LoginActivity.java

package com.bourke.finch;

import android.content.Context;
import android.content.Intent;
import android.content.SharedPreferences;

import android.net.Uri;

import android.os.AsyncTask;
import android.os.Bundle;

import android.util.Log;

import android.view.View;

import android.widget.Toast;

import com.actionbarsherlock.app.SherlockFragmentActivity;

import com.bourke.finch.common.Constants;
import com.bourke.finch.common.FinchTwitterFactory;

import twitter4j.auth.AccessToken;
import twitter4j.auth.RequestToken;

import twitter4j.Twitter;

import twitter4j.TwitterException;

public class LoginActivity extends SherlockFragmentActivity {

    private static final String TAG = "Finch/LoginActivity";

    private Context mContext;

    private Twitter mTwitter;

	private RequestToken mReqToken;

    @Override
    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        mContext = getApplicationContext();

        setContentView(R.layout.login);
        getSupportActionBar().hide();

		/* Load the twitter4j helper */
        mTwitter = FinchTwitterFactory.getInstance(mContext).getTwitter();
    }

	@Override
	protected void onNewIntent(Intent intent) {
		super.onNewIntent(intent);

		Uri uri = intent.getData();
        if (uri != null &&
                uri.toString().startsWith(Constants.CALLBACK_URL)) {
            new HandleAuthTask(uri).execute();
        }
	}

    public void loginUser(View view) {
        new RequestAuthTask().execute();
    }

    private class RequestAuthTask extends AsyncTask<String, String, String> {

        @Override
        protected void onPreExecute() {
        }

        @Override
        protected String doInBackground(String... urls) {

            String authUrl = "";
            try {
                Log.i(TAG, "Request App Authentication");
                mReqToken = mTwitter.getOAuthRequestToken(
                        Constants.CALLBACK_URL);
                authUrl = mReqToken.getAuthenticationURL();

            } catch (TwitterException e) {
                e.printStackTrace();
            }
            return authUrl;
        }

        @Override
        protected void onPostExecute(String result) {
            if (!result.equals("")) {
                startActivity(new Intent(Intent.ACTION_VIEW,
                            Uri.parse(result)));
            }
        }
    }

    private class HandleAuthTask extends AsyncTask<Void, Void, Void> {

        private Uri mUri;
        private AccessToken mAccessToken;

        public HandleAuthTask(Uri uri) {
            mUri = uri;
            mAccessToken = null;
        }

        @Override
        protected void onPreExecute() {
        }

        @Override
        protected Void doInBackground(Void... params) {

            try {
                /* Authorise twitter client with user credentials */
                String oauthVerifier = mUri.getQueryParameter(
                        "oauth_verifier");
                mAccessToken = mTwitter.getOAuthAccessToken(mReqToken,
                        oauthVerifier);
            } catch (TwitterException e) {
                e.printStackTrace();
            }
            return null;
        }

        @Override
        protected void onPostExecute(Void result) {
            if (mAccessToken == null) {
                return;
            }

            mTwitter.setOAuthAccessToken(mAccessToken);

            /* Save creds to preferences for future use */
            String token = mAccessToken.getToken();
            String secret = mAccessToken.getTokenSecret();
            SharedPreferences twitterPrefs = getSharedPreferences(
                    Constants.PREF_TOKEN_DATA, MODE_PRIVATE);
            SharedPreferences.Editor editor = twitterPrefs.edit();
            editor.putString(Constants.PREF_ACCESS_TOKEN, token);
            editor.putString(Constants.PREF_ACCESS_TOKEN_SECRET,
                    secret);
            editor.commit();

            Toast.makeText(mContext, "Logged In", Toast.LENGTH_SHORT).show();

            startActivity(new Intent(mContext, MainActivity.class));
        }
    }
}