Authentication Example

Introduction

Some operation require that user has been authenticated with the Foursquare. Foursquare uses OAuth 2.0 to do that.

Note that you can save OAuthToken in database for the user and do not need to request it every time user accesses Foursquare.

API credentials

In order to use FoursquareApi you need API credentials. You can get these credentials by registering your client to Foursquare at https://foursquare.com/oauth/.

Code example

public class AuthenticationExample {
  
  public void authenticationRequest(HttpServletRequest request, HttpServletResponse response) {
    FoursquareApi foursquareApi = new FoursquareApi("Client ID", "Client Secret", "Callback URL");
    try {
      // First we need to redirect our user to authentication page. 
      response.sendRedirect(foursquareApi.getAuthenticationUrl());
    } catch (IOException e) {
      // TODO: Error handling
    }
  }
  
  public void handleCallback(HttpServletRequest request, HttpServletResponse response) {
    // After user has logged in and confirmed that our program may access user's Foursquare account
    // Foursquare redirects user back to callback url. 
    FoursquareApi foursquareApi = new FoursquareApi("Client ID", "Client Secret", "Callback URL");
    // Callback url contains authorization code 
    String code = request.getParameter("code");
    try {
      // finally we need to authenticate that authorization code 
      foursquareApi.authenticateCode(code);
      // ... and voilà we have a authenticated Foursquare client
    } catch (FoursquareApiException e) {
     // TODO: Error handling
    }
  }
  
}