Taking over for JspWriter

Question

Thanks to everyone in advance -

I have yet to find an easy way to do this but, is it possible to take over the handling of the data (headers and everything) written to JspWriter? Sort of like a liaison to manage that buffer dynamically and then control the output to JspWriter? I am running into issues with redirects where the status header is already being flushed out because of some of my includes (I think its the includes, but regardless its definitely flushing the buffer).

I am aware of setting buffer sizes etc.

I am not using a framework, just pure jsp on tomcat.

Thanks,

Sam

Answer 1

You can try writing a Filter and mapping it to intercept your JSPs:

(excerpt from web.xml)
<filter>
  <filter-name>jspFilter</filter-name>
  <filter-class>com.mypackage.JspFilter</filter-class>
</filter>
<filter-mapping>
  <filter-name>jspFilter</filter-name>
  <url-pattern>*.jsp</url-pattern>
</filter-mapping>

In your doFilter() method implementation you can wrap the servlet response into your own by extending HttpServletResponseWrapper and overriding its getWriter() / getOutputStream() methods to use StringWriter to buffer the response. After you invoke doFilter() method and it returns (or throws an exception) you can do whatever you want with the buffered response - print it, redirect to another page, what have you.