首次登录后，Facebook Profile.getCurrentProfile()始终返回null [英] Facebook Profile.getCurrentProfile() is always returns null after the first login

问题描述

我第一次通过Facebook登录该应用程序时，是从Profile.getCurrentProfile();

For the first time when I login into the app through Facebook, I'm getting profile from Profile.getCurrentProfile();

就像我退出应用程序并再次启动时一样，它已经登录.因此我可以直接调用Profile.getCurrentProfile();返回null.

Where as when I exit the app and launch again, It was already logged in. So I can call directly Profile.getCurrentProfile(); is returning null.

代码

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    FacebookSdk.sdkInitialize(getApplicationContext());
    setContentView(R.layout.activity_page);
    Profile profile = Profile.getCurrentProfile();
    // For the first launch the profile will be null
    displayProfileName(profile);
    LoginButton loginButton = (LoginButton) findViewById(R.id.login_button);
    loginButton.setReadPermissions("public_profile");
    callbackManager = CallbackManager.Factory.create();
    loginButton.registerCallback(callbackManager,
            new FacebookCallback<LoginResult>() {
                @Override
                public void onSuccess(final LoginResult loginResult) {
                    profileTracker = new ProfileTracker() {

                        @Override
                        protected void onCurrentProfileChanged(
                                Profile oldProfile, Profile currentProfile) {
                            profileTracker.stopTracking();
                            Profile.setCurrentProfile(currentProfile);
                            Profile profile = Profile.getCurrentProfile();
                            displayProfileName(profile);
                        }
                    };
                    profileTracker.startTracking();
                }

                @Override
                public void onCancel() {
                }

                @Override
                public void onError(FacebookException exception) {
                }
            });
}

@Override
protected void onDestroy() {
    super.onDestroy();
    if (profileTracker != null) {
        profileTracker.stopTracking();
    }
}

@Override
protected void onPause() {
    super.onPause();
    // Logs 'app deactivate' App Event.
    AppEventsLogger.deactivateApp(this);
}

@Override
protected void onRestart() {
    super.onRestart();
    AppEventsLogger.activateApp(this);
}
/**
*
* Method to display the Profile Name 
*/
private void displayProfileName(Profile profile) {
    if (profile != null) {
        Toast.makeText(MainActivity.this, profile.getName(),
                Toast.LENGTH_LONG).show();
    } else {
        Toast.makeText(MainActivity.this, "No Profile", Toast.LENGTH_LONG)
                .show();
    }
}


@Override
protected void onActivityResult(int arg0, int arg1, Intent arg2) {
    super.onActivityResult(arg0, arg1, arg2);
    callbackManager.onActivityResult(arg0, arg1, arg2);
}

推荐答案

有两种情况:

1. 首次登录时，请遵循我的其他答案.
2. 对于第二次登录，您将需要刷新您的AccessToken，然后获取配置文件.可以在此答案中找到刷新的令牌代码，但是下面的代码具有此代码(为简化起见).

1. For first login, follow my other answer.
2. For second login, you will need to refresh your AccessToken and then fetch the profile. Refreshing token code can be found in this answer but the code below has it (for simplification).

该代码取自 FB的可怕文档).

您可以将此代码直接放入您的应用中，其中注释为案例1"，只需调用您的常规FB登录即可.

You can put this code straight into your app, where the comment says "case 1", just invoke your normal FB login.

private AccessTokenTracker mAccessTokenTracker;

private void loginToMyFbApp() {
    FacebookSdk.sdkInitialize(this);
    if (AccessToken.getCurrentAccessToken() != null) {
        mAccessTokenTracker = new AccessTokenTracker() {
            @Override
            protected void onCurrentAccessTokenChanged(AccessToken oldAccessToken, AccessToken currentAccessToken) {
                mAccessTokenTracker.stopTracking();
                if(currentAccessToken == null) {
                    //(the user has revoked your permissions -
                    //by going to his settings and deleted your app)
                    //do the simple login to FaceBook
                    //case 1
                }
                else {
                    //you've got the new access token now.
                    //AccessToken.getToken() could be same for both
                    //parameters but you should only use "currentAccessToken"
                    //case 2
                    fetchProfile();
                }
            }
        };
        mAccessTokenTracker.startTracking();
        AccessToken.refreshCurrentAccessTokenAsync();
    }
    else {
        //do the simple login to FaceBook
        //case 1
    }
}

private void fetchProfile() {
    GraphRequest request = GraphRequest.newMeRequest(
            AccessToken.getCurrentAccessToken(),
            new GraphRequest.GraphJSONObjectCallback() {
                @Override
                public void onCompleted(JSONObject object, GraphResponse response) {
                    // this is where you should have the profile
                    Log.v("fetched info", object.toString());
                }
            });
    Bundle parameters = new Bundle();
    parameters.putString("fields", "id,name,link"); //write the fields you need
    request.setParameters(parameters);
    request.executeAsync();
}

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