I implemented rest web services with Spring. When I deployed it in Eclipse as a Spring Boot Application, it works. However when I deployed it in Tomcat 7 on the same machine, it does not work. The error message is as follows:
XMLHttpRequest cannot load http://localhost:8080/ristoreService/oauth/token. Response to preflight request doesn't pass access control check: No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'http://127.0.0.1:8081' is therefore not allowed access.
My CORS filter looks like this:
@Component
@Order(Ordered.HIGHEST_PRECEDENCE)
public class CORSFilter implements Filter {
    @Override
    public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) throws IOException, ServletException {
        HttpServletRequest request = (HttpServletRequest) req;
        HttpServletResponse response = (HttpServletResponse) res;
        response.setHeader("Access-Control-Allow-Origin", "http://127.0.0.1:8081");
        response.setHeader("Access-Control-Allow-Credentials", "true");
        response.setHeader("Access-Control-Allow-Methods", "POST, GET, OPTIONS, DELETE");
        response.setHeader("Access-Control-Max-Age", "3600");
        response.setHeader("Access-Control-Allow-Headers", "Content-Type, Accept, X-Requested-With, remember-me, "
                + "Origin,Access-Control-Request-Method, Access-Control-Request-Headers, Authorization");
        if ("OPTIONS".equalsIgnoreCase(request.getMethod())) {
            response.setStatus(HttpServletResponse.SC_OK);
        } else {
            chain.doFilter(req, res);
        }
    }
If I comment out response.setHeader("Access-Control-Allow-Origin", "http://127.0.0.1:8081");, I still get the same error. It wouldn't work without this line even if I deploy in Eclipse. Why does it act differently being deployed under different environment on the same ip?
EDIT:
I tested the url http://localhost:8080/ristoreService/oauth/tokenwith rest client tester "CocoaRestClient" and got 404.  So I made up a url which apparently does not exist http://localhost:8080/xxxxx and run it in UI (angularjs) and again got the CORS error. I think the error is kind of misleading, it is after all a 404. But why does it complain not found when the war was deployed successfully with the name ristoreService.war under webapps in Tomcat? 
 
     
    