how to disable web page cache throughout the servlets

Question

To no-cache web page, in the java controller servlet, I did somthing like this in a method:

public ModelAndView home(HttpServletRequest request, HttpServletResponse response) throws Exception {
    ModelAndView mav = new ModelAndView(ViewConstants.MV_MAIN_HOME);
    mav.addObject("testing", "Test this string");
    mav.addObject(request);
    response.setHeader("Cache-Control", "no-cache, no-store");
    response.setHeader("Pragma", "no-cache");
    response.setDateHeader("Expires", 0);
    return mav;
}

But this only works for a particular response object. I have many similar methods in a servlet. And I have many servlets too.

If I want to disable cache throughout the application, what should I do? (I do not want to add above code for every single response object).

Bronwyn

Answer 1

Why not do this via a filter?

A filter is an object that can transform the header and content (or both) of a request or response. 

...

The main tasks that a filter can perform are as follows:

...

• Modify the response headers and data. You do this by providing a customized version of the response.

Just register your Filter (class implementing the Filter interface) and modify your response within the doFilter method.

---

EDIT: E.g.

@WebFilter("/*")
public class NoCacheFilter implements javax.servlet.Filter {

    @Override
    public void init(final FilterConfig filterConfig) throws ServletException {
    }

    @Override
    public void doFilter(final ServletRequest servletRequest, final ServletResponse servletResponse, final FilterChain filterChain) throws IOException, ServletException {

        HttpServletRequest request = (HttpServletRequest)servletRequest;
        HttpServletResponse response = (HttpServletResponse) servletResponse;

        response.setHeader("Cache-Control", "no-cache, no-store");
        response.setHeader("Pragma", "no-cache");
        response.setDateHeader("Expires", 0);

        filterChain.doFilter(request, response);
    }

    @Override
    public void destroy() {
    }
}

Note that the @WebFilter annotation will require Servlet 3.0, otherwise you can register it via your web.xml. This path of "/*", would apply to any path of your application, but could be narrowed in scope.

Zampardi

Thanks a lot. I am wondering if all the servlets are the child classes of another servlet, can we do something in the base class? – Bronwyn

@Kurt Yes, that's object-oriented programming ;) – Zampardi