Oltu Resource Server

protected void doGet(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException {
    
    try {
             // Make the OAuth Request out of this request and validate it
             // Specify where you expect OAuth access token (request header, body or query string)
            OAuthAccessResourceRequest oauthRequest = new 
                    OAuthAccessResourceRequest(request, ParameterStyle.HEADER);

             // Get the access token
            String accessToken = oauthRequest.getAccessToken();

             //... validate access token

         //if something goes wrong
    } catch(OAuthProblemException ex) {
        //build error response
            OAuthResponse oauthResponse = OAuthRSResponse
                    .errorResponse(HttpServletResponse.SC_UNAUTHORIZED)
                    .setRealm("Album Example")
                    .buildHeaderMessage();

             response.addDateHeader(OAuth.HeaderType.WWW_AUTHENTICATE, oauthResponse.getHeader(OAuth.HeaderType.WWW_AUTHENTICATE));
  
    }

}