How to prevent Grails from caching old versions of gsp file?

Question

I am making modifications to /grails-app/views/index.gsp.

When I save the file and refresh http://localhost:8080/index.gsp in Firefox, I am getting an old version of the

Answer 1

There doesn't seem to be a simple way to do this, but it's not much work. My solution subclasses the servlet that renders GSPs (and also the controller that's used for non-GSP requests).

Here's the servlet subclass:

package com.burtbeckwith;

import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.codehaus.groovy.grails.web.pages.GroovyPagesServlet;

public class CachingPageServlet extends GroovyPagesServlet {

   private static final String HEADER_PRAGMA = "Pragma";
   private static final String HEADER_EXPIRES = "Expires";
   private static final String HEADER_CACHE_CONTROL = "Cache-Control";

   @Override
   public void doPage(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
      response.setHeader(HEADER_PRAGMA, "no-cache");
      response.setDateHeader(HEADER_EXPIRES, 1L);
      response.setHeader(HEADER_CACHE_CONTROL, "no-cache");
      response.addHeader(HEADER_CACHE_CONTROL, "no-store");
      super.doPage(request, response);
   }
}

and you'll need to replace the original in web.xml (run "grails install-templates" and edit src/templates/war/web.xml):

   gsp
   com.burtbeckwith.CachingPageServlet

and you'll probably also want to do the same for Controller-based responses, so to do that use this controller subclass:

package com.burtbeckwith;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.codehaus.groovy.grails.web.servlet.mvc.SimpleGrailsController;
import org.springframework.web.servlet.ModelAndView;

public class CachingSimpleGrailsController extends SimpleGrailsController {

   private static final String HEADER_PRAGMA = "Pragma";
   private static final String HEADER_EXPIRES = "Expires";
   private static final String HEADER_CACHE_CONTROL = "Cache-Control";

   @Override
   public ModelAndView handleRequest(HttpServletRequest request, HttpServletResponse response) throws Exception {
      response.setHeader(HEADER_PRAGMA, "no-cache");
      response.setDateHeader(HEADER_EXPIRES, 1L);
      response.setHeader(HEADER_CACHE_CONTROL, "no-cache");
      response.addHeader(HEADER_CACHE_CONTROL, "no-store");
      return super.handleRequest(request, response);
   }
}

and you'll need to register it in grails-app/conf/spring/resources.groovy to override the regular Spring bean:

mainSimpleController(com.burtbeckwith.CachingSimpleGrailsController) {
   grailsApplication = ref('grailsApplication', true)
}

The shared header-setting code should probably be extracted into a utility class instead of being copy/pasted like I did here.