问每次用户登录时，Google登录都使用相同的帐户

EN

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.login);
    initialize();
    Firebase.setAndroidContext(this);
    ref=new Firebase("https://texter10c.firebaseio.com");

    loginButton.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            progressDialog.setMessage("Logging in !");
            progressDialog.setTitle("Hang on!");
            progressDialog.show();

            ref.authWithPassword(emailField.getText().toString(), passwordField.getText().toString(), new Firebase.AuthResultHandler() {
                @Override
                public void onAuthenticated(AuthData authData) {
                    Log.e("Authenticated","Authenticated");
                    getUserIdandLogin();
                }

                @Override
                public void onAuthenticationError(FirebaseError firebaseError) {
                    progressDialog.dismiss();
                    Toast.makeText(LoginActivity.this, firebaseError.getMessage(), Toast.LENGTH_SHORT).show();
                }
            });
        }
    });

    signupButton.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            Intent intent = new Intent(LoginActivity.this, SignupActivity.class);
            startActivity(intent);
        }
    });

    googleSignInButton.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            progressDialog.setTitle("Contacting Google");
            progressDialog.setMessage("Logging you in");
            progressDialog.show();
            if(!mGoogleApiClient.isConnected())
            mGoogleApiClient.connect();
        }
    });

}

private void getGoogleToken(){

    AsyncTask<Void,Void,String> task=new AsyncTask<Void, Void, String>() {
        @Override
        protected String doInBackground(Void... params) {
            final String scopes="oauth2:"+"https://www.googleapis.com/auth/plus.login"+" "+"https://www.googleapis.com/auth/plus.me";
            try {
                if(!mGoogleApiClient.isConnected())
                {
                    mGoogleApiClient.connect();
                }
                googleAccessToken= GoogleAuthUtil.getToken(LoginActivity.this,Plus.AccountApi.getAccountName(mGoogleApiClient),scopes);
                Log.e("AccessToken",googleAccessToken+"");
            }
            catch (IOException e)
            {
                e.printStackTrace();
            }
            catch (GoogleAuthException e)
            {
                e.printStackTrace();
            }
            return null;
        }

        @Override
        protected void onPostExecute(String s) {
            super.onPostExecute(s);
            try {
                ref.authWithOAuthToken("google", googleAccessToken, new Firebase.AuthResultHandler() {
                    @Override
                    public void onAuthenticated(final AuthData authData) {
                        try {
                            Log.e("Firebase", "Google Authentication Success");
                            Log.e("Username", authData.getProviderData().get("displayName").toString());
                            Log.e("Id", authData.getProviderData().get("id").toString());


                            Firebase googleUserRef = ref.child("UserDetails/names/" + authData.getProviderData().get("id").toString());
                            Map<String, String> googleUserMap = new HashMap<String, String>();
                            googleUserMap.put("Username", authData.getProviderData().get("displayName").toString());
                            final String UserID = "GoogleUser" + authData.getProviderData().get("displayName") + authData.getProviderData().get("id");
                            googleUserMap.put("UserId", UserID);

                            googleUserRef.setValue(googleUserMap, new Firebase.CompletionListener() {
                                @Override
                                public void onComplete(FirebaseError firebaseError, Firebase firebase) {
                                    progressDialog.dismiss();
                                    dataStore.setCurrentUserName(authData.getProviderData().get("displayName").toString());
                                    dataStore.setCurrentUserID(UserID);
                                    storeDatainSharedPreferences();
                                    Intent intent = new Intent(LoginActivity.this, DialogActivity.class);
                                    startActivity(intent);
                                }
                            });
                        }
                        catch (NullPointerException e)
                        {
                            e.printStackTrace();
                        }
                    }

                    @Override
                    public void onAuthenticationError(FirebaseError firebaseError) {
                        Log.e("GogoleAuthFailed", firebaseError.getMessage());

                    }
                });
            }
            catch (NullPointerException e)
            {
                Log.e("Accesstoken problem",e.getMessage());
            }
        }
    };
    task.execute();
}

public void getUserIdandLogin()
{
    dataStore.userDialogMap=new ArrayList<Map<String,String>>();
    dataStore.generatedChatIds=new ArrayList<>();
    Firebase refUser=ref.child("UserDetails/names");
    refUser.addChildEventListener(new ChildEventListener() {
        @Override
        public void onChildAdded(DataSnapshot dataSnapshot, String s) {
            Map<String, String> map = new HashMap<String, String>();
            map = dataSnapshot.getValue(Map.class);
            try{
                if (map.get("Email").equals(emailField.getText().toString()))
                {
                    Toast.makeText(LoginActivity.this, "Successfilly Logged in", Toast.LENGTH_SHORT).show();
                    dataStore.setCurrentUserName(map.get("Username"));
                    dataStore.setCurrentUserID(map.get("UserId"));
                    intent=new Intent(LoginActivity.this,DialogActivity.class);
                    startActivity(intent);
                    storeDatainSharedPreferences();
                    progressDialog.dismiss();
                }

            }
            catch (NullPointerException e)
            {
                Log.e("NullPointerGUser",e.getMessage());
            }
        }

        @Override
        public void onChildChanged(DataSnapshot dataSnapshot, String s) {

        }

        @Override
        public void onChildRemoved(DataSnapshot dataSnapshot) {

        }

        @Override
        public void onChildMoved(DataSnapshot dataSnapshot, String s) {

        }

        @Override
        public void onCancelled(FirebaseError firebaseError) {

        }
    });
}

private void storeDatainSharedPreferences() {
    try {
        SharedPreferences.Editor editor = getSharedPreferences(NEW_PREFS, MODE_PRIVATE).edit();
        editor.putString("CurrentUsername", dataStore.getCurrentUserName());
        editor.putString("CurrentUserId", dataStore.getCurrentUserID());
        editor.commit();
    }
    catch (NoSuchElementException e)
    {
        new AlertDialog.Builder(LoginActivity.this).setMessage("There was an error whil logging in")
                .setTitle("Little Problem here!").setPositiveButton("Retry", new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialog, int which) {
                Intent intent=new Intent(LoginActivity.this,LoginActivity.class);
                removeDatainSharedPreferences();
                mGoogleApiClient.disconnect();
                startActivity(intent);
            }
        }).show();
    }
}

private void removeDatainSharedPreferences() {
    SharedPreferences.Editor editor = getSharedPreferences(NEW_PREFS, MODE_PRIVATE).edit();
    editor.remove("CurrentUsername");
    editor.remove("CurrentUserId");
    editor.commit();
}


private void initialize() {
    emailInputLayout=(TextInputLayout)findViewById(R.id.emailInputLayout);
    emailField=(EditText)findViewById(R.id.emailField);
    passwordField=(EditText)findViewById(R.id.passwordField);
    passwordInputLayout=(TextInputLayout)findViewById(R.id.passwordInputLayout);
    loginButton=(Button)findViewById(R.id.loginButton);
    emailInputLayout.setHint("Email");
    passwordInputLayout.setHint("Password");
    progressDialog=new ProgressDialog(LoginActivity.this);
    signupButton=(TextView)findViewById(R.id.signupButton);
    forgotPasswordButton=(TextView)findViewById(R.id.forgotPasswordField);
    googleSignInButton=(SignInButton)findViewById(R.id.googleSignInButton);
    googleSignInButton.setColorScheme(SignInButton.COLOR_AUTO);
    forgotPasswordButton.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            Intent intent=new Intent(LoginActivity.this,ForgotPasswordActivity.class);
            startActivity(intent);
        }
    });

    SharedPreferences sharePreferences=getSharedPreferences(NEW_PREFS,MODE_PRIVATE);
    if(!sharePreferences.getString("CurrentUsername","null").equals("null")) {
        Log.e("SharedPreferences", sharePreferences.getString("CurrentUsername", "null"));
        Log.e("SharedPreferences",sharePreferences.getString("CurrentUserId",null));
        Intent intent=new Intent(LoginActivity.this,DialogActivity.class);
        startActivity(intent);
    }

    mGoogleApiClient=new GoogleApiClient.Builder(this)
            .addApi(Plus.API)
            .addScope(Plus.SCOPE_PLUS_LOGIN)
            .addScope(Plus.SCOPE_PLUS_PROFILE)
            .addConnectionCallbacks(this)
            .addOnConnectionFailedListener(this).build();


   if(!isNetworkAvailable())
   {
      snackbar=Snackbar.make(findViewById(android.R.id.content),"You are offline",Snackbar.LENGTH_INDEFINITE)
              .setAction("Retry", new View.OnClickListener() {
                  @Override
                  public void onClick(View v) {
                      if(!isNetworkAvailable())
                          dismissSnackBar();
                      else
                          snackbar.show();
                  }

              });
       snackbar.show();
   }

}

private void dismissSnackBar() {
    snackbar.dismiss();
}


private boolean isNetworkAvailable()
{
    ConnectivityManager manager=(ConnectivityManager)getSystemService(Context.CONNECTIVITY_SERVICE);
    NetworkInfo networkIngo=manager.getActiveNetworkInfo();
    return networkIngo!=null&& networkIngo.isConnected();
}

@Override
public void onConnected(@Nullable Bundle bundle) {
        Log.e("GoogleApi","Connected");
        getGoogleToken();
}

@Override
public void onConnectionSuspended(int i) {

}

@Override
public void onConnectionFailed(@NonNull ConnectionResult connectionResult) {
    Log.e("GoogleApi",connectionResult.toString());
    if(!connectionResult.hasResolution())
    {
        GooglePlayServicesUtil.getErrorDialog(connectionResult.getErrorCode(),LoginActivity.this,0).show();
    }
    if(connectionResult.isSuccess())
    {
        getGoogleToken();
    }
    try
    {
        connectionResult.startResolutionForResult(this,100);
    }
    catch (IntentSender.SendIntentException e)
    {
        e.printStackTrace();
    }
}