Facebook Login for Android

The simplest way to add Facebook Login to your app is to add LoginButton from the SDK. This is a custom view implementation of a Button. You can use this button in your app to implement Facebook Login.

In conjunction with the LoginButton, you use the following classes, available in the SDK:

• LoginManager – Initiates the login process with the requested read or publish permissions.
• CallbackManager – Use to route calls back to the Facebook SDK and your registered callbacks. You should call it from the initiating activity or fragments onActivityResult call.
• AccessToken: – Use this class Graph API requests. It shows the user id, and the accepted and denied permissions.
• Profile – This class has basic information about person logged in.

The LoginButton is a UI element that wraps functionality available in the LoginManager. So when someone clicks on the button, the login is initiated with the permissions set in the LoginManager. The button follows the login state, and displays the correct text based on someone’s authentication state.

To add the Facebook Login button, first add it to your layout XML file with the full class name,com.facebook.widget.LoginButton:

Then set up the button in your UI by adding it to a fragment and update your activity to use your fragment.

You can customize the properties of Login button and register a callback in your onCreateView()method.

Properties you can customize includes LoginBehavior, DefaultAudience, ToolTipPopup.Style and permissions on the LoginButton. For example:

If you use the LoginButton in a fragment, you need to set the fragment on the button as shown by callingsetFragment.

You then need to call FacebookSdk.sdkInitialize to initialize the SDK, and then callCallbackManager.Factory.create to create a callback manager to handle login responses. Here’s an example of adding the callback in a fragment:

Finally you should call callbackManager.onActivityResult to pass the login results to theLoginManager via callbackManager.

3. Register a Callback

To respond to a login result, you need to register a callback with either LoginManager or LoginButton. If you register the callback with LoginButton, don’t need to register the callback on Login manager.

You add the callback to your activity or fragment’s onCreate() method:

If login succeeds, the LoginResult parameter has the new AccessToken, and the most recently granted or declined permissions.

You don’t need a registerCallback for login to succeed, you can choose to follow current access token changes with the AccessTokenTracker class described below.

Then in onActivityResult() forward the login results to the callbackManager created inonCreate():

Every activity and fragment that you integrate with the FacebookSDK Login or Share should forwardonActivityResult to the callbackManager

4. Enable Chrome Custom Tabs

Enable Chrome Custom Tabs by adding an intent filter to your manifest and afb_login_protocol_scheme to your strings.xml file. When you enable Chrome Custom Tabs, the SDK presents the login dialog in a Chrome Custom Tab instead of a WebView when the Facebook app is not installed. As a result, people do not have to enter their credentials again if they are already logged into Facebook in their Chrome browser.

Add the following intent filter to your AndroidManifest.xml file:

Add the following in your strings.xml file: