On Thu, 2014-03-13 at 17:51 -0700, Brendan Miller wrote:
> I have a filter with doFilter method like this:
>
> public void doFilter(ServletRequest request,
> ServletResponse response,
> FilterChain chain)
> throws IOException, ServletException {
> HttpServletRequest req = (HttpServletRequest) request;
> HttpServletResponse resp = (HttpServletResponse) response;
>
> resp.setHeader("Cache-Control",
> "must-revalidate, max-age=0, post-check=0,
> pre-check=0");
>
> chain.doFilter(request, response);
> }
>
> This sets the header. However, if I set the header *after* chain.doFilter,
> the header is not set. Why is this?
>
A similar question came up last week. Basically, it's because the
response has already been committed. A response becomes committed once
the 1st byte is sent back to the client -- e.g. if flush() is called or
the buffer becomes full while more response data is written.
You can search the archive for how it was resolved. Don't recall the
subject line. Sorry.
-- Tim
> public void doFilter(ServletRequest request,
> ServletResponse response,
> FilterChain chain)
> throws IOException, ServletException {
> HttpServletRequest req = (HttpServletRequest) request;
> HttpServletResponse resp = (HttpServletResponse) response;
>
> chain.doFilter(request, response);
>
> resp.setHeader("Cache-Control",
> "must-revalidate, max-age=0, post-check=0,
> pre-check=0");
> }
>
> Programmatically I can see the header is null.
>
> Has the content already been sent to the web browser after chain.doFilter?
> If so, is there a way to delay sending data to the browser? I need to
> inspect the status code in the response before setting my header (to
> prevent 404's from being cached).
>
> Thanks,
> Brendan Miller
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