Grails how to change the current locale

How can I change the current locale ?

• I tried to put controller/action?lang=de but my locale is still en_US

• I tried to override the value using this piece of code:

  def key = "org.springframework.web.servlet.DispatcherServlet.LOCALE_RESOLVER"
  def localeResolver = request.getAttribute(key)
  localeResolver.setLocale(request, response, new Locale("de","DE"))
  

Nothing changed.

• I tried to override the value using this piece of code:

  import org.springframework.web.servlet.support.RequestContextUtils as RCU;
  RCU.getLocaleResolver(request).setLocale(request, response, new Locale("de","DE"))
  

And... nothing happened. i still got my locale set to en_US.

Any idea to change the locale ?