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Google API Authorization Using Scribe OAuth Java Library

I am trying to make a Java class which would call upon Google's API to recreate an access token to a user's account with new permissions/larger scope. This class is to be instantiated by a Java servlet I had created. I want a function within that class to return a new access token. For this class to do that, I am using the Scribe library.
In Scribe's quick guide, there are two steps which concern me and have me stumped:
Step Three: Making the user validate your request token
Let’s help your users authorize your app to do the OAuth calls. For
this you need to redirect them to the following URL:
String authUrl = service.getAuthorizationUrl(requestToken);
After this either the user will get a verifier code (if this is an OOB
request) or you’ll receive a redirect from Twitter with the verifier
and the requestToken on it (if you provided a callbackUrl)
Step Four: Get the access Token
Now that you have (somehow) the verifier, you need to exchange your
requestToken and verifier for an accessToken which is the one used to
sign requests.
Verifier v = new Verifier("verifier you got from the user");
Token accessToken = service.getAccessToken(requestToken, v); // the requestToken you had from step 2
It does not seem to specify how to get that verifier from the user. How am I supposed to do that? How do I redirect my user to the authURL, and how do I get it to send its verifier back to this class of mine, which initiated the request to begin with?
If this is unclear, let me structure the question differently, taking Scribe out of the equation: To get an authorization code from Google (which would be used to then get a refresh token and access token), I would execute the following URL connection from within the servlet (yes, I've tried to answer this problem without the Scribe library, and still can't figure it out):
URL authURL = new URL("https://accounts.google.com/o/oauth2/auth");
HttpsURLConnection authCon = (HttpsURLConnection) authURL.openConnection();
authCon.setRequestMethod("GET");
authCon.setDoOutput(false);
authCon.setConnectTimeout(100000);
authCon.setRequestProperty("response_type", "code");
authCon.setRequestProperty("client_id", CLIENT_ID);
authCon.setRequestProperty("redirect_uri",
"http://**************.com/parseAuth/");
authCon.setRequestProperty("scope", convertToCommaDelimited(scopes));
authCon.setRequestProperty("state", csrfSec);
authCon.setRequestProperty("access_type", "offline");
authCon.setRequestProperty("approval_prompt", "auto");
authCon.setRequestProperty("include_granted_scopes", "true");
What has me stuck is what I should be putting for the redirect URI. After getting the user's approval for the new scope, this authorization URL would return an authorization code to the redirect URI, and seemingly nothing to whatever called it. (Am I correct in this?) So if I have another servlet as the redirect URI to parse/extract the authorization code from the response, how in the world do I get that authorization code back to my first, initial servlet? It seems to me that there is no way to have it give back the value to the servlet, in the same position of the code from which the URL was called. It looks like the function has to end there, and all new action must take place within that new servlet. But if that is the case, and I send that auth code to Google's API which would send back a refresh token and access token to ANOTHER servlet I would make to be its redirect URI, how do I possibly get that information back to what it is which called the initial servlet to begin with? That seems to be the same problem at its core, with the problem I am having with Scribe.
I've been stuck on this for many hours, and can't seem to figure out what it is I am supposed to do. I feel like I am missing some key concept, element, or step. I need this clarified. If it is at all relevant, my servlet is hosted on a Jboss application server on OpenShift.

Using Scribe library for Oauth in Twitter with callback url

I am implementing twitter in my application using scribe.
After the user authenticate my app and is redirected to new url,
I got the oauth_token and oauth_verifier but could not figure out how to generate oauth_token and oauth_secret from it.
Kindly resolve the issue and thank you in advance!!!

I've solved the problem just make a new service builder(as in the example) in the redirected page and use the oauth_token and oauth_verifier u'll get when u will be redirected to new page like this
Token requestToken = new Token(request.getParameter("oauth_token"),request.getParameter("oauth_verifier"));
Verifier verifier = new Verifier(request.getParameter("oauth_verifier"));
rest is same as in example.

See the Twitter example.
The oauth token and verifier should be what you need to request an access token and access protected resources.

Salesforce OAuth Access_Token null?

I am trying to implement the rest api sample given in the salesforce site link below.
http://wiki.developerforce.com/page/Getting_Started_with_the_Force.com_REST_API
I have set up project as said in the link, but when I am executing the project I am getting an error as "Error - no access token". When I do debug, I came to know that the variable accessToken is null.
String accessToken = (String)
request.getSession().getAttribute("ACCESS_TOKEN");
I am bit confused about this problem.
Please help me in this regard.

It seems you are missing this part in your code:
// Set a session attribute so that other servlets can get the
// access token
request.getSession().setAttribute(ACCESS_TOKEN, accessToken);
// We also get the instance URL from the OAuth response, so set it
// in the session too
request.getSession().setAttribute(INSTANCE_URL, instanceUrl);

How to retrieve home timeline from twitter in the form of .xml or JSON using java?

I want to get a home timeline from twitter and I was able to get the home timeline using twitter4j and oauth authentication method
ConfigurationBuilder confBuilder = new ConfigurationBuilder();
confBuilder.setOAuthAccessToken(accessToken.getToken())
.setOAuthAccessTokenSecret(accessToken.getTokenSecret())
.setOAuthConsumerKey(key)
.setOAuthConsumerSecret(secret);
Twitter twit = new TwitterFactory(confBuilder.build()).getInstance();
User user = twitter.verifyCredentials();
List<Status> statuses = twitter.getHomeTimeline();
but the result is not in the form of .xml or JSON. i also tried
WebResource resource = client.resource("https://api.twitter.com/1/statuses/user_timeline.json");
but all I get is GET https://api.twitter.com/1/statuses/user_timeline.json returned a response status of 401 Unauthorized
I googled many times but I just cant get it right. Please I need a sample java code of how to do it. Complete code that can run right away would be really helpful as I got a lot of partially coded program and just couldnt get it to work. thank you in advance

OK, so after looking at the release notes for the 2.2.x versions, it appears there is a way to get the JSON representation from Twitter4J, but it's disabled by default since it uses some extra memory.
So, you need to:
Enable the JSONStore using the jsonStoreEnabled config option
Get the JSON representation of a request using the getRawJson method
Sorry there's no code example, I haven't tried it myself.

401 Unauthorized:
Authentication credentials were missing or incorrect.
You need to authenticate before you perform the query.

Invalid parameter exception on client.auth_getSession() in Facebook java API

I want to connect to a my facebook application using the facebook java api 2.1.1(http://code.google.com/p/facebook-java-api/). My application is in "Desktop" mode so I should be able to access it outside of a web application. I have not defined any callback url for it as well. My code looks something like this.
FacebookJsonRestClient client = new FacebookJsonRestClient( FB_APP_API_KEY, FB_APP_SECRET );
String token = client.auth_createToken();
HttpClient http = new HttpClient();
http.setParams(new HttpClientParams());
http.setState(new HttpState());
final String LOGIN = "https://login.facebook.com/login.php";
GetMethod get = new GetMethod(LOGIN + "?api_key=" + FB_APP_API_KEY + "&v=1.0&auth_token=" + token );
http.executeMethod(get);
PostMethod post = new PostMethod(LOGIN);
post.addParameter(new NameValuePair("api_key", FB_APP_API_KEY));
post.addParameter(new NameValuePair("v", "1.0"));
post.addParameter(new NameValuePair("auth_token", token));
post.addParameter(new NameValuePair("email", "my-email"));
post.addParameter(new NameValuePair("pass", "my-password"));
http.executeMethod(post);
String session = client.auth_getSession(token);
However instead of returning the session the API throws an exception:
com.google.code.facebookapi.FacebookException: Invalid parameter
at com.google.code.facebookapi.FacebookJsonRestClient.parseCallResult(FacebookJsonRestClient.java:354)
at com.google.code.facebookapi.ExtensibleClient.callMethod(ExtensibleClient.java:535)
at com.google.code.facebookapi.ExtensibleClient.callMethod(ExtensibleClient.java:472)
at com.google.code.facebookapi.FacebookJsonRestClient.auth_getSession(FacebookJsonRestClient.java:278)
Can anyone please tell me whats wrong with this code? And what is the correct way to access a facebook application in desktop mode using the java api (v. 2.1.1).
Thanks for your help.
Regards
Nabeel Mukhtar

As far as I understand FB's API, you're not supposed to provide username and password manually but instead let the user input them manually and then allow the Facebook Login to redirect the user back to your application. This means that instead of providing "email" and "pass" you provide "next" and "cancel" URL:s instead.
This is purely a security feature of FB API and while the theory behind it is alright, the execution is far from optimal.

See this discussion thread on the Google Code site. There's a link in the that thread to a wiki page which explains how to do desktop auth.