How to redirect in a servlet filter?

Question

I\'m trying to find a method to redirect my request from a filter to the login page but I don\'t know how to redirect from servlet. I\'ve searched but what I find is s

Answer 1

Your response object is declared as a ServletResponse. To use the sendRedirect() method, you have to cast it to HttpServletResponse. This is an extended interface that adds methods related to the HTTP protocol.

Answer 2

In Filter the response is of ServletResponse rather than HttpServletResponse. Hence do the cast to HttpServletResponse.

HttpServletResponse httpResponse = (HttpServletResponse) response;
httpResponse.sendRedirect("/login.jsp");

If using a context path:

httpResponse.sendRedirect(req.getContextPath() + "/login.jsp");

Also don't forget to call return; at the end.

Answer 3

I'm trying to find a method to redirect my request from filter to login page

Don't

You just invoke

chain.doFilter(request, response);

from filter and the normal flow will go ahead.

I don't know how to redirect from servlet

You can use

response.sendRedirect(url);

to redirect from servlet

Answer 4

If you also want to keep hash and get parameter, you can do something like this (fill redirectMap at filter init):

String uri = request.getRequestURI();

String[] uriParts = uri.split("[#?]");
String path = uriParts[0];
String rest = uri.substring(uriParts[0].length());

if(redirectMap.containsKey(path)) {
    response.sendRedirect(redirectMap.get(path) + rest);
} else {
    chain.doFilter(request, response);
}

Answer 5

Try and check of your ServletResponse response is an instanceof HttpServletResponse like so:

if (response instanceof HttpServletResponse) {
    response.sendRedirect(....);
}