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Question

For a long while I was using a login almost identical to the one found in this tutorial until I realized it was deprecated.

So like a good developer I decided to try upgrading my login to Facebook Android 3.0 SDK, but as I looked at the documentation I couldn't help but wonder why Facebook would over complicate their login when the old one worked so well.

My current code is below , but I'm a bit confused. I used to simply make an authorize request to Facebook, get some info from them, compare it to my db and if it matched up id save some info to shared prefs and open the home activity of my app. However, with the 3.0 and "sessions" I'm a bit confused:

1. Do I have to use these "sessions" in all my activities?
2. If so, do they persist throughout my app?
3. What is the point of sessions if we already have shared prefs?

The code:

import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.List;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;

import com.facebook.LoggingBehavior;
import com.facebook.Request;
import com.facebook.Response;
import com.facebook.Session;
import com.facebook.SessionState;
import com.facebook.Settings;
import com.facebook.model.GraphUser;
import com.loopj.android.http.JsonHttpResponseHandler;
import com.loopj.android.http.RequestParams;

public class FBLoginActivity extends Activity {
    private static final String URL_PREFIX_FRIENDS = "https://graph.facebook.com/me/friends?access_token=";

    private TextView textInstructionsOrLink;
    private Button buttonLoginLogout;
    private Session.StatusCallback statusCallback = new SessionStatusCallback();
 // List of additional write permissions being requested
    private static final List<String> PERMISSIONS = Arrays.asList("email","user_about_me","user_activities",
    "user_birthday","user_education_history", "user_events","user_hometown", "user_groups","user_interests","user_likes",
    "user_location","user_photos","user_work_history");

    SharedPrefs sharedprefs;
    // Request code for reauthorization requests.
    private static final int REAUTH_ACTIVITY_CODE = 100;

    // Flag to represent if we are waiting for extended permissions
    private boolean pendingAnnounce = false;
    protected String college; 

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.facebooklogin); 
        buttonLoginLogout = (Button)findViewById(R.id.buttonLoginLogout);
        textInstructionsOrLink = (TextView)findViewById(R.id.instructionsOrLink);

        Settings.addLoggingBehavior(LoggingBehavior.INCLUDE_ACCESS_TOKENS);

        Session session = Session.getActiveSession();
        if (session == null) {
            if (savedInstanceState != null) {
                session = Session.restoreSession(this, null, statusCallback, savedInstanceState);
            }
            if (session == null) {
                session = new Session(this);
            }
            Session.setActiveSession(session);
            if (session.getState().equals(SessionState.CREATED_TOKEN_LOADED)) {
                session.openForRead(new Session.OpenRequest(this).setCallback(statusCallback).setPermissions(PERMISSIONS));
            }
        }

        updateView();
    }

    @Override
    public void onStart() {
        super.onStart();
        Session.getActiveSession().addCallback(statusCallback);
    }

    @Override
    public void onStop() {
        super.onStop();
        Session.getActiveSession().removeCallback(statusCallback);
    }

    @Override
    public void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        Session.getActiveSession().onActivityResult(this, requestCode, resultCode, data);
    }

    @Override
    protected void onSaveInstanceState(Bundle outState) {
        super.onSaveInstanceState(outState);
        Session session = Session.getActiveSession();
        Session.saveSession(session, outState);
    }

    private void updateView() {
        Session session = Session.getActiveSession();
        if (session.isOpened()) {
            Log.i("permissions",session.getPermissions().toString());
            //makeLikesRequest(session);
            makeMeRequest(session);

            Log.i("token",session.getAccessToken());
            Log.i("token experation", session.getExpirationDate().toString());




            Intent i = new Intent(getApplicationContext(), FaceTestActivity.class);
            startActivity(i);
            /*buttonLoginLogout.setText(R.string.logout);
            buttonLoginLogout.setOnClickListener(new OnClickListener() {
                public void onClick(View view) { onClickLogout(); }
            });*/
        } else {
            textInstructionsOrLink.setText(R.string.instructions);
            buttonLoginLogout.setText(R.string.login);
            buttonLoginLogout.setOnClickListener(new OnClickListener() {
                public void onClick(View view) { onClickLogin(); }
            });
        }
    }

    private void onClickLogin() {
        Session session = Session.getActiveSession();
        if (!session.isOpened() && !session.isClosed()) {
            session.openForRead(new Session.OpenRequest(this).setCallback(statusCallback).setPermissions(PERMISSIONS));
        } else {

            Session.openActiveSession(this, true, statusCallback);
        }

    }

    private void onClickLogout() {
        Session session = Session.getActiveSession();
        if (!session.isClosed()) {
            session.closeAndClearTokenInformation();
        }
    }

    private class SessionStatusCallback implements Session.StatusCallback {
        @Override
        public void call(Session session, SessionState state, Exception exception) {
            updateView();
        }
    }

   /* private void makeLikesRequest(final Session session) {
        Request.Callback callback = new Request.Callback() {

            @Override
            public void onCompleted(Response response) {
                // response should have the likes

                 // If the response is successful
                if (session == Session.getActiveSession()) {

                    Log.i("likes response", response.toString());
                }

            }
        };
        Request request = new Request(session, "me/likes", null, HttpMethod.GET, callback);
        RequestAsyncTask task = new RequestAsyncTask(request);
        task.execute();
    } */


    private void makeMeRequest(final Session session) {
        // Make an API call to get user data and define a 
        // new callback to handle the response.
        Request request = Request.newMeRequest(session, 
                new Request.GraphUserCallback() {
            @Override
            public void onCompleted(GraphUser user, Response response) {
                // If the response is successful
                if (session == Session.getActiveSession()) {
                    if (user != null) {
                        // Set the id for the ProfilePictureView
                        // view that in turn displays the profile picture.
                        Log.i("user", user.toString());
                        JSONObject json = user.getInnerJSONObject();
                        Log.i("json me response", json.toString());

                        RequestParams params = new RequestParams();

                        String fb_token = session.getAccessToken().toString();
                        String fb_token_expires = session.getExpirationDate().toString();
                        Log.i("fb_token", fb_token);
                        params.put("fb_token",fb_token);
                        Log.i("fb_token_expires", fb_token_expires);
                        params.put("fb_token_expires",fb_token);



                        if(user.getBirthday() != null){
                            String birthday = user.getBirthday();
                            Log.i("birthday_1",birthday);
                            params.put("birthday", birthday);
                        }

                        if(user.getFirstName() != null){
                            String firstName = user.getFirstName();
                            Log.i("first name_2", firstName);
                            params.put("firstName", firstName);
                        }

                        if(user.getLastName() != null){
                            String lastName = user.getLastName();
                            Log.i("last name_3", lastName);
                            params.put("lastName", lastName);
                        }

                        if(user.getLink() != null){
                            String fb_link = user.getLink();
                            Log.i("fb_link_4", fb_link);
                            params.put("fb_link", fb_link);
                        }

                        if(user.getId() != null){
                            String fb_uid = user.getId();
                            Log.i("fb uid_5", fb_uid);
                            params.put("fb_uid", fb_uid);
                        }


                        if(user.getProperty("gender") != null){
                            String gender = user.getProperty("gender").toString();
                            Log.i("gender_6", gender);
                            params.put("gender", gender);
                        }

                        if(user.getProperty("email") != null){
                            String email = user.getProperty("email").toString();
                            Log.i("email_7", email);
                            params.put("email", email);
                        }


                        if(user.getProperty("verified") != null){
                            String verified = user.getProperty("verified").toString();
                            Log.i("verified_8", verified);
                            params.put("verified", verified);

                        }


                        if(user.getProperty("bio") != null){
                            String bio = user.getProperty("bio").toString();
                            Log.i("bio_9", bio);
                            params.put("bio", bio);

                        }
                        if(user.getLocation().getProperty("name") != null){

                            String location = user.getLocation().getProperty("name").toString();
                            Log.i("location_10", location);
                            params.put("location", location);

                        } 


                        //user Location
                        JSONArray education_array = (JSONArray)user.getProperty("education");
                        if (education_array.length() > 0) {
                            String education_length= String.valueOf(education_array.length());
                            Log.i("education_length",education_length);
                            ArrayList<String> collegeNames = new ArrayList<String> ();
                            for (int i=0; i < education_array.length(); i++) {
                                JSONObject edu_obj = education_array.optJSONObject(i);


                                // Add the language name to a list. Use JSON
                                // methods to get access to the name field.

                              String type = edu_obj.optString("type");
                              Log.i("type of edu", type);
                              if(type.equalsIgnoreCase("college")){
                                  JSONObject school_obj = edu_obj.optJSONObject("school");
                                  college = school_obj.optString("name");
                                  //Log.i("college",college);



                              }


                            }  
                            params.put("college", college);
                            Log.i("college", college);

                        }


                        RestClient.post(FB_LOGIN_URL, params, new JsonHttpResponseHandler() {
                            @Override
                            public void onFailure(Throwable arg0, JSONObject arg1) {
                                // TODO Auto-generated method stub
                                super.onFailure(arg0, arg1);

                                Log.i("FAILED TO LOGIN:", arg1.toString());
                                Toast.makeText(getApplicationContext(), arg1.toString() , Toast.LENGTH_LONG).show();
                            }

                            @Override
                            public void onSuccess(JSONObject json) {

                                Log.i("Login Request Success:", json.toString());

                                try {

                                    sharedprefs.createLoginSession(json);
                                    HashMap<String, String> user = sharedprefs.getUserDetails();
                                    String profile_uid = user.get(sharedprefs.KEY_UID);
                                    Intent i = new Intent(getApplicationContext(), TabHostFragmentActivity.class);
                                    i.putExtra("profile_uid", profile_uid);
                                    startActivity(i);
                                    finish();


                                } catch (JSONException e) {
                                    // TODO Auto-generated catch block
                                    e.printStackTrace();
                                }

                            }
                        });










                    }
                }
                if (response.getError() != null) {
                    // Handle errors, will do so later.
                }
            }
        });
        request.executeAsync();
    } 
}

Answer 1

You must always refer to the unique Session class. Every activity has to take an already opened session from the Session class or, if no valid sessions are found, created a new one.

As the official site said you have to manage the session lifecycle in every activity that want to make request to Facebook.
The UiLifecycleHelper is a very useful class that can help you manage the session state among the activities lifecycle (for example the onPause() method of this class deal with the removal of the callback added in the activity in which it's called)

The Session class is defined in order to give a better control on the authentication of the user among the activities and guarantees automatic management of the token cache. Here you can find more details.