How can I get the HTTP status code out of a ServletResponse in a ServletFilter?

Question

I'm trying to report on every HTTP status code returned from my webapp. However the status code does not appear to be accessible via the ServletResponse, or even if I cast it to a HttpServletResponse. Is there a way to get access to this value within a ServletFilter?

Answer 1

First, you need to save the status code in an accessible place. The best to wrap the response with your implementation and keep it there:

public class StatusExposingServletResponse extends HttpServletResponseWrapper {      private int httpStatus;      public StatusExposingServletResponse(HttpServletResponse response) {         super(response);     }      @Override     public void sendError(int sc) throws IOException {         httpStatus = sc;         super.sendError(sc);     }      @Override     public void sendError(int sc, String msg) throws IOException {         httpStatus = sc;         super.sendError(sc, msg);     }       @Override     public void setStatus(int sc) {         httpStatus = sc;         super.setStatus(sc);     }      public int getStatus() {         return httpStatus;     }  } 

In order to use this wrapper, you need to add a servlet filter, were you can do your reporting:

public class StatusReportingFilter implements Filter {      public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) throws IOException, ServletException {         StatusExposingServletResponse response = new StatusExposingServletResponse((HttpServletResponse)res);         chain.doFilter(req, response);         int status = response.getStatus();         // report     }      public void init(FilterConfig config) throws ServletException {         //empty     }      public void destroy() {         // empty     }  } 

Answer 2

Since Servlet 3.0, there's a HttpServletResponse#getStatus().

So, if there's room for upgrading, upgrade to Servlet 3.0 (Tomcat 7, Glassfish 3, JBoss AS 6, etc) and you don't need a wrapper.

chain.doFilter(request, response); int status = ((HttpServletResponse) response).getStatus();