Facebook4J support for exchanging access-tokens - facebook

Question

I'm looking for a way to exchange short-lived access tokens for long-lived access tokens in our backend as described by Facebook here. How to do this with facebook4j?

Answer 1

I have done something like this to exchange old token for new token:
private AccessToken refreshToken(Facebook facebook, AccessToken currentToken) throws Exception {
String clientId = configuration.getString(ConfigurationKeys.SOCIAL_FACEBOOK_CLIENTID);
String clientSecret = configuration.getString(ConfigurationKeys.SOCIAL_FACEBOOK_CLIENTSECRET);
Map<String, String> params = new HashMap<String, String>();
params.put("client_id", clientId);
params.put("client_secret", clientSecret);
params.put("grant_type", "fb_exchange_token");
params.put("fb_exchange_token", currentToken.getToken());
RawAPIResponse apiResponse = facebook.callGetAPI("/oauth/access_token", params);
String response = apiResponse.asString();
AccessToken newAccessToken = new AccessToken(response);
facebook.setOAuthAccessToken(newAccessToken);
return newAccessToken;
}
I think this can be done after each login so the access token is refreshed even if it still valid - you will just get newer token with 60 days of validity.
What do you think?

Answer 2

I am extending the Facebook class. The method they provided don't work. So I wrote another function which does gives a long lived token but it's somehow invalid ( I tried testing the new token with token_debug and tried to generate client_code with it)! I will update you if I get to work it out. If you can solve it, please update me.
Please remember I didn't clean up the code as I am still writing on it.
public function GetExtendedAccessToken()
{
//global $CONFIGURATIONS;
//$info=$this->api($path,'GET',$args);//doesn't work as api overrides method to post
$string=file_get_contents("https://graph.facebook.com/oauth/access_token?client_id=".$this->getAppId()
."&client_secret=".$this->getAppSecret()
."&fb_exchange_token=".$this->getAccessToken()
."&grant_type=fb_exchange_token"
."&redirect_uri=".$redirectUri);
var_dump($string);
$tokenInfo=explode('&',$string);
$exAccessToken=str_replace('access_token=', '', $tokenInfo[0]);
$expiresAt=str_replace('expires=', '', $tokenInfo[1]);
echo "expires in ". (time()-$expiresAt);
var_dump($exAccessToken);
return $exAccessToken;
}
It works now. Some times I get an error for not providing redirect_uri.