[java] How to set a header in an HTTP response?

I've a servlet A where I'm setting a header in the HTTP response:

public void doPost(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException {

    String userName=request.getParameter("userName");
    String newUrl = "http://somehost:port/ServletB";

    response.addHeader("REMOTE_USER", userName);

    response.sendRedirect(newUrl);
}

Now in a servlet B, I'm trying to get the header value that was set in the servlet A:

public void doPost(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException {

    String userid = request.getHeader("REMOTE_USER");
}

But here the value of userid is coming as null. Please let me know what I'm missing here.

Header fields are not copied to subsequent requests. You should use either cookie for this (addCookie method) or store "REMOTE_USER" in session (which you can obtain with getSession method).

In my Controller, I merely added an HttpServletResponse parameter and manually added the headers, no filter or intercept required and it works fine:

httpServletResponse.setHeader("Access-Control-Allow-Origin", "*");
httpServletResponse.setHeader("Access-Control-Allow-Methods", "GET, OPTIONS");
httpServletResponse.setHeader("Access-Control-Allow-Headers","Origin, X-Requested-With, Content-Type, Accept, X-Auth-Token, X-Csrf-Token, WWW-Authenticate, Authorization");
httpServletResponse.setHeader("Access-Control-Allow-Credentials", "false");
httpServletResponse.setHeader("Access-Control-Max-Age", "3600");