Facebook Login Implementation

activity_login.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <Button
        android:id="@+id/connect_with_facebook_btn"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Connect with Facebook"
        android:onClick="openFacebookLoginFragment" />

</LinearLayout>

AndroidManifest.xml

<application
 android:icon=”@drawable/ic_launcher”
 android:label=”@string/app_name”>
   ...

   <!—- Facebook login -->
   <activity android:name=”com.facebook.LoginActivity” />

   <meta-data
    android:name=”com.facebook.sdk.ApplicationId”
    android:value=”@string/facebook_app_id” />
</application>

FacebookLoginFragment.java

import android.os.Bundle;
import android.support.annotation.Nullable;
import android.support.v4.app.Fragment;
import android.util.Log;

import com.facebook.Request;
import com.facebook.Response;
import com.facebook.Session;
import com.facebook.SessionState;
import com.facebook.model.GraphUser;

public class FacebookLoginFragment extends Fragment implements Session.StatusCallback {

    private static final String TAG = "FacebookLoginFragment";
    private FacebookAuthListener listener;

    @Override
    public void onActivityCreated(@Nullable Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);

        try {
            listener = (FacebookAuthListener) getActivity();
        } catch (ClassCastException e) {
            throw new RuntimeException("The activity that contains FacebookLoginFragment must implement FacebookLoginFragment.FacebookAuthListener");
        }
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        Session.openActiveSession(getActivity(), true, this);
    }

    @Override
    public void call(Session session, SessionState sessionState, Exception e) {

        Log.d(TAG, "Session opened ? " + session.isOpened());

        if (session.isOpened() && listener.onFacebookAuthentication(session)) {
            getUserData(session);
        }
    }

    private void getUserData(final Session session) {

        Request.newMeRequest(session, new Request.GraphUserCallback() {
            @Override
            public void onCompleted(GraphUser graphUser, Response response) {
                Log.d(TAG, "User info is fetched from Facebook.");
                listener.onFacebookUserFetched(session, graphUser);
            }
        }).executeAsync();
    }

    public interface FacebookAuthListener {

        /**
         * Called when Facebook Authentication is successful. Returns a boolean whether fetching
         * user data is required or not. If true, Facebook user data will be sent
         * via 'onFacebookUserFetched()' method.
         *
         * @param session Facebook session
         * @return
         */
        public boolean onFacebookAuthentication(Session session);

        /**
         * Called when user data is fetched.
         *
         * @param session   Facebook session
         * @param graphUser Facebook user object
         */
        public void onFacebookUserFetched(Session session, GraphUser graphUser);
    }

}

LoginActivity.java

import android.content.Intent;
import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;
import android.util.Log;
import android.view.View;

import com.facebook.Session;
import com.facebook.model.GraphUser;
import com.miwi.R;
import com.miwi.fragment.FacebookLoginFragment;

public class LoginActivity extends ActionBarActivity implements FacebookLoginFragment.FacebookAuthListener {

    private static final String TAG = "LoginActivity";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_login);
    }

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

    /**
     * Opens FacebookLoginFragment. This method is bound from activity_login.xml.
     *
     * @param view
     */
    public void openFacebookLoginFragment(View view) {
        getSupportFragmentManager()
                .beginTransaction()
                .add(android.R.id.content, new FacebookLoginFragment())
                .addToBackStack("FacebookLoginFragment")
                .commit();
    }

    @Override
    public boolean onFacebookAuthentication(Session session) {
        // returning true for fetching user info
        return true;
    }

    @Override
    public void onFacebookUserFetched(Session session, GraphUser graphUser) {

        Log.d(TAG, "App ID: " + session.getApplicationId());
        Log.d(TAG, "Token: " + session.getAccessToken());
        Log.d(TAG, "User: " + graphUser.getName());
    }
}