Facebook AccessToken.getAccessToken is null on opening of app even after first login

问题

I have integrated latest Facebook android sdk (Sdk 4.0). This is the code I have added in my onCreate method.

FacebookSdk.sdkInitialize(this.getApplicationContext());
            callbackManager = CallbackManager.Factory.create();
            if(AccessToken.getCurrentAccessToken()!=null){
                Log.d(FBTAG,"facebook already logged in");
                isFBLogin = true;
            }
            LoginManager.getInstance().registerCallback(callbackManager,
                    new FacebookCallback<LoginResult>() {
                        @Override
                        public void onSuccess(LoginResult loginResult) {
                            // App code
                            Log.d(FBTAG,"facebook log in");
                            isFBLogin = true;
                        }

                        @Override
                        public void onCancel() {
                             // App code
                            isFBLogin = false;
                        }

                        @Override
                        public void onError(FacebookException error) {
                            isFBLogin = false;
                            Log.d(FBTAG,"facebook login error: "+error);
                            // App code

                        }
            });

And this is the code I have used for onClickLogin

public void onClickLogin() {
        LoginManager.getInstance().logInWithPublishPermissions(this, PERMISSIONS);
    }

I am able to login by clicking on the login button and processing onClickLogin function. Now next time I am opening the app the app I am checking for AccessToken.getAccessToken to check if the user is already logged in at facebook but it is always coming as null. Isn't there anyway in the new sdk to login in the background so that I don't have to ask the user to login always like it used to be in the previous version in session class.

回答1:

The access token that was returned by the LoginManager will be saved in shared preferences, so the next time the app is opened, AccessToken.getCurrentAccessToken() should have the same access token, this is the same as how it with the Session class. You can check out the samples provided with the SDK to see them work.

Make sure you're not reinstalling the app between sessions, or setting the current access token to null explicitly.

回答2:

You can also add an InitializeCallback to the sdkInitialize and check the AccessToken inside the callback:

FacebookSdk.sdkInitialize(getApplicationContext(), new FacebookSdk.InitializeCallback() {
        @Override
        public void onInitialized() {
            if(AccessToken.getCurrentAccessToken() == null){
                System.out.println("not logged in yet");
            } else {
                System.out.println("Logged in");
            }
        }
    });

回答3:

I have not tested this myself but what I think you can do is to get the AccessToken from the LoginResult object in the onSuccess method of the callback.

So: AccessToken accessToken = loginResult.getAccessToken();

Then you would save this accessToken down by saying:

AccessToken.setAccessToken(accessToken);

Then when you call AccessToken.getAccessToken, it should return the accessToken you have saved.

回答4:

Android Facebook sdk Initialization is take some time Initialize. so you need to wait just 100 milliseconds before calling AccessToken.getCurrentAccessToken()

once try this solution it is working for me ::

        FacebookSdk.sdkInitialize(this.getApplicationContext());
    callbackManager = CallbackManager.Factory.create();

    new Handler().postDelayed(new Runnable() {
        @Override
        public void run() {


            if (AccessToken.getCurrentAccessToken() != null) {
                Log.d(FBTAG, "facebook already logged in");
                isFBLogin = true;
            }
            LoginManager.getInstance().registerCallback(callbackManager,
                    new FacebookCallback<LoginResult>() {
                        @Override
                        public void onSuccess(LoginResult loginResult) {
                            // App code
                            Log.d(FBTAG, "facebook log in");
                            isFBLogin = true;
                        }

                        @Override
                        public void onCancel() {
                            // App code
                            isFBLogin = false;
                        }

                        @Override
                        public void onError(FacebookException error) {
                            isFBLogin = false;
                            Log.d(FBTAG, "facebook login error: " + error);
                            // App code

                        }
                    });


        }
    }, 100);

回答5:

Please add the following code:

protected void onActivityResult(int requestCode, int resultCode, Intent data)
{
    //super.onActivityResult(requestCode, resultCode, data);
    callbackManager.onActivityResult(requestCode,resultCode,data);
}

回答6:

Reason is Facebook SDK profile caching.

    AccessToken.setCurrentAccessToken(null); 
    Profile.setCurrentProfile(null);

Before destroying activity try it. Maybe it can solve your problem. First time working it is clean cache second time you can login different account.

回答7:

1.Change your function to this function

public void onClickLogin() {
    LoginManager.getInstance().logInWithReadPermissions(activity_name.this, PERMISSIONS);
}

回答8:

Steps

1) FacebookSdk.sdkInitialize(getActivity().getApplicationContext());

2) CallbackManager mCallbackManager = CallbackManager.Factory.create();

    LoginManager.getInstance().registerCallback(mCallbackManager,
            new FacebookCallback<LoginResult>() {

                @Override
                public void onSuccess(LoginResult loginResult) {
                    //you will get access token here
                    mAccessToken = loginResult.getAccessToken();



                }

                @Override
                public void onCancel() {

                }

                @Override
                public void onError(FacebookException error) {

                }
            });

3) //get access token afterward by using AccessToken mAccessToken=AccessToken.getCurrentAccessToken();

Make Sure , If you use facebook login from fragment,

1)make sure you call super.onActivityResult() in fragment with Facebook callback manager.

2)check the super.onActivityResult() gets called in related "fragment activity" if you override onActivityResult in related activity.

来源：https://stackoverflow.com/questions/29366945/facebook-accesstoken-getaccesstoken-is-null-on-opening-of-app-even-after-first-l