> > "no-cache");
> > response.setDateHeader("Expires",0);
> >
> > Saludos
> > Jorge Middleton
> > Argentina - Mendoza
> >
> > -----Original Message-----
> > From: Celeste Haseltine
> > [mailto:[EMAIL PROTECTED]]
> > Sent: Thursday, May 17, 2001 4:50 PM
> > To: [EMAIL PROTECTED]
> > Subject: How to prevent IE from cacheing a JSP page
> >
> >
> > I'm hoping someone out here has run into this
> > problem, and has found a way
> > to address this. I've researched this for two days,
> > and have not found a
> > solution.
> >
> > I have 2 jsp files, one that includes server side
> > JavaScript to create a
> > DHTML menu dynamically. In order for these two
> > jsp's to work properly, I
> > have to determine what JS files to "include" in the
> > JSP page based off of
> > the user's login, and I also do this dynamically.
> > Both of these files work
> > perfectly if I test my web site using Netscape, but
> > not with IE. From doing
> > some research, I have discovered that Netscape does
> > not cache pages, and
> > that I can set the expiration of a page to "0" so
> > that a particular JSP is
> > always recompiled, regardless of the date. But IE
> > does cache pages, and
> > ignores any commands to set a page's expiration to
> > 0. So if I am using
> > Netscape, both the JSP's are recompiled to include
> > their user specific JS
> > code based off of the user's login, and each user
> > get his/her specific menu
> > JS code. But in IE, the most recent JSP page on the
> > server, inclusive of
> > that page's menu specific JS code, is sent to the
> > browser, regardless of
> > what the user's login is. I've tried to work around
> > this by using the META
> > tags in my JSP files as follows:
> >
> > <head>
> > <META HTTP-EQUIV="expires" CONTENT="0">
> > <META HTTP-EQUIV="Pragma" CONTENT="no-cache">
> > </head>
> >
> > which had no effect at all on IE. I have since
> > discovered that the current
> > version of IE ignores MetaTags. So I tried to use
> > the response.setHeader
> > method in the jsp's as follows:
> >
> > <head>
> > <% response.setHeader("expires","0");
> > response.setIntHeader("expires",0);
> > response.setHeader("Pragma","no-cache");
> > %>
> > </head>
> >
> > which also doesn't work. Does anyone know how to
> > send IE a "message" via
> > the HTTP header telling it NOT to cache a jsp page,
> > and to also set the
> > expiration on a particular page to "0", which means
> > "page has immediate
> > expiration"? Or is there a way to "set" the
> > expiration of a jsp page in
> > JRUN 3.1 environment (I could not find one)? I do
> > want both of these JSP
> > pages to be "recompiled" on the server side to
> > include their menu specific
> > JS, based off of the user's login. I know that I
> > take a performance hit by
> > doing this, but since it is only two pages out of
> > 300, and it occurs as part
> > of the log in process, it's a performance hit I can
> > live with. And it beats
> > the heck out of writing 11 different JSP's, each
> > with their unique
> > respective JS menu code.
> >
> > Any advice/insight would be appreciated.
> >
> > Celeste
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