Facebook使用Firebase BaaS登录Android

我正在关注this Firebase教程，将Facebook整合到我的应用中 . 一切都很好看，除了我有这个例外的事实：

com.google.firebase.auth.FirebaseAuthUserCollisionException：已存在具有相同电子邮件地址但登录凭据不同的帐户 . 使用与此电子邮件地址关联的提供商登录 .

公平对待，考虑到这正是我正在努力做的事情 . 首先，我创建了一个代码，将gmail集成到我的应用程序，并使用我的电子邮件帐户登录 . 然后我尝试使用Facebook登录，并得到了错误 .

正在搜索如何解决这个问题，我找到了here

如果已存在具有凭证声明的电子邮件地址的帐户，则抛出FirebaseAuthUserCollisionException . 通过调用fetchProvidersForEmail（String）解决此问题，然后要求用户使用其中一个登录 .

最后问题是我正确使用 fetchProvidersForEmail 方法，因为我的任务没有成功（检查最后一段代码） .

任何人都可以给予支持吗？谢谢，

*以下代码目前支持登录gmail和Facebook . 我在这里讲的方法是最后一个， handleFacebookAccessToken .

public class SignInActivity extends AppCompatActivity implements GoogleApiClient.OnConnectionFailedListener, View.OnClickListener {

/**
 * References
 * https://developers.google.com/identity/sign-in/android/sign-in#configure_google_sign-in_and_the_googleapiclient_object
 */

// Here a simple Sign-In button is used to initiate authentication. In this step you will
// implement the logic to Sign-In with Google then use that Google account to authenticate with
// Firebase.

private static final String TAG = "SignInActivity";
private static final int RC_SIGN_IN = 9001;
private GoogleApiClient mGoogleApiClient;
private FirebaseAuth mAuth;

private FirebaseAuth.AuthStateListener mAuthListener;

LoginButton facebookLogin;
CallbackManager cM;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    FacebookSdk.sdkInitialize(this.getApplicationContext());
    setContentView(R.layout.activity_sign_in);

    cM = CallbackManager.Factory.create();
    facebookLogin = (LoginButton) findViewById(R.id.sign_in_button_facebook);
    if (facebookLogin != null) {
        facebookLogin.setReadPermissions("public_profile", "email", "user_friends");
        facebookLogin.registerCallback(cM, new FacebookCallback<LoginResult>() {
            @Override
            public void onSuccess(LoginResult loginResult) {
                Log.d(TAG, "facebook:onSuccess:" + loginResult);
                handleFacebookAccessToken(loginResult.getAccessToken());
            }

            @Override
            public void onCancel() {
                Log.d(TAG, "facebook:onCancel");
                // ...
            }

            @Override
            public void onError(FacebookException error) {
                Log.d(TAG, "facebook:onError", error);
                // ...
            }
        });
    }

    // Configure Google Sign-In to request the user data required by the app. For example, to
    // configure Google Sign-In to request users' ID and basic profile information, create a
    // GoogleSignInOptions object with the DEFAULT_SIGN_IN parameter (ID and basic profile are
    // included in DEFAULT_SIGN_IN). To request users' email addresses as well, create the
    // GoogleSignInOptions object with the requestEmail option.
    GoogleSignInOptions mGoogleSignInOptions = new GoogleSignInOptions
            .Builder(GoogleSignInOptions.DEFAULT_SIGN_IN)
            .requestIdToken(getString(R.string.default_web_client_id))
            .requestEmail()
            .build();

    // Create a GoogleApiClient object with access to the Google Sign-In API and the options
    // specified. Note: To use enableAutoManage, your activity must extend FragmentActivity or
    // AppCompatActivity (a subclass of FragmentActivity), both of which are part of the Android
    // Support Library. You can use GoogleApiClient in a Fragment; however, the fragment's
    // parent activity must be a FragmentActivity. If you can't extend FragmentActivity, you
    // must manually manage the GoogleApiClient connection lifecycle.
    mGoogleApiClient = new GoogleApiClient
            .Builder(this)
            .enableAutoManage(this /* FragmentActivity */, this /* OnConnectionFailedListener */)
            .addApi(Auth.GOOGLE_SIGN_IN_API, mGoogleSignInOptions)
            .build();

    // Configure the sign in button.
    SignInButton mSignInButton = (SignInButton) findViewById(R.id.sign_in_button);
    if (mSignInButton != null) {
        mSignInButton.setSize(SignInButton.SIZE_STANDARD);
        mSignInButton.setOnClickListener(this);
    }

    // Initialize FirebaseAuth
    mAuth = FirebaseAuth.getInstance();

    mAuthListener = new FirebaseAuth.AuthStateListener() {
        @Override
        public void onAuthStateChanged(@NonNull FirebaseAuth firebaseAuth) {
            FirebaseUser user = firebaseAuth.getCurrentUser();
            if (user != null) {
                // User is signed in
                Log.d(TAG, "onAuthStateChanged:signed_in:" + user.getUid());
            } else {
                // User is signed out
                Log.d(TAG, "onAuthStateChanged:signed_out");
            }
            // ...
        }
    };
}

@Override
public void onClick(View v) {
    switch (v.getId()) {
        case R.id.sign_in_button:
            signIn();
            break;
    }
}

@Override
public void onResume() {
    super.onResume();
    mAuth.addAuthStateListener(mAuthListener);
}

@Override
public void onPause() {
    super.onPause();
    if (mAuthListener != null) {
        mAuth.removeAuthStateListener(mAuthListener);
    }
}

// Handle sign-in button taps by creating a sign-in intent with the getSignInIntent method, and
// starting the intent with startActivityForResult. Starting the intent prompts the user to
// select a Google account to sign in with. If you requested scopes beyond profile, email, and
// openid, the user is also prompted to grant access to the requested resources.
private void signIn() {
    Intent signInIntent = Auth.GoogleSignInApi.getSignInIntent(mGoogleApiClient);
    startActivityForResult(signInIntent, RC_SIGN_IN);
}

// An unresolvable error has occurred and Google APIs (including Sign-In) will not be available.
@Override
public void onConnectionFailed(@NonNull ConnectionResult connectionResult) {
    Log.d(TAG, "onConnectionFailed:" + connectionResult);
    Toast.makeText(this, "Google Play Services error.", Toast.LENGTH_SHORT).show();
}

// Handle the result of the Google Sign In in the activity's onActivityResult method, which
// retrieve the sign-in result with getSignInResultFromIntent.
@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data);

    cM.onActivityResult(requestCode, resultCode, data);

    // Result returned from launching the Intent from GoogleSignInApi.getSignInIntent(...);
    if (requestCode == RC_SIGN_IN) {
        GoogleSignInResult result = Auth.GoogleSignInApi.getSignInResultFromIntent(data);
        handleSignInResult(result);
    }
}

// After you retrieve the sign-in result, you can check if sign-in succeeded with the isSuccess
// method. If sign-in succeeded, you can call the getSignInAccount method to get a
// GoogleSignInAccount object that contains information about the signed-in user, such as the
// user's name. You can also get the user's email address with getEmail, the user's Google ID
// (for client-side use) with getId, and an ID token for the user with with getIdToken. If you
// need to pass the currently signed-in user to a backend server, send the ID token to your
// backend server and validate the token on the server.
public void handleSignInResult(GoogleSignInResult result) {
    if (result.isSuccess()) {
        GoogleSignInAccount account = result.getSignInAccount();

        // Google Sign In was successful, authenticate with Firebase.
        firebaseAuthWithGoogle(account);

    } else {
        // Google Sign In failed
        // TODO: 26/06/2016 Handle no internet connection
        Log.e(TAG, "Google Sign In failed.");
    }
}

// Add the required firebaseAuthWithGoogle method to authenticate with the signed in Google
// account.
private void firebaseAuthWithGoogle(GoogleSignInAccount acct) {
    Log.d(TAG, "firebaseAuthWithGooogle:" + acct.getId());

    AuthCredential credential = GoogleAuthProvider.getCredential(acct.getIdToken(), null);
    mAuth
            .signInWithCredential(credential)
            .addOnCompleteListener(this, new OnCompleteListener<AuthResult>() {
                @Override
                public void onComplete(@NonNull Task<AuthResult> task) {
                    Log.d(TAG, "signInWithCredential:onComplete:" + task.isSuccessful());

                    // If sign in fails, display a message to the user. If sign in succeeds
                    // the auth state listener will be notified and logic to handle the
                    // signed in user can be handled in the listener.

                    if (!task.isSuccessful()) {
                        Log.w(TAG, "signInWithCredential", task.getException());
                        Toast.makeText(SignInActivity.this, "Authentication failed.", Toast.LENGTH_SHORT).show();

                    } else {
                        startActivity(new Intent(SignInActivity.this, MainActivity.class));
                        finish();
                    }
                }
            });
}

private void handleFacebookAccessToken(AccessToken token) {
    Log.d(TAG, "handleFacebookAccessToken:" + token);

    // This commented block below is what is on the tutorial, but gives the exceptio explained.
    /*
    AuthCredential credential = FacebookAuthProvider.getCredential(token.getToken());
    mAuth.signInWithCredential(credential).addOnCompleteListener(this, new OnCompleteListener<AuthResult>() {
        @Override
        public void onComplete(@NonNull Task<AuthResult> task) {
            Log.d(TAG, "signInWithCredential:onComplete:" + task.isSuccessful());

            // If sign in fails, display a message to the user. If sign in succeeds
            // the auth state listener will be notified and logic to handle the
            // signed in user can be handled in the listener.
            if (!task.isSuccessful()) {
                Log.w(TAG, "signInWithCredential", task.getException());
                Toast.makeText(SignInActivity.this, "Authentication failed.", Toast.LENGTH_SHORT).show();
            }

            // ...
        }
    });
    */

    mAuth.fetchProvidersForEmail("i_put_here_my_email@gmail.com").addOnCompleteListener(this, new OnCompleteListener<ProviderQueryResult>() {
        @Override
        public void onComplete(@NonNull Task<ProviderQueryResult> task) {
            Log.d(TAG, "signInWithCredential:onComplete:" + task.isSuccessful());

            // If sign in fails, display a message to the user. If sign in succeeds
            // the auth state listener will be notified and logic to handle the
            // signed in user can be handled in the listener.
            if (!task.isSuccessful()) {
                Log.w(TAG, "signInWithCredential", task.getException());
                Toast.makeText(SignInActivity.this, "Authentication failed.", Toast.LENGTH_SHORT).show();
            } else {
                startActivity(new Intent(SignInActivity.this, MainActivity.class));
                finish();
            }
        }
    });
}

}