如何将Facebook SDK集成到本机Android应用中

Question

Facebook has a very good documentation of integrating SDKs for Android, iOS & JavaScript etc. But still I have seen some confusions or misunderstandings regarding the exact ways to integrate Facebook SDK.

So I am writing all to the point steps to integrate Facebook SDK in Android Native apps and make use of Graph APIs etc.

In documentation, they have explained it in the way of documentation.

Here I am trying to explain the steps the way we need them while integrating in our app.

I will be giving answers to the most doubts we get, most occurring errors etc.

I hope it will help someone someday.

Answer 1

Facebook provides a wide range of options that can be done by integrating its SDK. But we need to follow some proper steps for the same.

• Login

The very first thing we need to do is Login , before our app starts making use of Facebook SDK we need to do authentication . The user must login with his/her account before our app starts getting benefit from

This can be done in two ways,

a) Via Native Android App

If the user is having Facebook app installed in their phones then they will be asked to login via the account they have logged in with in their facebook app.

b) Via Web View

If user is not having facebook app, then facebook login page is opened in a web browser and user can login to their account.

So by any of these two options, once the user logs in then your app gets authenticated to use their account in your app.

How to do this

Once you include Facebook SDK & Library project in your own Android app then you can simply put their built in widget in any of Your xml file and you will see the Login button there. It's code is simple,

<com.facebook.widget.LoginButton
        android:id="@+id/authButton"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center_horizontal"
        android:layout_marginTop="30dp"
        />

Just include the above mentioned code in your XML file (where ever you want to show Facebook Login button.) It will automatically create the Login button like the following,

Confusions/Doubts/Questions we have in our minds up till this stage

Q. How can I create the button like this in my own app? From where am I going to get logo or what color does it have etc. etc.

Ans. We don't need to create it on our own, we just put that widget in our code and the button is created automatically.

• Authorization

Okay, fine we have included the Facebook login button, now user can do login into our app, next what?

Next Facebook provides many kind of options we can do, like Share something on their profile, Post a status or custom story, get user's liked pages, access their messages, posts, feeds, friend list blah blah blah.

But it is not like that user logged in with their account and we can do anything we want in our app with their facebook account.

The next term which comes in to action is Permissions

To perform a specific task we need related permission, if the user will give you permission to do so with their Facebook account, only then our app will be able to do.

For example, to access user's likes we need user_likes permission, to post something on behalf of user on their profile we need publish_actions permission etc. Complete list of permissions can be found here

So after authentication, the next thing is authorization . What our app is authorized to do with user's account.

How to get permissions

As we have already created a Login button for facebook using their button widget, now we can provide the permissions as a list to that button, so it will let the user know about what permissions you want from them when they login with their account.

Clearing the doubt here

YES, the user will be told what permissions your app wants from them while doing login. Simply you can say, the user will be told what your app can do with their facebook account like accessing their friend list, post something on their profile, reading contacts etc. However the user may or may not read it, but the login button let them know about everything.

How to add permissions to Facebook login button

LoginButton authButton = (LoginButton) view.findViewById(R.id.authButton);
authButton.setFragment(this);
authButton.setReadPermissions(Arrays.asList("user_likes", "user_status", "publish_actions"));

So you can see we are providing a list of permissions we want. However it is even possible to ask for more permissions later on, so it is more advisable to firstly ask for basic permissions and ask for permissions like publish_actions, when user would want it.

• Session

Session is a very common term mostly in case of web applications. It serves the similar purpose here. Once the user logs in with their facebook account, a Session is created in your app with the facebook and it remains until the user logs out.

Q. How to show Facebook log out button?

Ans. You will be very happy to hear this, you don't need to do anything to show log out button, once the user logs in, the login button is automatically changed to logout button.

Benefit of Session

Session object has the authentication token that enables us to perform any action with Facebook SDK.

We can get the facebook session object at any time by calling the following method,

Session session = Session.getActiveSession();

• UiLifecycleHelper class

Although we have done all the steps, but we need to maintain the session properly then we are going to need this class. We just need to put it in all our activity life cycle methods so that the facebook session is maintained accordingly.

Define an instance variable in your activity,

private UiLifecycleHelper uiHelper;

Then add the following code,

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    uiHelper = new UiLifecycleHelper(getActivity(), callback);
    uiHelper.onCreate(savedInstanceState);
}

@Override
public void onResume() {
    super.onResume();
    uiHelper.onResume();
}

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

@Override
public void onPause() {
    super.onPause();
    uiHelper.onPause();
}

@Override
public void onDestroy() {
    super.onDestroy();
    uiHelper.onDestroy();
}

@Override
public void onSaveInstanceState(Bundle outState) {
    super.onSaveInstanceState(outState);
    uiHelper.onSaveInstanceState(outState);
}

Now the facebook session will be maintained automatically without your headache.

• Calling the Graph API

I am going to give you a very simple and basic example here, suppose we want to get the list of the pages the user has liked, then we can do it with the following code,

Session session = Session.getActiveSession();
new Request(
    session,
    "/me/likes",
    null,
    HttpMethod.GET,
    new Request.Callback() {
        public void onCompleted(Response response) {

                 //Do what you want to with the response

        }
    }
).executeAsync();

Q. How it is going to fetch data related to the current user? We have not mentioned any user id any where?

Ans. The answer to this question is that we are using me object here, which will automatically point to the current user who has logged in to using facebook account.