[java] 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,

For me works fine:

@RequestMapping (value = "/{id}", method = RequestMethod.GET)
public ResponseEntity<Object> redirectToExternalUrl() throws URISyntaxException {
    URI uri = new URI("http://www.google.com");
    HttpHeaders httpHeaders = new HttpHeaders();
    httpHeaders.setLocation(uri);
    return new ResponseEntity<>(httpHeaders, HttpStatus.SEE_OTHER);
}

You can do this in pretty concise way using ResponseEntity like this:

  @GetMapping
  ResponseEntity<Void> redirect() {
    return ResponseEntity.status(HttpStatus.FOUND)
        .location(URI.create("http://www.yahoo.com"))
        .build();
  }

You can use the RedirectView. Copied from the JavaDoc:

View that redirects to an absolute, context relative, or current request relative URL

Example:

@RequestMapping("/to-be-redirected")
public RedirectView localRedirect() {
    RedirectView redirectView = new RedirectView();
    redirectView.setUrl("http://www.yahoo.com");
    return redirectView;
}

You can also use a ResponseEntity, e.g.

@RequestMapping("/to-be-redirected")
public ResponseEntity<Object> redirectToExternalUrl() throws URISyntaxException {
    URI yahoo = new URI("http://www.yahoo.com");
    HttpHeaders httpHeaders = new HttpHeaders();
    httpHeaders.setLocation(yahoo);
    return new ResponseEntity<>(httpHeaders, HttpStatus.SEE_OTHER);
}

And of course, return redirect:http://www.yahoo.com as mentioned by others.

Another way to do it is just to use the sendRedirect method:

@RequestMapping(
    value = "/",
    method = RequestMethod.GET)
public void redirectToTwitter(HttpServletResponse httpServletResponse) throws IOException {
    httpServletResponse.sendRedirect("https://twitter.com");
}

For external url you have to use "http://www.yahoo.com" as the redirect url.

This is explained in the redirect: prefix of Spring reference documentation.

redirect:/myapp/some/resource

will redirect relative to the current Servlet context, while a name such as

redirect:http://myhost.com/some/arbitrary/path

will redirect to an absolute URL

Did you try RedirectView where you can provide the contextRelative parameter?

Looking into the actual implementation of UrlBasedViewResolver and RedirectView the redirect will always be contextRelative if your redirect target starts with /. So also sending a //yahoo.com/path/to/resource wouldn't help to get a protocol relative redirect.

So to achieve what you are trying you could do something like:

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

In short "redirect://yahoo.com" will lend you to yahoo.com.

where as "redirect:yahoo.com" will lend you your-context/yahoo.com ie for ex- localhost:8080/yahoo.com