I want to include the data from other servlet in my current servlet with slight modifications. I want to get output of other servlet as String.
Most of the solutions referred to request.getRequestDispatcher('/path/to/servlet/').include(request, response). But this is modifying the response of this servlet too. How can I get output of other servlet without modifying output of current servlet?
You can, as A4L mentions, use a wrapped output writer (or stream, if the called servlet uses that), to capture the intermediate results as a string with a StringWriter. It might look as this:
protected void doGet(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
PrintWriter out = response.getWriter();
RequestDispatcher dispatcher =
request.getRequestDispatcher("/other-servlet");
StringWriter sw = new StringWriter();
final PrintWriter pw = new PrintWriter(sw);
HttpServletResponse responseWrapper =
new HttpServletResponseWrapper(response) {
@Override
public PrintWriter getWriter() throws IOException {
return pw;
}
};
dispatcher.include(request, responseWrapper);
out.println(this + ": The other servlet also wrote: " + sw.toString());
out.close();
}
However, you should be careful about using this technique on large data, as collecting stream data in strings kills performance. If you need it to work on large responses, consider writing a decorating PrintWriter, which performs the modifications of response stream on the fly.
