Getting Request , Response & ServletContext in the Grails service class

import org.codehaus.groovy.grails.web.util.WebUtils;

Getting current request object:
def request = WebUtils.retrieveGrailsWebRequest().getCurrentRequest();

Getting response object:
def response = WebUtils.retrieveGrailsWebRequest().getCurrentResponse();

Getting servletContext object:
def servletContext = WebUtils.retrieveGrailsWebRequest().getServletContext();