Redirect to an external URL from controller action in Spring MVC

I have noticed the following code is redirecting the User to a URL inside the project,

@RequestMapping(method = RequestMethod.POST)
public String processForm(HttpServletRequest request, LoginForm loginForm, 
                          BindingResult result, ModelMap model) 
{
    String redirectUrl = "yahoo.com";
    return "redirect:" + redirectUrl;
}

whereas, the following is redirecting properly as intended, but requires http:// or https://

@RequestMapping(method = RequestMethod.POST)
    public String processForm(HttpServletRequest request, LoginForm loginForm, 
                              BindingResult result, ModelMap model) 
    {
        String redirectUrl = "http://www.yahoo.com";
        return "redirect:" + redirectUrl;
    }

I want the redirect to always redirect to the URL specified, whether it has a valid protocol in it or not and do not want to redirect to a view. How can I do that?

Thanks,

Answer

You can do it with two ways.

First:

@RequestMapping(value = "/redirect", method = RequestMethod.GET)
public void method(HttpServletResponse httpServletResponse) {
    httpServletResponse.setHeader("Location", projectUrl);
    httpServletResponse.setStatus(302);
}

Second:

@RequestMapping(value = "/redirect", method = RequestMethod.GET)
public ModelAndView method() {
    return new ModelAndView("redirect:" + projectUrl);
}