Android Firebase Facebook登录会在重新打开应用时显示“退出”按钮

Question

public class MainActivity extends AppCompatActivity {

    private LoginButton facebookloginButton;
    private CallbackManager callbackManager;
    private FirebaseAuth mAuth;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mAuth = FirebaseAuth.getInstance();

        facebookloginButton=(LoginButton)findViewById(R.id.facebook_login_button);
        callbackManager=CallbackManager.Factory.create();
        facebookloginButton.setReadPermissions("email", "public_profile");
        facebookloginButton.registerCallback(callbackManager, new FacebookCallback<LoginResult>() {
            @Override
            public void onSuccess(LoginResult loginResult) {
                handleFacebookAccessToken(loginResult.getAccessToken());
            }

            @Override
            public void onCancel() {

            }

            @Override
            public void onError(FacebookException error) {
                Toast.makeText(getApplicationContext(), "Error",Toast.LENGTH_LONG).show();
            }
        });

    }

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

    private void handleFacebookAccessToken(AccessToken token) {


        AuthCredential credential = FacebookAuthProvider.getCredential(token.getToken());
        mAuth.signInWithCredential(credential)
                .addOnCompleteListener(this, new OnCompleteListener<AuthResult>() {
                    @Override
                    public void onComplete(@NonNull Task<AuthResult> task) {
                        if (task.isSuccessful()) {
                            // Sign in success, update UI with the signed-in user's information

                            FirebaseUser user = mAuth.getCurrentUser();
                            Intent intent=new Intent(getApplicationContext(),NextActivity.class);
                            //  intent.putExtra("NAME",user.getDisplayName());
                            startActivity(intent);
                            finish();

                        } else {
                            // If sign in fails, display a message to the user.

                            Toast.makeText(getApplicationContext(), "Authentication failed.",
                                    Toast.LENGTH_SHORT).show();

                        }

                        // ...
                    }
                });
    }

    @Override
    public void onStart() {
        super.onStart();
        // Check if user is signed in (non-null) and update UI accordingly.
        FirebaseUser currentUser = mAuth.getCurrentUser();
//        currentUser.getDisplayName();
    }

}

I am using Firebase's Facebook Login. I am able to login and if the login is success I am redirecting to NextActivity.

But when I pressed the facebook login button, it shows me the logout button for few seconds and then redirects me to NextActivity. When I close my app and open it again, it shows me the MainActivity with Logout button.

I wanted it to display NextActivity if app is closed and reopened again

Answer 1

You can save the AUTH Token after the successful login from Facebook in you application's Shared Preferences settings and then whenever you start your app you can check if there is any token saved in your storage if it means users have already logged in and redirect directly him to next page or profile page.

Here is small snippet what you can do:

final static String PREFS_NAME = "AUTH" 

public class MainActivity extends AppCompatActivity{

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        settings = getSharedPreferences(PREFS_NAME, MODE_PRIVATE);
        setContentView(R.layout.activity_main);

        // check if user is already logged in
        // i.e. auth token is present or not
        String token = settings.getString("auth_token", null);
        // means user is logged in token was found
        if (token != null) {
            AUTH_TOKEN = token;
            startActivity(new Intent(MainActivity.this, ProfileActivity.class));
        }
    }

        // YOUR REST OF THE CODE ....

});

 @Override
public void onComplete(@NonNull Task<AuthResult> task) {
    if (task.isSuccessful()) {
        // Sign in success, update UI with the signed-in user's information

        FirebaseUser user = mAuth.getCurrentUser();

        // SAVE THE USER DETAILS OR PART OF IT IN SHARED PREFS
        SharedPreferences.Editor editor = settings.edit();
        editor.putString("USER", user);
        editor.apply();

        Intent intent=new Intent(getApplicationContext(),NextActivity.class);
        //  intent.putExtra("NAME",user.getDisplayName());
        startActivity(intent);
        finish();

    } else {
        // If sign in fails, display a message to the user.

        Toast.makeText(getApplicationContext(), "Authentication failed.",
                Toast.LENGTH_SHORT).show();

    }

    // ...
}

this will work since every time you launch your app in onCreate method checks for that AUTH file if it's present it will directly send the user to nextActivity .

Answer 2

You can use Shared Preferences for that purpose.

So in the onCreate of your LoginActivity do this:

    SharedPreferences     settings=getSharedPreferences("prefs",0);
boolean firstRun=settings.getBoolean("firstRun",false);
if(firstRun==false)//if running for first time

{
    //Set the firstRun value to true
    editor.putBoolean("firstRun",true);
    editor.commit();
   //Continue your login process

}
else
{
    // launch NextActivity if app is opened not for the first time
    Intent i=new Intent(check.this, NextActivity.class);
    startActivity(I);
    finish();
}